U Blox5 Protocol Specifications

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u-blox AG
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Phone +41 44 722 7444
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u-blox 5
NMEA, UBX Protocol Specification
u-blox 5 GNSS Receiver

Specification

Public Release

Title

NMEA, UBX Protocol Specification

Subtitle

u-blox 5 GNSS Receiver

Doc Type

Specification

Doc Id

GPS.G5-X-07036-D

Revision

Date

Author

Status / Comment

29328

12 Aug 2008

EF

Draft

Public Release

This document and the use of any information contained therein, is subject to the acceptance of the u-blox
terms and conditions. They can be downloaded from www.u-blox.com. u-blox makes no warranties based on
the accuracy or completeness of the contents of this document and reserves the right to make changes to
specifications and product descriptions at any time without notice. u-blox reserves all rights to this document
and the information contained herein. Reproduction, use or disclosure to third parties without express
permission is strictly prohibited. Copyright © 2008, u-blox AG.
For most recent documents, please visit www.u-blox.com

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Receiver Description
Serial Communication Ports Description
The u-blox 5 positioning technology comes with a highly flexible communication interface. It supports both the
NMEA and the proprietary UBX protocol. It is truly multi-port and multi-protocol capable. Each protocol (UBX,
NMEA) can be assigned to several ports at the same time (multi-port capability) with individual settings (e.g.
baud rate, messages enabled, etc.) for each port. It is even possible to assign more than one protocol (e.g. UBX
protocol and NMEA at the same time) to a single port (multi-protocol capability), which is particularly useful for
debugging purposes.
The UBX and/or NMEA protocol must be activated to get a message on a port using the UBX proprietary
message UBX-CFG-PRT, which also allows to change port-specific settings (baud rate, address etc.). See
CFG-MSG for a description of the mechanism of enabling and disabling messages.

UART Ports
The receivers feature one or two universal asynchronous receiver/transmitter (UART) ports that can be used to
transmit GPS measurements, monitor status information and configure the receiver. The availability of the
second port depends on the type of module or chip set (see our online product selector matrix for modules and
chip sets).
The serial ports consist of an RX and a TX line. Neither handshaking signals nor hardware flow control signals
are available. These serial ports operate in asynchronous mode. The baud rates can be configured individually
for each serial port. However, there is no support for setting different baud rates for reception and transmission
or for different protocols on the same port.
Possible UART Interface Configurations
Baud Rate

Data Bits

4800
9600
19200
38400
57600
115200

Parity

8
8
8
8
8
8

none
none
none
none
none
none

Stop Bits

1
1
1
1
1
1

If too much data is being configured for a certain port's bandwidth (e.g. all UBX messages shall be
output on a UART port with a baud rate of 9600), the buffer will fill up. Once the buffer's space is
exceeded, the receiver will deactivate messages automatically.
Please note that for protocols such as NMEA or UBX, it does not make sense to change the default values of
word length (data bits) since these properties are defined by the protocol, not by the electrical interface.
See CFG-PRT for UART for a description on the contents of the UART port configuration message.

USB Port
The receivers feature one USB (Universal Serial Bus) port, depending on the type of module or chip set (see our
online product selector matrix for modules and chip sets). This port can be used not only for communication
purposes, but also to power the GPS receiver.
The USB interface supports two different power modes:
NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Receiver Description
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• In the Self Powered Mode the receiver is powered by its own power supply. VDDUSB is used to detect the
availability of the USB port, i.e. whether the the receiver is connected to a USB host.
• In the Bus Powered Mode the device is powered by the USB bus, therefore no additional power supply is
needed. The default maximum current that can be drawn by the receiver is 120mA in that mode. See
CFG-USB for a description on how to change this maximum. Configuring the Bus Powered Mode implies
that the device enters a low power state with disabled GPS functionality when the host suspends the device,
e.g. when the host is put into stand-by mode.
The voltage range for VDDUSB is specified from 3.0V to 3.6V, which differs slightly from the
specification for VCC

DDC Port
A DDC Bus (Display Data Channel) is implemented, which is a 2-wire communication interface compatible with
the I2C standard (Inter-Integrated Circuit). Its availability is depending on the type of module or chip set (see
our online product selector matrix for modules and chip sets).
In contrast to all other interfaces, the DDC is not able to communicate in full-duplex mode, i.e. TX and RX are
mutually exclusive. u-blox 5 acts as a slave in the communication setup, therefore it cannot initiate data
transfers on its own. The master provides the data clock, therefore master and slave don't need to be
configured to use the same baud rate. Moreover, a baud rate setting is not applicable for the slave.
The baud rate clock provided by the master must not exceed 100kHz
The receiver's DDC address is set to 0x42 by default. This address can be changed by setting the mode field in
CFG-PRT for DDC accordingly.
As the receiver will be run in slave mode and the physical layer lacks a handshake mechanism to inform the
master about data availability, a layer has been inserted between the physical layer and the UBX and NMEA
layer. The DDC implements a simple streaming interface that allows the constant polling of data, discarding
everything that is not parseable. This means that the receiver returns 0xFF if no data is available.
If no data is polled for an extended period, the receiver temporarily stops writing data to the output buffer to
prevent overflowing.

Read Access
To allow both polled access to the full message stream and quick access to the key data, the register layout
depicted in Figure DDC Register Layout is provided. The data registers 0 to 252, at addresses 0x00 to 0xFC,
each 1 byte in size, contain information to be defined at a later point in time. At addresses 0xFD and 0xFE, the
currently available number of bytes in the message stream can be read. At address 0xFF, the message stream is
located. Subsequent reads from 0xFF return the messages in the transmit buffer, byte by byte. If the number of
bytes read exceeds the number of bytes indicated, the payload is padded using the value 0xFF.
The registers 0x00 to 0xFC will be defined in a later firmware release. Do not use them, as they
don't provide any meaningful data!

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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DDC Register Layout

Random Read Access
Random read operations allow the master to access any register in a random manner. To perform this type of
read operation, first the register address to read from must be written to the receiver (see Figure DDC Random
Read Access). Following the start condition from the master, the 7-bit device address including the RW bit
(which is a logic low for write access) are clocked onto the bus by the master transmitter. The receiver answers
with an acknowledge (logic low) to indicate that it is responsible for the given address. Next, the 8-bit address
of the register to be read must be written to the bus. Following the receiver’s acknowledge, the master again
triggers a start condition and writes the device address, but this time the RW bit is a logic high to initiate the
read access. Now, the master can read 1 to N bytes from the receiver, generating a not-acknowledge and a
stop condition after the last byte being read. After every byte being read, the internal address counter is
incremented by one, saturating at 0xFF. This saturation means, that, after having read all registers coming after
the initially set register address, the raw message stream can be read.

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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DDC Random Read Access

Current Address Read
The receiver contains an address counter that maintains the address of the last register accessed, internally
incremented by one. Therefore, if the previous read access was to address n (n is any legal address), the next
current address read operation would access data from address n+1 (see Figure DDC Current Address Read
Access). Upon receipt of the device address with the RW bit set to one, the receiver issues an acknowledge and
the master can read 1 to N bytes from the receiver, generating a not-acknowledge and a stop condition after
the last byte being read.
To allow direct access to streaming data, the internal address counter is initialized to 0xFF, meaning that
current address reads without a preceding random read access return the raw message stream. The address
counter can be set to another address at any point in time using a random read access.
DDC Current Address Read Access

Write Access
The receiver does not provide any write access except for writing UBX messages (and NMEA messages) to the
receiver, such as configuration or aiding data. Therefore, the register set mentioned in section Read Access is
not writable. Following the start condition from the master, the 7-bit device address including the RW bit (which
NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Receiver Description
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is a logic low for write access) are clocked onto the bus by the master transmitter. The receiver answers with an
acknowledge (logic low) to indicate that it is responsible for the given address. Now, the master can write 2 to
N bytes to the receiver, generating stop condition after the last byte being written. The number of bytes must
exceed 2 to properly distinguish from the write access to set the address counter in random read accesses.
DDC Write Access

SPI Port
An SPI Bus (Serial Peripheral Interface is provided, depending on the type of module or chip set (see our online
product selector matrix for modules and chip sets). The SPI is a 3-wire synchronous communication interface; In
contrast to UART the master provides a clock, meaning that master and slave don't need to be configured to
use the same baud rate. Moreover, a baud rate setting is not applicable for the slave. SPI modes 0-3 are
implemented and can be configured using the field mode.spiMode in CFG-PRT for SPI (default is SPI mode 0).
The baud rate clock provided by the master must not exceed 250kHz

Read Access
As the register mode is not implemented for the SPI port, only the UBX/NMEA message stream is provided. This
stream is accessed using the Back-To-Back Read and Write Access (see section Back-To-Back Read and Write
Access). When no data is available to be written to the receiver, MOSI should be held logic high, i.e. all bytes
written to the receiver are set to 0xFF.
In order to prevent the receiver from being busy parsing the incoming data, the parsing process is stopped after
20 subsequent bytes containing 0xFF. The parsing process gets re-enabled with the first byte not equal to 0xFF.
The number of bytes to wait for deactivation (20 by default) can be adjusted using the field mode.ffCnt in
CFG-PRT for SPI.
If the receiver has no more data to send, it pulls MISO to logic high, i.e. all bytes transmitted are set to 0xFF.
This means that the master should ignore all 0xFF which are not part of a message. It can resume data
processing as soon as the first byte not equalling 0xFF is received.

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Back-To-Back Read and Write Access
The receiver does not provide any write access except for writing UBX messages (and eventually NMEA
messages) to the receiver, such as configuration or aiding data. For every byte written to the receiver, a byte
must be read from the receiver; the master writes to MOSI and, at the same time, it reads from MISO. The data
on MISO represents the results from a current address read, returning 0xFF when no more data is available.
SPI Back-To-Back Read/Write Access

How to change between protocols
Reconfiguring a port
needs to be enabled
NMEA and UBX). By
necessary to change
messages.

from one protocol to another is a two-step process. First of all, the preferred protocol(s)
to a port using CFG-PRT. One port can handle several protocols at the same time (e.g.
default, all ports are configured for UBX and NMEA protocol so in most cases, it’s not
the port settings at all. Port settings can be viewed and changed using the CFG-PRT

As a second step, activate certain messages on each port using CFG-MSG.
Despite the fact that concatenation of several configurations is still possible on receivers before
u-blox 5, the use of this feature is discouraged as it won't work on u-blox 5. u-blox 5 has 6 I/O
ports, so backwards compatibility is dropped at this point.
This message can be used to initiate receiver restart scenarios, optionally erasing information the receiver has
acquired.
Typically, in GPS receivers, one distinguishes between Cold-, Warm- and Hotstarts, depending on the type of
valid information the receiver has at the time of the restart.
• Coldstart In this startup mode, the receiver has no a-priori information on last position, time, velocity,
frequency etc. Therefore, the receiver has to search the full time- and frequency space, and also all possible
satellite numbers. If a satellite signal is found, it is being tracked to decode ephemeris (18-36 seconds under
strong signal conditions), whereas the other channels continue to search satellites. Once there are sufficient
number of satellites with valid ephemeris, the receiver can calculate position- and velocity data. Please note
that some competitors call this startup mode Factory Startup.
• Warmstart In warmstart mode, the receiver has approximate information of time, position, and coarse data
on Satellite positions (Almanac). In this mode, after power-up, the receiver basically needs to download
ephemeris until it can calculate position- and velocity data. As the ephemeris data usually is outdated after 4
NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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hours, the receiver will typically start with a warmstart if it was powered down for more than that amount of
time. For this scenario, several augmentations exist. See the sections on AssistNOW online and offline.
• Hotstart In Hotstart, the receiver was powered down only for a short time (4 hours or less), so that its
ephemeris is still valid. Since the receiver doesn't need to download ephemeris again, this is the fastest
startup method.
In the UBX-CFG-RST message, one can force the receiver to reset and clear data, in order to see the effects of
maintaining/losing such a-priori data between restarts. For that, the CFG-RST message offers the navBbrMask
field, where Hot-, Warm- and Coldstarts can be initiated, and also other combinations thereof.
The Reset Type can also be specified. This is not GPS-related, but the way the software restarts the system.
• Hardware Reset uses the on-chip Watchdog, in order to electrically reset the chip. This is an immediate,
asynchronous reset. No Stop events are generated. This is equivalent to pulling the Reset signal on the
receiver.
• Controlled Software Reset terminates all running processes in an orderly manner and, once the system is
idle, restarts operation, reloads its configuration and starts to acquire and track GPS satellites
• Controlled Software Reset (GPS only) only restarts the GPS tasks, without reinitializing the full system or
reloading any stored configuration.
• Controlled GPS Stop stops all GPS tasks. The receiver will not be restarted, but will stop any GPS related
processing.
• Controlled GPS Start starts all GPS tasks.

Geodetic Datum
Predefined Datum
The following, predefined Datum Values are available and can be configured using UBX message CFG-DAT.
For the ellipsoid parameters, see ellipsoid section below. For the rotation and scale parameters, see rotation and
scale section below.
The receiver defaults to WGS84 datum
Geodetic Datum Defined in Firmware
Index Description

0
1
2
3
4
5
6
7
8
9
10

World Geodetic System - 84
World Geodetic System - 72
Earth-90 - GLONASS Coordinate system
Adindan - Mean Solution (Ethiopia & Sudan)
Adindan - Burkina Faso
Adindan - Cameroon
Adindan - Ethiopia
Adindan - Mali
Adindan - Senegal
Adindan - Sudan
Afgooye - Somalia

Short

WGS84
WGS72
ETH90
ADI-M
ADI-E
ADI-F
ADI-A
ADI-C
ADI-D
ADI-B
AFG

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Ellipsoid

Rotation,

Index

Scale

0
23
8
7
7
7
7
7
7
7
21

0
1
0
0
0
0
0
0
0
0
0

dX [m]

dY [m]

0.0
0.0
0.0
-166.0
-118.0
-134.0
-165.0
-123.0
-128.0
-161.0
-43.0

0.0
0.0
0.0
-15.0
-14.0
-2.0
-11.0
-20.0
-18.0
-14.0
-163.0

dZ [m]

0.0
4.5
4.0
204.0
218.0
210.0
206.0
220.0
224.0
205.0
45.0

Receiver Description
Page 9

Geodetic Datum Defined in Firmware continued
Index Description

Short

11 ARC 1950 - Mean (Botswana, Lesotho, Malawi, ARF-M
Swaziland, Zaire, Zambia, Zimbabwe)
12 ARC 1950 - Botswana
ARF-A
13 ARC 1950 - Burundi
ARF-H
14 ARC 1950 - Lesotho
ARF-B
15 ARC 1950 - Malawi
ARF-C
16 ARC 1950 - Swaziland
ARF-D
17 ARC 1950 - Zaire
ARF-E
18 ARC 1950 - Zambia
ARF-F
19 ARC 1950 - Zimbabwe
ARF-G
20 ARC 1960 - Mean (Kenya, Tanzania)
ARS
21 Ayabelle Lighthouse - Djibouti
PHA
22 Bissau - Guinea-Bissau
BID
23 Cape - South Africa
CAP
24 Carthage - Tunisia
CGE
25 Dabola - Guinea
DAL
26 Leigon - Ghana
LEH
27 Liberia 1964
LIB
28 Massawa - Eritrea (Ethiopia)
MAS
29 Merchich - Morocco
MER
30 Minna - Cameroon
MIN-A
31 Minna - Nigeria
MIN-B
32 M'Poraloko - Gabon
MPO
33 North Sahara 1959 - Algeria
NSD
34 Old Egyptian 1907 - Egypt
OEG
35 Point 58 - Mean Solution (Burkina Faso & Niger)
PTB
36 Pointe Noire 1948 - Congo
PTN
37 Schwarzeck - Namibia
SCK
38 Voirol 1960 - Algeria
VOR
39 Ain El Abd 1970 - Bahrain Island
AIN-A
40 Ain El Abd 1970 - Saudi Arabia
AIN-B
41 Djakarta (Batavia)- Sumatra (Indonesia)
BAT
42 Hong Kong 1963 - Hong Kong
HKD
43 Hu-Tzu-Shan - Taiwan
HTN
44 Indian - Bangladesh
IND-B
45 Indian - India & Nepal
IND-I
46 Indian 1954 - Thailand
INF-A
47 Indian 1960 - Vietnam (near 16N)
ING-A
48 Indian 1960 - Con Son Island (Vietnam)
ING-B
49 Indian 1975 - Thailand
INH-A
50 Indonesian 1974
IDN
51 Kandawala - Sri Lanka
KAN
52 Kertau 1948 - West Malaysia & Singapore
KEA
53 Nahrwan - Masirah Island (Oman)
NAH-A
54 Nahrwan - United Arab Emirates
NAH-B
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Ellipsoid

Rotation,

Index

Scale

dX [m]

dY [m]

dZ [m]

7

0

-143.0

-90.0

-294.0

7
7
7
7
7
7
7
7
7
7
20
7
7
7
7
7
5
7
7
7
7
7
17
7
7
5
7
20
20
5
20
20
9
11
9
9
9
9
19
9
13
7
7

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

-138.0
-153.0
-125.0
-161.0
-134.0
-169.0
-147.0
-142.0
-160.0
-79.0
-173.0
-136.0
-263.0
-83.0
-130.0
-90.0
639.0
31.0
-81.0
-92.0
-74.0
-186.0
-130.0
-106.0
-148.0
616.0
-123.0
-150.0
-143.0
-377.0
-156.0
-637.0
282.0
295.0
217.0
198.0
182.0
209.0
-24.0
-97.0
-11.0
-247.0
-249.0

-105.0
-5.0
-108.0
-73.0
-105.0
-19.0
-74.0
-96.0
-6.0
-129.0
253.0
-108.0
6.0
37.0
29.0
40.0
405.0
146.0
-84.0
-93.0
-130.0
-93.0
110.0
-129.0
51.0
97.0
-206.0
-250.0
-236.0
681.0
-271.0
-549.0
726.0
736.0
823.0
881.0
915.0
818.0
-15.0
787.0
851.0
-148.0
-156.0

-289.0
-292.0
-295.0
-317.0
-295.0
-278.0
-283.0
-293.0
-302.0
145.0
27.0
-292.0
431.0
124.0
364.0
88.0
60.0
47.0
115.0
122.0
42.0
310.0
-13.0
165.0
-291.0
-251.0
219.0
-1.0
7.0
-50.0
-189.0
-203.0
254.0
257.0
299.0
317.0
344.0
290.0
5.0
86.0
5.0
369.0
381.0

Receiver Description
Page 10

Geodetic Datum Defined in Firmware continued
Index Description

55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87

Nahrwan - Saudi Arabia
Oman
Qatar National - Qatar
South Asia - Singapore
Timbalai 1948 - Brunei & East Malaysia
(Sarawak & Sabah)
Tokyo - Mean Solution (Japan,Okinawa &
South Korea)
Tokyo - Japan
Tokyo - Okinawa
Tokyo - South Korea
Australian Geodetic 1966 - Australia &
Tasmania
Australian Geodetic 1984 - Australia &
Tasmania
European 1950 - Mean (AU, B, DK, FN, F, G,
GR, I, LUX, NL, N, P, E, S, CH)
European 1950 - Western Europe (AU, DK, FR,
G, NL, CH)
European 1950 - Cyprus
European 1950 - Egypt
European 1950 - England, Wales, Scotland &
Channel Islands
European 1950 - England, Wales, Scotland &
Ireland
European 1950 - Greece
European 1950 - Iran
European 1950 - Italy - Sardinia
European 1950 - Italy - Sicily
European 1950 - Malta
European 1950 - Norway & Finland
European 1950 - Portugal & Spain
European 1950 - Tunisia
European 1979 - Mean Solution (AU, FN, NL, N,
E, S, CH)
Hjorsey 1955 - Iceland
Ireland 1965
Ordnance Survey of GB 1936 - Mean (E, IoM, S,
ShI, W)
Ordnance Survey of GB 1936 - England
Ordnance Survey of GB 1936 - England, Isle of
Man & Wales
Ordnance Survey of GB 1936 - Scotland &
Shetland Isles
Ordnance Survey of GB 1936 - Wales

Short

Ellipsoid

Rotation,

Index

Scale

dX [m]

dY [m]

dZ [m]

NAH-C
FAH
QAT
SOA
TIL

7
7
20
15
10

0
0
0
0
0

-243.0
-346.0
-128.0
7.0
-679.0

-192.0
-1.0
-283.0
-10.0
669.0

477.0
224.0
22.0
-26.0
-48.0

TOY-M

5

0

-148.0

507.0

685.0

TOY-A
TOY-C
TOY-B
AUA

5
5
5
3

0
0
0
0

-148.0
-158.0
-146.0
-133.0

507.0
507.0
507.0
-48.0

685.0
676.0
687.0
148.0

AUG

3

0

-134.0

-48.0

149.0

EUR-M

20

0

-87.0

-98.0

-121.0

EUR-A

20

0

-87.0

-96.0

-120.0

EUR-E
EUR-F
EUR-G

20
20
20

0
0
0

-104.0
-130.0
-86.0

-101.0
-117.0
- 96.0

-140.0
-151.0
-120.0

EUR-K

20

0

-86.0

- 96.0

-120.0

EUR-B
EUR-H
EUR-I
EUR-J
EUR-L
EUR-C
EUR-D
EUR-T
EUS

20
20
20
20
20
20
20
20
20

0
0
0
0
0
0
0
0
0

-84.0
-117.0
-97.0
-97.0
-107.0
-87.0
-84.0
-112.0
-86.0

-95.0
-132.0
-103.0
-88.0
-88.0
-95.0
-107.0
-77.0
-98.0

-130.0
-164.0
-120.0
-135.0
-149.0
-120.0
-120.0
-145.0
-119.0

HJO
IRL
OGB-M

20
2
1

0
0
0

-73.0
506.0
375.0

46.0
-122.0
-111.0

-86.0
611.0
431.0

OGB-A
OGB-B

1
1

0
0

371.0
371.0

-112.0
-111.0

434.0
434.0

OGB-C

1

0

384.0

-111.0

425.0

OGB-D

1

0

370.0

-108.0

434.0

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver Description
Page 11

Geodetic Datum Defined in Firmware continued
Index Description

88
89
90
91
92
93
94
95
96
97
98
99
100
101
102

103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121

Rome 1940 - Sardinia Island
S-42 (Pulkovo 1942) - Hungary
S-JTSK Czechoslavakia (prior to 1 Jan 1993)
Cape Canaveral - Mean Solution (Florida &
Bahamas)
N. American 1927 - Mean Solution (CONUS)
N. American 1927 - Western US
N. American 1927 - Eastern US
N. American 1927 - Alaska (excluding Aleutian
Islands)
N. American 1927 - Aleutian Islands, East of
180W
N. American 1927 - Aleutian Islands, West of
180W
N. American 1927 - Bahamas (excluding San
Salvador Island)
N. American 1927 - San Salvador Island
N. American 1927 - Canada Mean Solution
(including Newfoundland)
N. American 1927 - Alberta & British Columbia
N. American 1927 - Eastern Canada
(Newfoundland, New Brunswick, Nova Scotia &
Quebec)
N. American 1927 - Manitoba & Ontario
N. American 1927 - Northwest Territories &
Saskatchewan
N. American 1927 - Yukon
N. American 1927 - Canal Zone
N. American 1927 - Caribbean
N. American 1927 - Central America
N. American 1927 - Cuba
N. American 1927 - Greenland (Hayes
Peninsula)
N. American 1927 - Mexico
N. American 1983 - Alaska (excluding Aleutian
Islands)
N. American 1983 - Aleutian Islands
N. American 1983 - Canada
N. American 1983 - Mean Solution (CONUS)
N. American 1983 - Hawaii
N. American 1983 - Mexico & Central America
Bogota Observatory - Colombia
Campo Inchauspe 1969 - Argentina
Chua Astro - Paraguay
Corrego Alegre - Brazil

Short

Ellipsoid

Rotation,

Index

Scale

dX [m]

dY [m]

dZ [m]

MOD
SPK
CCD
CAC

20
21
5
6

0
0
0
0

-225.0
28.0
589.0
-2.0

-65.0
-121.0
76.0
151.0

9.0
-77.0
480.0
181.0

NAS-C
NAS-B
NAS-A
NAS-D

6
6
6
6

0
0
0
0

-8.0
-8.0
-9.0
-5.0

160.0
159.0
161.0
135.0

176.0
175.0
179.0
172.0

NAS-V

6

0

-2.0

152.0

149.0

NAS-W

6

0

2.0

204.0

105.0

NAS-Q

6

0

-4.0

154.0

178.0

NAS-R
NAS-E

6
6

0
0

1.0
-10.0

140.0
158.0

165.0
187.0

NAS-F
NAS-G

6
6

0
0

-7.0
-22.0

162.0
160.0

188.0
190.0

NAS-H
NAS-I

6
6

0
0

-9.0
4.0

157.0
159.0

184.0
188.0

NAS-J
NAS-O
NAS-P
NAS-N
NAS-T
NAS-U

6
6
6
6
6
6

0
0
0
0
0
0

-7.0
0.0
-3.0
0.0
-9.0
11.0

139.0
125.0
142.0
125.0
152.0
114.0

181.0
201.0
183.0
194.0
178.0
195.0

NAS-L
NAR-A

6
16

0
0

-12.0
0.0

130.0
0.0

190.0
0.0

NAR-E
NAR-B
NAR-C
NAR-H
NAR-D
BOO
CAI
CHU
COA

16
16
16
16
16
20
20
20
20

0
0
0
0
0
0
0
0
0

-2.0
0.0
0.0
1.0
0.0
307.0
-148.0
-134.0
-206.0

0.0
0.0
0.0
1.0
0.0
304.0
136.0
229.0
172.0

4.0
0.0
0.0
-1.0
0.0
-318.0
90.0
-29.0
-6.0

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver Description
Page 12

Geodetic Datum Defined in Firmware continued
Index Description

122 Prov S. American 1956 - Mean Solution (Bol,
Col, Ecu, Guy, Per & Ven)
123 Prov S. American 1956 - Bolivia
124 Prov S. American 1956 - Northern Chile (near
19S)
125 Prov S. American 1956 - Southern Chile (near
43S)
126 Prov S. American 1956 - Colombia
127 Prov S. American 1956 - Ecuador
128 Prov S. American 1956 - Guyana
129 Prov S. American 1956 - Peru
130 Prov S. American 1956 - Venezuela
131 Prov South Chilean 1963
132 South American 1969 - Mean Solution (Arg,
Bol, Bra, Chi, Col, Ecu, Guy, Par, Per, Tri & Tob,
Ven)
133 South American 1969 - Argentina
134 South American 1969 - Bolivia
135 South American 1969 - Brazil
136 South American 1969 - Chile
137 South American 1969 - Colombia
138 South American 1969 - Ecuador (excluding
Galapagos Islands)
139 South American 1969 - Baltra, Galapagos
Islands
140 South American 1969 - Guyana
141 South American 1969 - Paraguay
142 South American 1969 - Peru
143 South American 1969 - Trinidad & Tobago
144 South American 1969 - Venezuela
145 Zanderij - Suriname
146 Antigua Island Astro 1943 - Antigua, Leeward
Islands
147 Ascension Island 1958
148 Astro Dos 71/4 - St Helena Island
149 Bermuda 1957 - Bermuda Islands
150 Deception Island, Antarctica
151 Fort Thomas 1955 - Nevis, St Kitts, Leeward
Islands
152 Graciosa Base SW 1948 - Faial, Graciosa, Pico,
Sao Jorge, Terceira Islands (Azores)
153 ISTS 061 Astro 1968 - South Georgia Islands
154 L.C. 5 Astro 1961 - Cayman Brac Island
155 Montserrat Island Astro 1958 - Montserrat
Leeward Islands

Short

Ellipsoid

Rotation,

Index

Scale

dX [m]

dY [m]

dZ [m]

PRP-M

20

0

-288.0

175.0

-376.0

PRP-A
PRP-B

20
20

0
0

-270.0
-270.0

188.0
183.0

-388.0
-390.0

PRP-C

20

0

-305.0

243.0

-442.0

PRP-D
PRP-E
PRP-F
PRP-G
PRP-H
HIT
SAN-M

20
20
20
20
20
20
22

0
0
0
0
0
0
0

-282.0
-278.0
-298.0
-279.0
-295.0
16.0
-57.0

169.0
171.0
159.0
175.0
173.0
196.0
1.0

-371.0
-367.0
-369.0
-379.0
-371.0
93.0
-41.0

SAN-A
SAN-B
SAN-C
SAN-D
SAN-E
SAN-F

22
22
22
22
22
22

0
0
0
0
0
0

-62.0
-61.0
-60.0
-75.0
-44.0
-48.0

-1.0
2.0
-2.0
-1.0
6.0
3.0

-37.0
-48.0
-41.0
-44.0
-36.0
-44.0

SAN-J

22

0

-47.0

26.0

-42.0

SAN-G
SAN-H
SAN-I
SAN-K
SAN-L
ZAN
AIA

22
22
22
22
22
20
7

0
0
0
0
0
0
0

-53.0
-61.0
-58.0
-45.0
-45.0
-265.0
-270.0

3.0
2.0
0.0
12.0
8.0
120.0
13.0

-47.0
-33.0
-44.0
-33.0
-33.0
-358.0
62.0

ASC
SHB
BER
DID
FOT

20
20
6
7
7

0
0
0
0
0

-205.0
-320.0
-73.0
260.0
-7.0

107.0
550.0
213.0
12.0
215.0

53.0
-494.0
296.0
-147.0
225.0

GRA

20

0

-104.0

167.0

-38.0

ISG
LCF
ASM

20
6
7

0
0
0

-794.0
42.0
174.0

119.0
124.0
359.0

-298.0
147.0
365.0

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver Description
Page 13

Geodetic Datum Defined in Firmware continued
Index Description

156 Naparima, BWI - Trinidad & Tobago
157 Observatorio Meteorologico 1939 - Corvo and
Flores Islands (Azores)
158 Pico De Las Nieves - Canary Islands
159 Porto Santo 1936 - Porto Santo and Madeira
Islands
160 Puerto Rico - Puerto Rico & Virgin Islands
161 Qornoq - South Greenland
162 Sao Braz - Soa Miguel, Santa Maria Islands
(Azores)
163 Sapper Hill 1943 - East Falkland Island
164 Selvagem Grande 1938 - Salvage Islands
165 Tristan Astro 1968 - Tristan du Cunha
166 Anna 1 Astro 1965 - Cocos Islands
167 Gandajika Base 1970 - Republic of Maldives
168 ISTS 073 Astro 1969 - Diego Garcia
169 Kerguelen Island 1949 - Kerguelen Island
170 Mahe 1971 - Mahe Island
171 Reunion - Mascarene Islands
172 American Samoa 1962 - American Samoa
Islands
173 Astro Beacon E 1945 - Iwo Jima
174 Astro Tern Island (Frig) 1961 - Tern Island
175 Astronomical Station 1952 - Marcus Island
176 Bellevue (IGN) - Efate and Erromango Islands
177 Canton Astro 1966 - Phoenix Islands
178 Chatham Island Astro 1971 - Chatham Island
(New Zeland)
179 DOS 1968 - Gizo Island (New Georgia Islands)
180 Easter Island 1967 - Easter Island
181 Geodetic Datum 1949 - New Zealand
182 Guam 1963 - Guam Island
183 GUX 1 Astro - Guadalcanal Island
184 Indonesian 1974 - Indonesia
185 Johnston Island 1961 - Johnston Island
186 Kusaie Astro 1951 - Caroline Islands, Fed.
States of Micronesia
187 Luzon - Philippines (excluding Mindanao Island)
188 Luzon - Mindanao Island (Philippines)
189 Midway Astro 1961 - Midway Islands
190 Old Hawaiian - Mean Solution
191 Old Hawaiian - Hawaii
192 Old Hawaiian - Kauai
193 Old Hawaiian - Maui
194 Old Hawaiian - Oahu

Short

Ellipsoid

Rotation,

Index

Scale

dX [m]

dY [m]

dZ [m]

NAP
FLO

20
20

0
0

-10.0
-425.0

375.0
-169.0

165.0
81.0

PLN
POS

20
20

0
0

-307.0
-499.0

-92.0
-249.0

127.0
314.0

PUR
QUO
SAO

6
20
20

0
0
0

11.0
164.0
-203.0

72.0
138.0
141.0

-101.0
-189.0
53.0

SAP
SGM
TDC
ANO
GAA
IST
KEG
MIK
RUE
AMA

20
20
20
3
20
20
20
7
20
6

0
0
0
0
0
0
0
0
0
0

-355.0
-289.0
-632.0
-491.0
-133.0
208.0
145.0
41.0
94.0
-115.0

21.0
72.0
-124.0
60.0
438.0 -609.0
-22.0
435.0
-321.0
50.0
-435.0 -229.0
-187.0
103.0
-220.0 -134.0
-948.0 -1262.0
118.0
426.0

ATF
TRN
ASQ
IBE
CAO
CHI

20
20
20
20
20
20

0
0
0
0
0
0

145.0
114.0
124.0
-127.0
298.0
175.0

75.0
-116.0
-234.0
-769.0
-304.0
-38.0

GIZ
EAS
GEO
GUA
DOB
IDN
JOH
KUS

20
20
20
6
20
19
20
20

0
0
0
0
0
0
0
0

230.0 -199.0 -752.0
211.0 147.0
111.0
84.0
-22.0
209.0
-100.0 -248.0
259.0
252.0 -209.0 -751.0
-24.0
-15.0
5.0
189.0
-79.0 -202.0
647.0 1777.0 -1124.0

LUZ-A
LUZ-B
MID
OHA-M
OHA-A
OHA-B
OHA-C
OHA-D

6
6
20
6
6
6
6
6

0
0
0
0
0
0
0
0

-133.0
-133.0
912.0
61.0
89.0
45.0
65.0
58.0

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

-77.0
-79.0
-58.0
-285.0
-279.0
-290.0
-290.0
-283.0

-272.0
-333.0
-25.0
472.0
-375.0
113.0

-51.0
-72.0
1227.0
-181.0
-183.0
-172.0
-190.0
-182.0

Receiver Description
Page 14

Geodetic Datum Defined in Firmware continued
Index Description

195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215

Pitcairn Astro 1967 - Pitcairn Island
Santo (Dos) 1965 - Espirito Santo Island
Viti Levu 1916 - Viti Levu Island (Fiji Islands)
Wake-Eniwetok 1960 - Marshall Islands
Wake Island Astro 1952 - Wake Atoll
Bukit Rimpah - Bangka and Belitung Islands
(Indonesia)
Camp Area Astro - Camp McMurdo Area,
Antarctica
European 1950 - Iraq, Israel, Jordan, Kuwait,
Lebanon, Saudi Arabia & Syria
Gunung Segara - Kalimantan (Indonesia)
Herat North - Afghanistan
Indian - Pakistan
Pulkovo 1942 - Russia
Tananarive Observatory 1925 - Madagascar
Yacare - Uruguay
Krassovsky 1942 - Russia
Lommel Datum 1950 - Belgium & Luxembourg
Reseau National Belge 1972 - Belgium
NTF - Nouvelle Triangulation de la France
Netherlands 1921 - Netherlands
European Datum 1987, IAG RETrig
Subcommision.
Swiss Datum 1903+ (LV95)

Short

Ellipsoid

Rotation,

Index

Scale

dX [m]

dY [m]

dZ [m]

PIT
SAE
MVS
ENW
WAK
BUR

20
20
7
18
20
5

0
0
0
0
0
0

185.0
170.0
51.0
102.0
276.0
-384.0

165.0
42.0
391.0
52.0
-57.0
664.0

42.0
84.0
-36.0
-38.0
149.0
-48.0

CAZ

20

0

-104.0

-129.0

239.0

EUR-S

20

0

-103.0

-106.0

-141.0

GSE
HEN
IND-P
PUK
TAN
YAC
KRA42
BLG50
RNB72
NTF
NL21
ED87

5
20
9
21
20
20
21
20
20
7
5
20

0
0
0
0
0
0
0
0
0
0
0
2

-403.0
-333.0
283.0
28.0
-189.0
-155.0
26.0
-55.0
-104.0
-168.0
719.0
-82.5

684.0
-222.0
682.0
-130.0
-242.0
171.0
-139.0
49.0
80.0
-60.0
47.0
-91.7

41.0
114.0
231.0
-95.0
-91.0
37.0
-80.0
-158.0
-75.0
320.0
640.0
-117.7

CH95

5

0

674.374 15.056 405.346

Ellipsoids
Ellipsoids
Index

0
1
2
3
4
5
6
7
8
9
10
11
12
13

Description

WGS 84
Airy 1830
Modified Airy
Australian National
Bessel 1841 (Namibia)
Bessel 1841
Clarke 1866
Clarke 1880
Earth-90
Everest (India 1830)
Everest (Sabah Sarawak)
Everest (India 1956)
Everest (Malaysia 1969)
Everest (Malay. & Singapore 1948)

Semi Major Axis [m]

6378137.000
6377563.396
6377340.189
6378160.000
6377483.865
6377397.155
6378206.400
6378249.145
6378136.000
6377276.345
6377298.556
6377301.243
6377295.664
6377304.063

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Flattening

298.257223563
299.3249646
299.3249646
298.25
299.1528128
299.1528128
294.9786982
293.465
298.257839303
300.8017
300.8017
300.8017
300.8017
300.8017
Receiver Description
Page 15

Ellipsoids continued
Index Description

14
15
16
17
18
19
20
21
22
23

Everest (Pakistan)
Modified Fischer 1960
GRS 80
Helmert 1906
Hough 1960
Indonesian 1974
International 1924
Krassovsky 1940
South American 1969
WGS 72

Semi Major Axis [m]

6377309.613
6378155.000
6378137.000
6378200.000
6378270.000
6378160.000
6378388.000
6378245.000
6378160.000
6378135.000

Flattening

300.8017
298.3
298.257222101
298.3
297.0
298.247
297.0
298.3
298.25
298.26

Rotation and Scale
Rotation and Scale
Index Description

0
1
2 European Datum 1987 IAG RETrig Subcommision.

Rot X

Rot Y

Rot Z

[seconds]

[seconds]

[seconds]

+0.0000
+0.0000
+0.1338

+0.0000
+0.0000
-0.0625

+0.0000
-0.5540
-0.0470

Scale

0.000
0.220
0.045

Timepulse Configuration
The receiver provides a hardware-synchronized timepulse (Pin 29) with a time pulse (TP) period of 1 ms to 60 s.
The polarity (rising or falling edge) and the pulse duration can be configured. Use the UBX proprietary message
CFG-TP to change the timepulse settings. The UBX-TIM-TP message provides the time information for the next
timepulse, time source and a quantization error.
The CFG-TP message comprises the following parameters defining the hardware-synchronized timepulse:
• pulse interval - time interval between timepulses
• pulse length - duration of the timepulse (time period between rising and falling edge)
• pulse mode - if not disabled the synchronization of timepulse can be configured to be done on rising or
falling edge
• time reference - the reference time source (time base) used for timepulse synchronization and timepulse
time given in TIM-TP output message
• synchronization mode - the timepulse can be configured to be always synchronized and will be available
only in this case. If the timepulse is allowed to be asynchronized it will be available at any time even when
the time is not valid.
• antenna cable delay - the signal delay due to the cable between antenna and receiver
• RF group delay - delay of the signal in the RF module of the u-blox 5 receiver (hard coded)
• user delay - the cable delay from u-blox 5 receiver to the user device plus signal delay of any user
application

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver Description
Page 16

Notes:
• The pulse period must be an integer multiple of 60 seconds.
• The maximum pulse length can’t exceed the pulse period minus 1 microsecond.
• A timepulse is only output when the receiver has determined the time with sufficent accuracy and reliability.
Recommendations:
• When using the timepulse for a timing application it is recommended to calibrate the
RF signal delay against a reference-timing source.
• In order to get the best timing accuracy with the antenna, a fixed accurate position is needed. Once the
receiver is in timing mode, the dynamic model does not influence the timing accuracy.
Example:
The example shows the 1PPS timepulse signal generated according the specific parameters of the CFG-TP
message.

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver Description
Page 17

Receiver Configuration
Configuration Concept
u-blox 5 positioning technology is fully configurable with UBX protocol configuration messages (message class
UBX-CFG). The configuration used by the u-blox 5 GPS core during normal operation is termed "Current
Configuration". The Current Configuration can be changed during normal operation by sending any
UBX-CFG-XXX message to the receiver over an I/O port. The receiver will change its Current Configuration
immediately after receiving the configuration message. The u-blox 5 GPS core always uses only the Current
Configuration.
Unless the Current Configuration is made permanent by using UBX-CFG-CFG as described below, the Current
Configuration will be lost in case of (see message CFG-RST)
• a power cycle
• a hardware reset
• a (complete) controlled software reset
The Current Configuration can be made permanent (stored in a non-volatile memory) by saving it to the
"Permanent Configuration". This is done by sending a UBX-CFG-CFG message with an appropriate saveMask
(UBX-CFG-CFG/save).
The Permanent Configurations are copied to the Current Configuration after start-up or when a UBX-CFG-CFG
message with an appropriate loadMask (UBX-CFG-CFG/load) is sent to the receiver.
The Permanent Configuration can be restored to the receiver's Default Configuration by sending a
UBX-CFG-CFG message with an appropriate clearMask (UBX-CFG-CFG/clear) to the receiver.
This only replaces the Permanent Configuration, not the Current Configuration. To make the receiver operate
with the Default Configuration which was restored to the Permanent Configuration, a UBX-CFG-CFG/load
command must be sent or the receiver must be reset.
The mentioned masks (saveMask, loadMask, clearMask) are 4 byte bit fields . Every bit represents one
configuration sub-section. These sub-sections are defined in section "Organization of the Configuration
NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver Description
Page 18

Sections"). All three masks are part of every UBX-CFG-CFG message. Save, load and clear commands can be
combined in the same message. Order of execution is save, load, clear.
The following diagram illustrates the process:

Organization of the Configuration Sections
The configuration is divided into several sub-sections. Each of these sub-sections corresponds to one or several
UBX-CFG-XXX messages. The sub-section numbers in the following table correspond to the bit position in the
masks mentioned above.
Configuration sub-sections
sub-section

CFG messages

Description

0

UBX-CFG-PRT
UBX-CFG-USB
UBX-CFG-MSG
UBX-CFG-INF
UBX-CFG-NAV5
UBX-CFG-DAT
UBX-CFG-RATE
UBX-CFG-SBAS
UBX-CFG-NMEA
UBX-CFG-TMODE
UBX-CFG-TP
N/A
N/A
UBX-CFG-ANT
N/A

Port and USB settings

1
2
3

4
5
6-9
10
11-31

Message settings (enable/disable, update rate)
Information output settings (Errors, Warnings, Notice, Test etc.)
Navigation Parameter, Receiver Datum, Measurement and Navigation Rate
setting, Timemode settings, SBAS settings, NMEA protocol settings

Timepulse Settings
Reserved for future low power modes
Reserved for EKF (Dead Reckoning) Receivers
Antenna configuration
Reserved

Permanent Configuration Storage Media
The Current Configuration is stored in the receiver's volatile RAM. Hence, any changes made to the Current
Configuration without saving will be lost in the events listed in the section above. By using UBX-CFG-CFG/save,
the selected configuration sub-sections are saved to all non-volatile memories available:
• On-chip BBR (battery backup RAM). In order for the BBR to work, a backup battery must be applied to the
receiver.
• External FLASH memory, where available.
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• External EEPROM (Electrically Erasable Programmable Read-Only Memory), where available via DDC (I2C
compatible).

Receiver Default Configuration
Permanent Configurations can be reset to Default Configurations through a UBX-CFG-CFG/clear message. The
receiver's Default Configuration is determined at system startup. The Default Configuration depends on various
information such as system clock frequency and others. The receiver searches for this information in various
places (memories and configuration pins). Refer to the receiver's data sheet for details.

Power modi for search engine
The receiver determines how and if to search for satellites depending on power configuration (low-level config),
number of satellites tracked and if a valid position could be calculated.

Max. Performance mode
In max. performance mode, the receiver searches for all satellites which are currently not tracked on a channel
and not invisible (as far as information from satellite pre-positioning is available). If no information is available,
the unknown and known-visible satellites are be searched continuously.

Eco mode
In eco mode, if no valid fix could be calculated before, the receiver searches for all satellites with the search
engine as then no assumptions about visibility can be made. After a fix could be calculated, the receiver no
more uses the search engine to search for satellites without pre-positioning information. Pre-positioning
information is available for satellites if orbits for this special SV, and position and time are known at the
receiver. If a confirmed position and time are determined and a sufficient number (more or equal to 4) of
satellites are tracked, the search engine is completely powered off.
Remark that even if the search engine is powered off, satellites can be found and tracked due to
pre-positioning information (slightly slower) or without information at all (significantly slower).
Additionally to these strategic changes, the search engine does not use all resources available in the search
engine, saving computational load and therefore reducing power consumption, but increasing mean time to
find the satellites.

SBAS Configuration Settings Description
SBAS (Satellite Based Augmentation Systems)
SBAS (Satellite Based Augmentation System) is an augmentation technology for GPS, which calculates GPS
integrity and correction data with RIMS (Ranging and Integrity Monitoring Stations) on the ground and uses
geostationary satellites (GEOs) to broadcast GPS integrity and correction data to GPS users. The correction data
is transmitted on the GPS L1 frequency (1575.42 MHz), and therefore no additional receiver is required to
make use of the correction- and integrity data.
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SBAS Principle

There are several compatible SBAS systems available or in development all around the world:
• WAAS (Wide Area Augmentation System) for North America has been in operation since 2003.
• MSAS (Multi-Functional Satellite Augmentation System) for Asia has been in operation since 2007.
• EGNOS (European Geostationary Navigation Overlay Service) is in test mode ESTB (EGNOS satellite test bed).
EGNOS has passed the ORR (Operational Readiness Review) in Q2/2005. Full operation of EGNOS is planned
for 2008.
• GAGAN (GPS Aided Geo Augmented Navigation), developed by the Indian government is in test mode and
expected to be operational by 2010.
Other systems are planned for Canada (CSAS), Africa (EGNOS) and South America.
SBAS support allows u-blox 5 technology to take full advantage of the augmentation systems that are currently
available (WAAS, EGNOS, MSAS), as well as those being tested and planned (such as GAGAN).
With SBAS enabled the user benefits from additional satellites for ranging (navigation). u-blox 5 technology
uses the available SBAS Satellites for navigation just like GPS satellites, if the SBAS satellites offer this service.
To improve position accuracy SBAS uses different types of correction data:
• Fast Corrections for short-term disturbances in GPS signals (due to clock problems, etc).
• Long-term corrections for GPS clock problems, broadcast orbit errors etc.
• Ionosphere corrections for Ionosphere activity
Another benefit is the use of GPS integrity information. In this way SBAS Control stations can ‘disable’ usage of
GPS satellites in case of major GPS satellite problems within a 6 second alarm time. If integrity monitoring is
enabled, u-blox 5 GPS technology will only use satellites, for which integrity information is available.
For more information on SBAS and associated services please refer to
• RTCA/DO-229C (MOPS). Available from www.rtca.org
• gps.faa.gov for information on WAAS and the NSTB
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• www.esa.int for information on EGNOS and the ESTB
• www.essp.be for information about European Satellite Services Provider EEIG is the EGNOS operations
manager.
• www.kasc.go.jp for information on MSAS
SBAS GEO PRN Numbers
GEO identification

Stationed over

Inmarsat AOR-E
Inmarsat AOR-W
ESA Artemis
Inmarsat IND-W
Insat-NAV
Insat-NAV
MTSAT-1R (or MTSAT-2)
Inmarsat IOR
Inmarsat POR
PanAmSat Galaxy XV
MTSAT-2 (or MTSAT-1R)
Telesat Anik F1R

Eastern Africa
Western Africa
Africa (Congo)
Africa (Congo)
(tbd)
(tbd)
Pacific
Indian Ocean
Pacific
133° West
(tbd)
107° West

GPS PRN

120
122
124
126
127
128
129
131
134
135
137
138

SBAS Provider

EGNOS
WAAS
EGNOS
EGNOS
GAGAN
GAGAN
MSAS
EGNOS
WAAS
WAAS
MSAS
WAAS

SBAS Features
This u-blox 5 SBAS implementation is, in accordance with standard RTCA/DO-229C, a class Beta-1
equipment. All timeouts etc. are chosen for the En Route Case. Do not use this equipment under
any circumstances for safety of life applications!
u-blox 5 is capable of receiving multiple SBAS satellites in parallel, even from different SBAS systems (WAAS,
EGNOS, MSAS, etc.). They can be tracked and used for navigation simultaneously. At least three SBAS satellites
can be tracked in parallel. Every SBAS satellite tracked utilizes one vacant GPS receiver tracking channel. Only
the number of receiver channels limits the total number of satellites used. Each SBAS satellite, which broadcasts
ephemeris or almanac information, can be used for navigation, just like a normal GPS satellite.
For receiving correction data, the u-blox 5 GPS receiver automatically chooses the best SBAS satellite as its
primary source. It will select only one since the information received from other SBAS GEOs is redundant and/or
could be inconsistent. The selection strategy is determined by the proximity of the GEOs, the services offered by
the GEO, the configuration of the receiver (Testmode allowed/disallowed, Integrity enabled/disabled) and the
signal link quality to the GEO.
In case corrections are available from the chosen GEO and used in the navigation calculation, the DGPS flag is
set in the receiver’s output protocol messages (see NAV-SOL, NAV-STATUS, NAV-SVINFO, NMEA Position
Fix Flags description).
The most important SBAS feature for accuracy improvement is Ionosphere correction. The measured data from
RIMS stations of a region are combined to a TEC (Total Electron Content) Map. This map is transferred to the
GPS devices via the GEOs to allow a correction of the ionosphere error on each received satellite.
Supported SBAS messages
Message Type

Message Content

Used from GEO

0(0/2)
1
2, 3, 4, 5
6

Test Mode
PRN Mask Assignment
Fast Corrections
Integrity

All
Primary
Primary
Primary

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Supported SBAS messages continued
Message Type

Message Content

Used from GEO

7
9
10
12
17
18
24
25
26

Fast Correction Degradation
GEO Navigation (Ephemeris)
Degradation
Time Offset
GEO Almanacs
Ionosphere Grid Point Assignment
Mixed Fast / Long term Corrections
Long term Corrections
Ionosphere Delays

Primary
All
Primary
Primary
All
Primary
Primary
Primary
Primary

As each GEO services a specific region, the correction signal is only useful within that region. Therefore, mission
planning is crucial to determine the best possible configuration. The different stages (Testmode vs. Operational)
of the various SBAS systems further complicate this task. The following examples show possible scenarios:
Example 1: SBAS Receiver in North America
At the time of writing, the WAAS system is in operational stage, whereas the EGNOS system is still in test mode
(ESTB). Therefore, and especially in the eastern parts of the US, care must be taken in order not to have EGNOS
satellites taking preference over WAAS satellites. This can be achieved by disallowing Test Mode use (this
inhibits EGNOS satellites from being used as a correction data source), but keeping the PRN Mask to have all
SBAS GEOs enabled (which allows EGNOS GEOs to be used for navigation).
Example 2: SBAS Receiver in Europe
At the time of writing, the EGNOS system is still in test mode. To try out EGNOS operation, Testmode usage
must be enabled. Since the WAAS GEO #122 can be received in the western parts of Europe, but since this
GEO does not carry correction data for the European continent, the GEOs from all but the EGNOS system
should be disallowed, using the PRN Mask. It is important to understand that while EGNOS is in test mode,
anything can happen to the EGNOS signals, such as sudden interruption of service or broadcast of invalid or
inconsistent data.
The u-blox 5 GPS receiver always makes use of the best available SBAS correction data.

SBAS Configuration
To configure the SBAS functionalities use the UBX proprietary message UBX–CFG–SBAS
Configuration).

(SBAS

SBAS Configuration parameters
Parameter

Description

Mode - SBAS Subsystem
Mode - Allow test mode usage
Services/Usage - Ranging
Services/Usage - Apply SBAS
correction data
Services/Usage - Apply integrity
information

Enables or disables the SBAS subsystem
Allow / Disallow SBAS usage from satellites in Test Mode (Message 0)
Use the SBAS satellites for navigation
Combined enable/disable switch for Fast-, Long-Term and Ionosphere
Corrections
Use integrity data

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SBAS Configuration parameters continued
Parameter

Description

Number of tracking channels

Sets how many channels are reserved for SBAS tracking (if that many
SBAS signals were acquired). E.g., if this is set to three and five SBAS
SVs are acquired, only three of them will prioritized over available GPS
signals.
Allows to selectively enable/disable SBAS satellite. With this parameter,
for example, one can restrict SBAS usage to WAAS-only

PRN Mask

By default SBAS is enabled with three prioritized SBAS channels and it will use any received SBAS satellites
(except for those in test mode) for navigation, ionosphere parameters and corrections.

NMEA Protocol Configuration
The NMEA protocol on u-blox receivers can be configured to the need of customer applications using
CFG-NMEA. As default all invalid positions out of the defined accuracy range are not reported.
There are two NMEA standards supported. The default NMEA protocol version is 2.3. Alternatively also
Specification version 2.1 can be enabled (for details on how this affect the output refer to section Position Fix
Flags in NMEA Mode ).
NMEA filtering flags
Parameter

Description

Position filtering

If disabled, invalid or old position output is being communicated, but the valid flag
indicates that the data is not current.
If disabled, Masked position data is still being output, but the valid flag will indicate that
the defined accuracy range has been exceeded.
If disabled, the receiver's best knowledge of time is output, even though it might be
wrong.
If disabled, the receiver's best knowledge of date is output, even though it might be
wrong.
If enabled, SBAS satellites are reported according to the NMEA standard.
If disabled, an unfiltered course over ground (COG) output is being output.

Masked position
filtering
Time filtering
Date filtering
SBAS filtering
Track filtering
NMEA flags
Parameter

Description

Compatibility Mode

Some NMEA applications only work with a fixed number of digits behind the decimal
comma. Therefore u-blox receivers offer a compatibility mode to communicate with the
most popular map applications.
u-blox receivers use a sophisticated signal quality detection scheme, in order to produce
the best possible position output. This algorithm considers all SV measurements, and
eventually decides to only use a subset thereof, if it improves the overall position
accuracy. If Consideration mode is enabled, all Satellites, which were considered for
navigation, are being communicated as being used for the position determination. If
Consideration Mode is disabled, only those satellites are marked as being used, which
after the consideration step remained in the position output.

Consideration Mode

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Time Mode Configuration
Introduction
Time Mode is a special stationary GPS receiver mode where the position of the receiver is known and fixed and
only the time is calculated using all available satellites. This mode allows for maximum time accuracy as well as
for single-SV solutions.

Fixed Position
In order to use the Time Mode, the receiver's position must be known as exactly as possible. Either the user
already knows and enters the position, or it is determined using a Survey-in. Errors in the fixed position will
translate into time errors depending on the satellite constellation. Using the TDOP value (see UBX-NAV-DOP)
and assuming a symmetrical 3D position error , the expected time error can be estimated as
time error = tdop * position error
As a rule of thumb the position should be known better than 1m for a time accuracy on the order of
nanoseconds. If only microseconds accuracy is required, a position accuracy of roughly 300m is sufficient.

Survey-in
Survey-in is the procedure of determining a stationary receiver's position prior to using Time Mode by
averaging. The current implementation builds a weighted mean of all valid 3D position solutions. Two stop
criteria can be specified:
• The minimum observation time defines a minimum amount of observation time regardless of the actual
number of valid fixes that were used for the position calculation. Reasonable values range from one day for
high accuracy requirements to a few minutes for coarse position determination.
• The required 3D position standard deviation forces the calculated position to be of at least the given
accuracy. As the position error translates into a time error when using Time Mode (see above), one should
carefully evaluate the time accuracy requirements and the choose an appropriate position accuracy
requirement.
Survey-In ends, when both requirements are met. After Survey-In has finished successfully, the receiver will
automatically enter fixed position Time Mode. The Survey-In status can queried using the UBX-TIM-SVIN
message.

Navigation Configuration Settings Description
Platform settings
u-blox 5 positioning technology supports different dynamic platform models to adjust the navigation engine to
the expected environment. These platform settings can be changed dynamically without doing a power cycle or
reset. It allows a better interpretation of the measurements and hence provides a more accurate position
output. Setting the receiver to an unsuitable platform model for the application environment may reduce the
receiver performance and position accuracy significantly.
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Dynamic Platform Model
Platform

Portable
Stationary
Pedestrian
Automotive
At sea
Airborne <1g
Airborne <2g
Airborne <4g

Description

Default setting. Applications with low accelerations, as any portable devices. Suitable for
most situations.
Used in timing applications (antenna must be stationary) or other stationary applications.
Velocity is constrained to 0 m/s. Zero dynamics assumed.
Applications with low accelerations and low speed, as a pedestrian would move. Assuming
low accelerations.
Used for applications that can be compared with the dynamics of a passenger car.
Assuming low vertical acceleration.
Recommended for applications at sea, with zero vertical velocity. Assuming zero vertical
velocity.
Used for applications that have to handle a higher dynamic range than a car and higher
vertical accelerations. No 2D position fixes supported.
Recommended for typical airborne environment. No 2D position fixes supported.
Only recommended for an extreme dynamic environment. No 2D position fixes supported.

Dynamic platforms designed for high acceleration systems (e.g. airborne <2g) may result in a
greater standard deviation in the reported position.

Navigation Input Filters
The navigation input filters mask the input data of the navigation engine.
These settings are already optimized. It is not recommended that changes to any parameters be
made unless advised by u-blox support engineers.
Navigation Input Filter parameters
Parameter

Description

fixMode

By default, the receiver calculates a 3D position fix if possible but reverts to a 2D position if
necessary (Auto 2D/3D). It is possible to force the receiver to permanently calculate 2D (2D
only) or 3D (3D only) positions.
The fixed altitude is used if fixMode is set to 2D only. A variance greater than zero must be
supplied as well.
Minimum elevation of a satellite above the horizon in order to be used in the navigation
solution. Low elevation satellites may provide degraded accuracy, because of the long
signal path through the atmosphere.
Dead Reckoning limit: The time during which the receiver provides an extrapolated
solution. After the DR timeout has expired, no GPS solution is provided at all.

fixedAlt and
fixedAltVar
minElev

drLimit

Navigation Output Filters
The navigation output filters adjust the valid flag of the relevant NMEA and UBX output messages. Users of the
UBX protocol have additional access to messages containing an accuracy indicator, along with the position,
time and velocity solutions.
• The pDop and pAcc values: The PDOP and Position Accuracy Mask are used to determine if a position
solution is marked valid in the NMEA sentences or if the UBX PosLimit flag is set. A solution is considered
valid, when both PDOP and Accuracy lie below the respective limits.
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• The tDop and tAcc values: The TDOP and Time Accuracy Mask are used to determine when a time pulse
should be allowed. The time pulse is disabled if either TDOP or the time accuracy exceeds its respective limit.
See also the TIM-TP message description.

Static Hold
The Static Hold mode allows the navigation algorithms to decrease the noise in the position output when the
velocity is below a pre-defined ‘Static Hold Threshold’. This reduces the position wander caused by
environmental issues such as multi-path and improves position accuracy especially in stationary applications. By
default, static hold mode is disabled.
If the speed goes below the defined ‘Static Hold Threshold’, the position is kept constant. Once the static hold
mode has been entered, the position and velocity output will be kept constant, until there is evidence of
movement. Such evidence can be velocity, acceleration, changes of the valid flag (e.g. position accuracy
estimate exceeding the Position Accuracy Mask, see also section Navigation Output Filters), position
displacement, etc.

Degraded Navigation
Degraded navigation describes all navigation modes, which use less than 4 satellites.

2D Navigation
If the receiver only has 3 satellites to calculate a position, the navigation algorithm uses a constant altitude to
make up for the missing fourth satellite. When losing a satellite after a successful 3D fix (min. 4 SV available),
the altitude is kept constant to the last known altitude. This is called a 2D fix.
The u-blox 5 positioning technology does not calculate any solution with a number of SVs less than
3. Only u-blox 5 Timing Receivers can calculate timing solution with only one SV when stationary.

Dead Reckoning, Extrapolating Positioning
The implemented extrapolation algorithm kicks in as soon as the receiver no longer achieves a position fix with
a sufficient position accuracy or DOP value (see section Navigation Output Filters). It keeps a fix track (heading
is equal to the last calculated heading) until the Dead Reckoning Timeout is reached. The position is
extrapolated but it’s indicated as “NoFix” (except for NMEA V2.1).
For sensor based Dead Reckoning GPS solutions, u-blox offers Dead Reckoning enabled GPS modules. They
allow high accuracy position solutions for automotive applications at places with poor or no GPS coverage. This
technology relies on additional inputs like a turn rate sensor (gyro) or a speed sensor (odometer or wheel tick).

Receiver Status Monitoring
Messages in this class are used to report the status of the non-GPS-specific parts of the embedded computer
system.
The main purposes are
• Stack- and CPU load (Antaris 4, only)
• Hard- and Software Versions, using MON-VER
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• Status of the Communications Input/Output system
• Status of various Hardware Sections with MON-HW

Input/Output system
The I/O system is a GPS-internal layer where all data input- and output capabilities (such as UART, DDC, SPI,
USB) of the GPS receiver are combined. Each communications task has buffers assigned, where data is queued.
For data originating at the receiver, to be communicated over one or multiple communications queues, the
message MON-TXBUF can be used. This message shows the current and maximum buffer usage, as well as
error conditions.
If too much data is being configured for a certain port's bandwidth (e.g. all UBX messages shall be
output on a UART port with a baud rate of 9600), the buffer will fill up. Once the buffer's space is
exceeded, the receiver will deactivate messages automatically.
Inbound data to the GPS receiver is placed in buffers. These buffers' usage are shown with the message
MON-RXBUF. Further, as data is then decoded within the receiver (e.g. to separate UBX- and NMEA data), the
MON-MSGPP can be used. This message shows, for each port and protocol, how many messages were
successfully received. It also shows, for each port, how many bytes were discarded because they were not in
any of the supported protocol framings.
A target in the context of the I/O system is a I/O protocol. The following table shows the target numbers
used
Target Number assignment
Target #

0
1
2
3
4
5

Electrical Interface

DDC (I2C compatible)
UART 1
UART 2
USB
SPI
reserved

Protocol Number assignment
Protocol #

0
1
2
3
4..7

Protocol Name

UBX Protocol
NMEA Protocol
RTCM Protocol (not supported on u-blox 5)
RAW Protocol (not supported on u-blox 5)
Reserved for future use

Aiding
Introduction
The UBX Message Class AID provides all mechanisms for providing Assiste GPS Data to u-blox GPS receivers,
including AssistNow Online and AssistNow Offline.

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Aiding Data
Following aiding data can be submitted to the receiver:
• Position Position information can be submitted to the receiver using the UBX-AID-INI message. Both,
ECEF X/Y/Z and latitude/longitude/height formats are supported.
• Time The time can either be supplied as an inexact value via the standard communication interfaces,
suffering from latency depending on the baud rate, or using hardware time synchronization where an
accurate time pulse is connected to an external interrupt. Both methods are supported in the UBX-AID-INI
message.
• Frequency It is possible to supply hardware frequency aiding by connecting a continuous signal to an
external interrupt using the UBX-AID-INI message.
• Orbit data Orbit data can be submitted using UBX-AID-ALM and UBX-AID-EPH.
• Additional information UBX-AID-HUI can be used to supply health information, UTC parameters and
ionospheric data to the receiver.

Aiding Sequence
A typical aiding sequence would comprise following steps:
• Power-up the GPS receiver
• Send UBX-AID-INI (time, clock and position) message.
• Send UBX-AID-EPH (ephemeris) message.
• Apply optional hardware time synchronization pulse within 0.5s after (or before, depending on the
configuration in UBX-AID-INI) sending the UBX-AID-INI message if hardware time synchronization is
required. When sending the message before applying the pulse, make sure to allow the GPS receiver to
parse and process the aiding message. The time for parsing depends on the baud rate. The processing time
is 100ms maximum.
• Send optional UBX-AID-HUI (health, UTC and ionosphere parameters) message.
• Send optional UBX-AID-ALM (almanac) message.

AssistNow Online
AssistNow Online is u-blox' end-to-end Assisted GPS (A-GPS) solution that boosts GPS acquisition performance,
bringing Time To First Fix (TTFF) down to seconds. The system works by accessing assistance data such as
Ephemeris, Almanac and accurate time from our Global Reference Network of globally placed GPS receivers.
With A-GPS, the receiver can acquire satellites and provide accurate position data instantly on demand, even
under poor signal conditions.
AssistNow Online makes use of User Plane communication and open standards such as TCP/IP. Therefore, it
works on all standard mobile communication networks that support Internet access, including GPRS, UMTS and
Wireless LAN. No special arrangements need to be made with mobile network operators to enable AssistNow
Online.

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Messaging wise, AssistNow Online consists of Aiding data which deliver Position and Time UBX-AID-INI,
Ephemerides UBX-AID-EPH, Almanac UBX-AID-ALM and Health/UTC/Iono information UBX-AID-HUI

AssistNow Offline
AssistNow Offline is an A-GPS service that boosts GPS acquisition performance, bringing Time To First Fix (TTFF)
down to seconds. Unlike AssistNow Online, this solution enables instant positioning without the need for
connectivity at start-up. The system works by using AlmanacPlus (ALP) differential almanac correction data to
speed up acquisition, enabling a position fix within seconds. Users access the data by means of occasional
Internet downloads, at the user's convenience.

u-blox provides AlmanacPlus data files in different sizes, which contain differential almanac corrections that are
valid for a period of between 1 and 14 days thereafter. Users can download correction data anytime they have
an Internet connection. The GPS receiver stores the downloaded data in the non-volatile Flash EPROM. As an
alternative, a host CPU may store the file, but deliver the data in pieces when requested.
AssistNow Offline works in locations without any wireless connectivity as the correction data files reside in the
receiver or the host. This makes them immediately available upon start-up, eliminating connection set-up
delays, download waiting times and call charges.
The simplest set-up is for GPS receivers including an internal Flash Memory where ALP data can be stored. In
this case, the UBX-AID-ALP message is used.
When the GPS receiver does not contain a Flash Memory, the ALP file must be stored to the host CPU. The GPS
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receiver can the request data from the host when needed. This arrangement is implemented using the
UBX-AID-ALPSRV message.
In both cases, status reporting on ALP data currently available to the GPS receiver can be taken from message
AID-ALP_STAT
AssistNow Offline data are published at http://alp.u-blox.com

Please note that this functionality is only supported on u-blox 5 Firmware 4.0 and above.

Host-based AlmanacPlus Overview
All three versions of AID-ALPSRV messages are used for the case where the storage of an ALP file is not within
the receiver's Flash memory, but on the host, and where the host needs to deliver data to the GPS receiver
repeatedly. This allows support of the AlmanacPlus functionality for GPS receivers which do not have a Flash
memory. For messaging details of an implementation where the data is to reside in the receiver's Flash
memory, see UBX-AID-ALP-DESC
In the following, the GPS receiver is called the client, as it primarily requests data, and the host CPU where the
ALP file is located in its entirety is called the server.
The operation is such that the client sends periodic data requests (the ALP client requests ALPSRV-REQ ) to the
host, and the host should answer them accordingly, as described below at ALPSRV-SRV
For this mechanism to work, the AID-ALPSRV message needs to be activated using the normal
CFG-MSG commands. If it is not activated, no requests are sent out.
The client may attempt to modify the data which is stored on the server, using the ALPSRV-CLI message. The
server may safely ignore such a request, in case the ALP file can not be modified. However, for improved
performance for consecutive receiver restarts, it is recommended to modify the data.
Overview of the three versions of AID-ALPSRV messages
Short Name

ALPSRV-REQ
ALPSRV-SRV
ALPSRV-CLI

Content

ALP client requests AlmanacPlus data from server
ALP server sends AlmanacPlus data to client
ALP client sends AlmanacPlus data to server.

Direction

Client -> Server
Server -> Client
Client -> Server

Message specifics
The three variants of this message always have a header and variable-size data appended within the same
message. The very first field, idSize gives the number of bytes where the header within the UBX payload
ends and data starts.
In case of the ALP client request, the server must assemble a new message according to the
AID-ALPSRV-SRV variant. The header needs to be duplicated for as many as idSize bytes. Additionally, the
server needs to fill in the fileId and dataSize fields. Appended to the idSize-sized header, data must be
added as requested by the client (from offset ofs, for size number of values).

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Range checks
The server needs to perform an out-of-bounds check on the ofs and size fields, as the client may request
data beyond the actually available data. If the client request is within the bounds of available data, the
dataSize field needs to be filled in with 2 x the content of the size field (the size field is in units of 16 bits,
whereas the dataSize field expects number of bytes). If the client request would request data beyond the
limits of the buffer, the data should be reduced accordingly, and this actual number of bytes sent shall be
indicated in the dataSize field

Changing ALP files
The server function would periodically attempt to receive new ALP data from an upstream server, as the result
of an HTTP request or other means of file transfer.
In case a new file becomes available, then the server shall indicate this to the Client. This is the function of the
fileId field.
The server should number ALP files it serves arbitrarily. The only requirement is that the fileId actually is
changed when a new file is being served, and that it does not change as long as the same file is being
changed.
If the client, as a result of a client request, receives a fileId different from the one in earlier requests' replies, it
will reinitialize the ALP engine and request data anew.
Further, if the client attempts to send data to the server, using the ALPSRV-CLI method, it indicates, which
fileId needs to be written. The server shall ignore that request in case the fileId numbers do not match.

Sample Code
u-blox makes available sample code, written in C language, showing a server implementation, serving ALP data
from its file system to a client. Please contact your nearest u-blox Field Application engineer to receive a copy.
Please note that this functionality is only supported on u-blox 5 Firmware 4.0 and above and with
special versions of Antaris 4 receivers.

Flash-based AlmanacPlus Overview
Flash-based AlmanacPlus functionality means that AlmanacPlus data is stored in the program flash memory
connected to the u-blox 5 chip. The task of a server is simply to download the data from an Internet server or
other sources, and then deliver the full file piece by piece to the GPS receiver. This is different to the method
described in UBX-AID-ALPSRV where the file would remain within the host and the GPS receiver would request
chunks from that file when needed.
The message AID-ALP exists in several variants, combining all functionality needed to download data and report
status within one Class/Message ID.

Download Procedure
The following steps are a typical sequence for downloading an ALP file to the receiver:
• The server downloads a copy of a current ALP file, and stores it locally
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Receiver Description
Page 32

• It sends the first N bytes from that file, using the AID-ALP-TX message
• The server awaits a AID-ALP-ACK or AID-ALP-NAK message.
• If can then continue, sending the next N bytes if the message was acknowledged.
• Once all data has been transferred, or a NAK has been received, the server sends an AID-ALP-STOP
message
Please note that
• N should not be larger than ~700 bytes (due to the input buffers on the RS232/USB lines). Smaller values of
N might improve reliability
• N must be a multiple of 2.
• There is no re-send mechanism. If a NAK message is received, the full downloading process must be
restarted.
• There is no explicit checksum, but an implicit one, as the ALP file already includes a checksum to verify
consistency
Overview of the different versions of AID-ALP messages
Short Name

AID-ALP-TX
AID-ALP-STOP
AID-ALP-ACK
AID-ALP-NAK
AID-ALP-STAT

Content

ALP server sends Data to client
ALP server terminates a transfer sequence
ALP client acknowledges successful receipt of data.
ALP client indicates a failed reception of data
ALP client reports status of the ALP data stored in flash memory

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Direction

Server -> Client
Server -> Client
Client -> Server
Client -> Server
Client -> Server

Receiver Description
Page 33

NMEA Protocol
Protocol Overview
NMEA messages sent by the GPS receiver are based on NMEA 0183 Version 2.3. The following picture shows
the structure of a NMEA protocol message.

For further information on the NMEA Standard please refer to NMEA 0183 Standard For Interfacing Marine
Electronic Devices, Version 2.30, March 1, 1998. See http://www.nmea.org/ for ordering instructions.
The NMEA standard allows for proprietary, manufacturer-specific messages to be added. These shall be marked
with a manufacturer mnemonic. The mnemonic assigned to u-blox is UBX and is used for all non-standard
messages. These proprietary NMEA messages therefore have the address field set to PUBX. The first data field
in a PUBX message identifies the message number with two digits.

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NMEA Protocol
Page 34

Latitude and Longitude Format
According to the NMEA Standard, Latitude and Longitude are output in the format Degrees, Minutes and
(Decimal) Fractions of Minutes. To convert to Degrees and Fractions of Degrees, or Degrees, Minutes, Seconds
and Fractions of seconds, the 'Minutes' and 'Fractional Minutes' parts need to be converted. In other words: If
the GPS Receiver reports a Latitude of 4717.112671 North and Longitude of 00833.914843 East, this is
Latitude 47 Degrees, 17.112671 Minutes
Longitude 8 Degrees, 33.914843 Minutes
or
Latitude 47 Degrees, 17 Minutes, 6.76026 Seconds
Longitude 8 Degrees, 33 Minutes, 54.89058 Seconds
or
Latitude 47.28521118 Degrees
Longitude 8.56524738 Degrees

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NMEA Protocol
Page 35

Position Fix Flags in NMEA Mode
The following list shows how u-blox implements the NMEA protocol, and the conditions determining how flags
are set in version 2.3 and above.
NMEA Message: Field

GLL, RMC: Status

No position fix (at

Valid position fix,

Dead reckoning

EKF (only on DR

power-up, after

but user limits

(linear

receivers)

losing satellite lock)

exceeded

extrapolation)

V

V

V

2D position fix

3D position fix

combined GPS/EKF
position fix (only on DR
receivers)

A

A

A

A

6

1/2

1/2

1/2

A=Data VALID, V=Data Invalid (Navigation Receiver Warning)

GGA: Quality Indicator 0

0

6

0=Fix not available/invalid, 1=GPS SPS Mode, Fix valid, 2=Differential GPS, SPS Mode, Fix Valid, 6=Estimated/Dead Reckoning

GSA: Nav Mode

1

1

2

2

2

3

3

E

E

A/D

A/D

A/D

1=Fix Not available, 2=2D Fix, 3=3D Fix

GLL, RMC, VTG: Mode N

N

Indicator
N=No Fix, A=Autonomous GNSS Fix, D=Differential GNSS Fix, E=Estimated/Dead Reckoning Fix

UBX GPSFixOK

0

0

0

1

1

1

1

UBX GPSFix

0

>1

1

1

2

3

4

The following list shows how u-blox implements the NMEA protocol, and the conditions determining how flags
are set in version 2.2 and below.
NMEA Message: Field

GLL, RMC: Status

No position fix (at

Valid position fix,

Dead reckoning

EKF (only on DR

power-up, after

but user limits

(linear

receivers)

losing satellite lock

exceeded

extrapolation)

V

V

A

2D position fix

3D position fix

combined GPS/EKF
position fix (only on DR
receivers)

A

A

A

A

1

1/2

1/2

1/2

2

3

3

A=Data VALID, V=Data Invalid (Navigation Receiver Warning)

GGA: Quality Indicator 0

0

1

0=Fix not available/invalid, 1=GPS SPS Mode, Fix valid, 2=Differential GPS, SPS Mode, Fix Valid

GSA: Nav Mode

1

1

2

2

1=Fix Not available, 2=2D Fix, 3=3D Fix

GLL, RMC, VTG: Mode Indicator. This field is not output by this NMEA version.
UBX GPSFixOK

0

0

0

1

1

1

1

UBX GPSFix

0

>1

1

1

2

3

4

By default the receiver will not output invalid data. In such cases, it will output empty fields.
• A valid position fix is reported as follows:
$GPGLL,4717.11634,N,00833.91297,E,124923.00,A,A*6E
• An invalid position fix (but time valid) is reported as follows:
$GPGLL,,,,,124924.00,V,N*42
• If Time is unknown (e.g. during a cold-start):
$GPGLL,,,,,,V,N*64
In Antaris firmware versions older than 3.0, the receiver did output invalid data and marked it with
the 'Invalid/Valid' Flags. If required, this function can still be enabled in later firmware versions,
using the UBX protocol message CFG-NMEA.
NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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NMEA Protocol
Page 36

NMEA Messages Overview
When configuring NMEA messages using the UBX protocol message CFG-MSG, the Class/Ids shown in the
table shall be used.
Page

Mnemonic

Cls/ID

Description

NMEA Proprietary Messages

Proprietary Messages

52

UBX,00

0xF1 0x00

Lat/Long Position Data

54

UBX,03

0xF1 0x03

Satellite Status

56

UBX,04

0xF1 0x04

Time of Day and Clock Information

58

UBX,40

0xF1 0x40

Set NMEA message output rate

59

UBX,41

0xF1 0x41

Set Protocols and Baudrate

57

UBX

0xF1 0x40

Poll a PUBX message

NMEA Standard Messages

Standard Messages

49

DTM

0xF0 0x0A

Datum Reference

48

GBS

0xF0 0x09

GNSS Satellite Fault Detection

38

GGA

0xF0 0x00

Global positioning system fix data

40

GLL

0xF0 0x01

Latitude and longitude, with time of position fix and status

50

GPQ

0xF0 0x40

Poll message

45

GRS

0xF0 0x06

GNSS Range Residuals

41

GSA

0xF0 0x02

GPS DOP and Active Satellites

46

GST

0xF0 0x07

GNSS Pseudo Range Error Statistics

42

GSV

0xF0 0x03

GPS Satellites in View

43

RMC

0xF0 0x04

Recommended Minimum data

51

TXT

0xF0 0x41

Text Transmission

44

VTG

0xF0 0x05

Course over ground and Ground speed

47

ZDA

0xF0 0x08

Time and Date

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Standard Messages
Standard Messages : i.e. Messages as defined in the NMEA Standard.

GGA
Message

GGA

Description

Global positioning system fix data

Type

Output Message

Comment

The output of this message is dependent on the currently selected datum (Default:
WGS84)
Time and position, together with GPS fixing related data (number of satellites in use, and
the resulting HDOP, age of differential data if in use, etc.).

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x00

17

Message Structure:
$GPGGA,hhmmss.ss,Latitude,N,Longitude,E,FS,NoSV,HDOP,msl,m,Altref,m,DiffAge,DiffStation*cs

Example:
$GPGGA,092725.00,4717.11399,N,00833.91590,E,1,8,1.01,499.6,M,48.0,M,,0*5B
Field

Example

Format

0
1

$GPGGA
092725.00

string
hhmmss.sss

2
3
4

4717.11399
N
00833.91590

5
6

Name

Unit

Description

-

Message ID, GGA protocol header
UTC Time, Current time

-

E
1

$GPGGA
hhmmss.
ss
ddmm.mmmm Latitude
character
N
dddmm.
Longitud
mmmm
e
character
E
digit
FS

7
8
9
10
11
12
13

8
1.01
499.6
M
48.0
M
-

numeric
numeric
numeric
character
numeric
character
numeric

NoSV
HDOP
msl
uMsl
Altref
uSep
DiffAge

m
m
s

14

0

numeric

-

15
16

*5B
-

hexadecimal
character

DiffStat
ion
cs


Latitude, Degrees + minutes, see Format description
N/S Indicator, N=north or S=south
Longitude, Degrees + minutes, see Format
description
E/W indicator, E=east or W=west
Position Fix Status Indicator, See Table below and
Position Fix Flags description
Satellites Used, Range 0 to 12
HDOP, Horizontal Dilution of Precision
MSL Altitude
Units, Meters (fixed field)
Geoid Separation
Units, Meters (fixed field)
Age of Differential Corrections, Blank (Null) fields
when DGPS is not used
Diff. Reference Station ID

-

Checksum
Carriage Return and Line Feed

No.

-

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Page 38

Table Fix Status
Fix Status

Description, see also Position Fix Flags description

0

No Fix / Invalid

1

Standard GPS (2D/3D)

2

Differential GPS

6

Estimated (DR) Fix

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NMEA Protocol
Page 39

GLL
Message

GLL

Description

Latitude and longitude, with time of position fix and status

Type

Output Message

Comment

The output of this message is dependent on the currently selected datum (Default:
WGS84)
-

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x01

(9) or (10)

Message Structure:
$GPGLL,Latitude,N,Longitude,E,hhmmss.ss,Valid,Mode*cs

Example:
$GPGLL,4717.11364,N,00833.91565,E,092321.00,A,A*60
Field

Example

Format

Name

Unit

Description

0
1
2
3

$GPGLL
4717.11364
N
00833.91565
E
092321.00

Message ID, GLL protocol header
Latitude, Degrees + minutes, see Format description
N/S Indicator, hemisphere N=north or S=south
Longitude, Degrees + minutes, see Format
description
E/W indicator, E=east or W=west
UTC Time, Current time

6

A

character

$GPGLL
Latitude
N
Longitud
e
E
hhmmss.
ss
Valid

-

4
5

string
ddmm.mmmm
character
dddmm.
mmmm
character
hhmmss.sss

-

V = Data invalid or receiver warning, A = Data valid.
See Position Fix Flags description

character

Mode

-

Positioning Mode, see Position Fix Flags description

hexadecimal
character

cs


-

Checksum
Carriage Return and Line Feed

No.

-

Start of optional block

7

A

End of optional block

7
8

*60
-

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GSA
Message

GSA

Description

GPS DOP and Active Satellites

Type

Output Message

Comment

• If less than 12 SVs are used for navigation, the remaining fields are left empty. If more
than 12 SVs are used for navigation, only the IDs of the first 12 are output.
• The SV Numbers (Fields 'Sv') are in the range of 1 to 32 for GPS satellites, and 33 to 64
for SBAS satellites (33 = SBAS PRN 120, 34 = SBAS PRN 121, and so on)

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x02

20

Message Structure:
$GPGSA,Smode,FS{,sv},PDOP,HDOP,VDOP*cs

Example:
$GPGSA,A,3,23,29,07,08,09,18,26,28,,,,,1.94,1.18,1.54*0D
Field

Example

Format

Name

Unit

Description

$GPGSA
A
3

string
character
digit

$GPGSA
Smode
FS

-

Message ID, GSA protocol header
Smode, see first table below
Fix status, see second table below and Position Fix
Flags description

numeric

sv

-

Satellite number

numeric
numeric
numeric
hexadecimal
character

PDOP
HDOP
VDOP
cs


-

Position dilution of precision
Horizontal dilution of precision
Vertical dilution of precision
Checksum
Carriage Return and Line Feed

No.

0
1
2

Start of repeated block (12 times)

3 + 29
1*N
End of repeated block

15
16
17
18
19

1.94
1.18
1.54
*0D
-

Table Smode
Smode

Description

M

Manual - forced to operate in 2D or 3D mode

A

Allowed to automatically switch 2D/3D mode

Table Fix Status
Fix Status

Description, see also Position Fix Flags description

1

Fix not available

2

2D Fix

3

3D Fix

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Page 41

GSV
Message

GSV

Description

GPS Satellites in View

Type

Output Message

Comment

The number of satellites in view, together with each PRN (SV ID), elevation and azimuth,
and C/No (Signal/Noise Ratio) value. Only four satellite details are transmitted in one
message. There are up to 4 messages used as indicated in the first field NoMsg.

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x03

7..16

Message Structure:
$GPGSV,NoMsg,MsgNo,NoSv,{,sv,elv,az,cno}*cs

Example:
$GPGSV,3,1,10,23,38,230,44,29,71,156,47,07,29,116,41,08,09,081,36*7F
$GPGSV,3,2,10,10,07,189,,05,05,220,,09,34,274,42,18,25,309,44*72
$GPGSV,3,3,10,26,82,187,47,28,43,056,46*77
Field

Example

Format

Name

Unit

Description

0
1

$GPGSV
3

string
digit

$GPGSV
NoMsg

-

2
3

1
10

digit
numeric

MsgNo
NoSv

-

Message ID, GSV protocol header
Number of messages, total number of GPGSV
messages being output
Number of this message
Satellites in View
Satellite ID

No.

Start of repeated block (1..4 times)

4+
4*N
5+
4*N
6+
4*N
7+
4*N

23

numeric

sv

-

38

numeric

elv

230

numeric

az

44

numeric

cno

degr Elevation, range 0..90
ees
degr Azimuth, range 0..359
ees
dBH C/N0, range 0..99, null when not tracking
z

*7F

hexadecimal

cs

-

Checksum

-

character



-

Carriage Return and Line Feed

End of repeated block

5..
16
6..
16

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RMC
Message

RMC

Description

Recommended Minimum data

Type

Output Message

Comment

The output of this message is dependent on the currently selected datum (Default:
WGS84)
The Recommended Minimum sentence defined by NMEA for GPS/Transit system data.

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x04

15

Message Structure:
$GPRMC,hhmmss,status,latitude,N,longitude,E,spd,cog,ddmmyy,mv,mvE,mode*cs

Example:
$GPRMC,083559.00,A,4717.11437,N,00833.91522,E,0.004,77.52,091202,,,A*57
Field

Example

Format

Name

Unit

Description

0
1

$GPRMC
083559.00

string
hhmmss.sss

-

Message ID, RMC protocol header
UTC Time, Time of position fix

2

A

character

$GPRMC
hhmmss.
ss
Status

3
4
5

4717.11437
N
00833.91522

6
7

E
0.004

ddmm.mmmm
character
dddmm.
mmmm
character
numeric

Latitude
N
Longitud
e
E
Spd

8

77.52

numeric

Cog

9
10

091202
-

ddmmyy
numeric

date
mv

11

-

character

mvE

12
13
14

*57
-

character
hexadecimal
character

mode
cs


No.

-

Status, V = Navigation receiver warning, A = Data
valid, see Position Fix Flags description
Latitude, Degrees + minutes, see Format description
N/S Indicator, hemisphere N=north or S=south
Longitude, Degrees + minutes, see Format
description
E/W indicator, E=east or W=west
knot Speed over ground
s
degr Course over ground
ees
Date in day, month, year format
degr Magnetic variation value, not being output by
ees receiver
Magnetic variation E/W indicator, not being output
by receiver
Mode Indicator, see Position Fix Flags description
Checksum
Carriage Return and Line Feed

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Page 43

VTG
Message

VTG

Description

Course over ground and Ground speed

Type

Output Message

Comment

Velocity is given as Course over Ground (COG) and Speed over Ground (SOG).

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x05

12

Message Structure:
$GPVTG,cogt,T,cogm,M,sog,N,kph,K,mode*cs

Example:
$GPVTG,77.52,T,,M,0.004,N,0.008,K,A*06
Field

Example

Format

Name

Unit

Description

0
1

$GPVTG
77.52

string
numeric

$GPVTG
cogt

Message ID, VTG protocol header
Course over ground (true)

2
3

T
-

character
numeric

T
cogm

4
5

M
0.004

character
numeric

M
sog

6
7

N
0.008

character
numeric

N
kph

8
9
10
11

K
A
*06
-

character
character
hexadecimal
character

K
mode
cs


degr
ees
degr
ees
knot
s
km/
h
-

No.

Fixed field: true
Course over ground (magnetic), not output
Fixed field: magnetic
Speed over ground
Fixed field: knots
Speed over ground
Fixed field: kilometers per hour
Mode Indicator, see Position Fix Flags description
Checksum
Carriage Return and Line Feed

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Page 44

GRS
Message

GRS

Description

GNSS Range Residuals

Type

Output Message

Comment

This messages relates to associated GGA and GSA messages.
If less than 12 SVs are available, the remaining fields are output empty. If more than 12 SVs
are used, only the residuals of the first 12 SVs are output, in order to remain consistent
with the NMEA standard.

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x06

17

Message Structure:
$GPGRS,hhmmss.ss, mode {,residual}*cs

Example:
$GPGRS,082632.00,1,0.54,0.83,1.00,1.02,-2.12,2.64,-0.71,-1.18,0.25,,,*70
Field

Example

Format

Name

Unit

Description

0
1

$GPGRS
082632.00

string
hhmmss.sss

-

Message ID, GRS protocol header
UTC Time, Time of associated position fix

2

1

digit

$GPGRS
hhmmss.
ss
mode

-

Mode (see table below), u-blox receivers will always
output Mode 1 residuals

numeric

residual

m

Range residuals for SVs used in navigation. The SV
order matches the order from the GSA sentence.

hexadecimal
character

cs


-

Checksum
Carriage Return and Line Feed

No.

Start of repeated block (12 times)

3 + 0.54
1*N
End of repeated block

15
16

*70
-

Table Mode
Mode

Description

0

Residuals were used to calculate the position given in the matching GGA sentence.

1

Residuals were recomputed after the GGA position was computed.

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Page 45

GST
Message

GST

Description

GNSS Pseudo Range Error Statistics

Type

Output Message

Comment

-

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x07

11

Message Structure:
$GPGST,hhmmss.ss,range_rms,std_major,std_minor,hdg,std_lat,std_long,std_alt*cs

Example:
$GPGST,082356.00,1.8,,,,1.7,1.3,2.2*7E
Field

Example

Format

Name

Unit

Description

0
1

$GPGST
082356.00

string
hhmmss.sss

-

Message ID, GST protocol header
UTC Time, Time of associated position fix

2

1.8

numeric

m

RMS value of the standard deviation of the ranges

3

-

numeric

4

-

numeric

5

-

numeric

$GPGST
hhmmss.
ss
range_rm
s
std_majo
r
std_mino
r
hdg

6
7
8
9
10

1.7
1.3
2.2
*7E
-

numeric
numeric
numeric
hexadecimal
character

std_lat
std_long
std_alt
cs


No.

m

Standard deviation of semi-major axis, not
supported (empty)
m
Standard deviation of semi-minor axis, not
supported (empty)
degr Orientation of semi-major axis, not supported
ees (empty)
m
Standard deviation of latitude, error in meters
m
Standard deviation of longitude, error in meters
m
Standard deviation of altitude, error in meters
Checksum
Carriage Return and Line Feed

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GPS.G5-X-07036-D
Public Release

NMEA Protocol
Page 46

ZDA
Message

ZDA

Description

Time and Date

Type

Output Message

Comment

-

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x08

9

Message Structure:
$GPZDA,hhmmss.ss,day,month,year,ltzh,ltzn*cs

Example:
$GPZDA,082710.00,16,09,2002,00,00*64
Field

Example

Format

Name

Unit

Description

0
1

$GPZDA
082710.00

string
hhmmss.sss

-

Message ID, ZDA protocol header
UTC Time

2
3

16
09

dd
mm

$GPZDA
hhmmss.
ss
day
month

UTC time: day, 01..31
UTC time: month, 01..12

4
5
6
7
8

2002
00
00
*64
-

yyyy
-xx
zz
hexadecimal
character

year
ltzh
ltzn
cs


day
mon
th
year
-

No.

UTC time: 4 digit year
Local zone hours, not supported (fixed to 00)
Local zone minutes, not supported (fixed to 00)
Checksum
Carriage Return and Line Feed

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Public Release

NMEA Protocol
Page 47

GBS
Message

GBS

Description

GNSS Satellite Fault Detection

Type

Output Message

Comment

This message outputs the results of the Receiver Autonomous Integrity Monitoring
Algorithm (RAIM).
• The fields errlat, errlon and erralt output the standard deviation of the position
calculation, using all satellites which pass the RAIM test successfully.
• The fields errlat, errlon and erralt are only output if the RAIM process passed
successfully (i.e. no or successful Edits happened). These fields are never output if 4 or
fewer satellites are used for the navigation calculation (because - in this case - integrity
can not be determined by the receiver autonomously)
• The fields prob, bias and stdev are only output if at least one satellite failed in the
RAIM test. If more than one satellites fail the RAIM test, only the information for the
worst satellite is output in this message.

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x09

11

Message Structure:
$GPGBS,hhmmss.ss,errlat,errlon,erralt,svid,prob,bias,stddev*cs

Example:
$GPGBS,235503.00,1.6,1.4,3.2,,,,*40
$GPGBS,235458.00,1.4,1.3,3.1,03,,-21.4,3.8*5B
Field

Example

Format

Name

Unit

Description

0
1

$GPGBS
235503.00

string
hhmmss.sss

-

2
3
4
5
6

1.6
1.4
3.2
03
-

numeric
numeric
numeric
numeric
numeric

$GPGBS
hhmmss.
ss
errlat
errlon
erralt
svid
prob

7

-21.4

numeric

bias

m

8
9
10

3.8
*40
-

numeric
hexadecimal
character

stddev
cs


m
-

Message ID, GBS protocol header
UTC Time, Time to which this RAIM sentence
belongs
Expected error in latitude
Expected error in longitude
Expected error in altitude
Satellite ID of most likely failed satellite
Probability of missed detection, no supported
(empty)
Estimate on most likely failed satellite (a priori
residual)
Standard deviation of estimated bias
Checksum
Carriage Return and Line Feed

No.

m
m
m
-

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Public Release

NMEA Protocol
Page 48

DTM
Message

DTM

Description

Datum Reference

Type

Output Message

Comment

This message gives the difference between the currently selected Datum, and the reference
Datum.
If the currently configured Datum is not WGS84 or WGS72, then the field LLL will be set to
999, and the field LSD is set to a variable-lenght string, representing the Name of the
Datum. The list of supported datums can be found in CFG-DAT.
The reference Datum can not be changed and is always set to WGS84.

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x0A

11

Message Structure:
$GPDTM,LLL,LSD,lat,N/S,lon,E/W,alt,RRR*cs

Example:
$GPDTM,W84,,0.0,N,0.0,E,0.0,W84*6F
$GPDTM,W72,,0.00,S,0.01,W,-2.8,W84*4F
$GPDTM,999,CH95,0.08,N,0.07,E,-47.7,W84*1C
Field

Example

Format

Name

Unit

0
1

$GPDTM
W72

string
string

$GPDTM
LLL

-

2

-

string

LSD

3

0.08

numeric

lat

4
5

S
0.07

character
numeric

NS
lon

6
7
8

E
-2.8
W84

character
numeric
string

EW
alt
RRR

9
10

*67
-

hexadecimal
character

cs


Description

No.

Message ID, DTM protocol header
Local Datum Code, W84 = WGS84, W72 = WGS72,
999 = user defined
Local Datum Subdivision Code, This field outputs
the currently selected Datum as a string (see also
note above).
min Offset in Latitude
utes
North/South indicator
min Offset in Longitude
utes
East/West indicator
m
Offset in altitude
Reference Datum Code, W84 = WGS 84. This is the
only supported Reference datum.
Checksum
Carriage Return and Line Feed

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Public Release

NMEA Protocol
Page 49

GPQ
Message

GPQ

Description

Poll message

Type

Input Message

Comment

Polls a standard NMEA message.

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x40

4

Message Structure:
$xxGPQ,sid*cs

Example:
$EIGPQ,RMC*3A
Field

Example

Format

Name

Unit

Description

0

$EIGPQ

string

$xxGPQ

-

1
2
3

RMC
*3A
-

string
hexadecimal
character

sid
cs


-

Message ID, GPQ protocol header, xx = talker
identifier
Sentence identifier
Checksum
Carriage Return and Line Feed

No.

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Public Release

NMEA Protocol
Page 50

TXT
Message

TXT

Description

Text Transmission

Type

Output Message

Comment

This message is not configured through CFG-MSG, but instead through CFG-INF.
This message outputs various information on the receiver, such as power-up screen,
software version etc. This message can be configured using UBX Protocol message CFG-INF

Message Info

ID for CFG-MSG

Number of fields

0xF0 0x41

7

Message Structure:
$GPTXT,xx,yy,zz,ascii data*cs

Example:
$GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
$GPTXT,01,01,02,ANTARIS ATR0620 HW 00000040*67
Field

Example

Format

Name

Unit

Description

0
1

$GPTXT
01

string
numeric

$GPTXT
xx

-

2
3

01
02

numeric
numeric

yy
zz

-

4

www.u-blox.
com
*67
-

string

string

-

Message ID, TXT protocol header
Total number of messages in this transmission, 01..
99
Message number in this transmission, range 01..xx
Text identifier, u-blox GPS receivers specify the
severity of the message with this number.
- 00 = ERROR
- 01 = WARNING
- 02 = NOTICE
- 07 = USER
Any ASCII text

hexadecimal
character

cs


-

Checksum
Carriage Return and Line Feed

No.

5
6

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Public Release

NMEA Protocol
Page 51

Proprietary Messages
Proprietary Messages : i.e. Messages defined by u-blox.

UBX,00
Message

UBX,00

Description

Lat/Long Position Data

Type

Output Message

Comment

The output of this message is dependent on the currently selected datum (Default:
WGS84)
This message contains position solution data. The datum selection may be changed using
the message CFG-DAT.

Message Info

ID for CFG-MSG

Number of fields

0xF1 0x00

23

Message Structure:
$PUBX,00,hhmmss.ss,Latitude,N,Longitude,E,AltRef,NavStat,Hacc,Vacc,SOG,COG,Vvel,ageC,HDOP,VDOP,TDOP
,GU,RU,DR,*cs

Example:
$PUBX,00,081350.00,4717.113210,N,00833.915187,E,546.589,G3,2.1,2.0,0.007,77.52,0.007,,0.92,1.19,0.7
7,9,0,0*5F
Field

Example

Format

Name

Unit

Description

0

$PUBX

string

$PUBX

-

1
2

00
081350.00

numeric
hhmmss.sss

Message ID, UBX protocol header, proprietary
sentence
Propietary message identifier: 00
UTC Time, Current time

No.

6
7
8
9
10
11

ID
hhmmss.
ss
4717.113210 ddmm.mmmm Latitude
N
character
N
00833.915187 dddmm.
Longitud
mmmm
e
E
character
E
546.589
numeric
AltRef
G3
string
NavStat
2.1
numeric
Hacc
2.0
numeric
Vacc
0.007
numeric
SOG

12

77.52

numeric

COG

13
14

0.007
-

numeric
numeric

Vvel
ageC

15

0.92

numeric

HDOP

3
4
5

-

Latitude, Degrees + minutes, see Format description
N/S Indicator, N=north or S=south
Longitude, Degrees + minutes, see Format
description
E/W indicator, E=east or W=west
m
Altitude above user datum ellipsoid.
Navigation Status, See Table below
m
Horizontal accuracy estimate.
m
Vertical accuracy estimate.
km/ Speed over ground
h
degr Course over ground
ees
m/s Vertical velocity, positive=downwards
s
Age of most recent DGPS corrections, empty = none
available
HDOP, Horizontal Dilution of Precision

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GPS.G5-X-07036-D
Public Release

NMEA Protocol
Page 52

UBX,00 continued
Field

Example

Format

Name

Unit

Description

16
17
18

1.19
0.77
9

numeric
numeric
numeric

VDOP
TDOP
GU

-

19

0

numeric

RU

-

20
21
22

0
*5B
-

numeric
hexadecimal
character

DR
cs


-

VDOP, Vertical Dilution of Precision
TDOP, Time Dilution of Precision
Number of GPS satellites used in the navigation
solution
Number of GLONASS satellites used in the
navigation solution
DR used
Checksum
Carriage Return and Line Feed

No.

Table Navigation Status
Navigation Status

Description

NF

No Fix

DR

Predictive Dead Reckoning Solution

G2

Stand alone 2D solution

G3

Stand alone 3D solution

D2

Differential 2D solution

D3

Differential 3D solution

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

NMEA Protocol
Page 53

UBX,03
Message

UBX,03

Description

Satellite Status

Type

Output Message

Comment

The PUBX,03 message contains satellite status information.

Message Info

ID for CFG-MSG

Number of fields

0xF1 0x03

5 + 6*GT

Message Structure:
$PUBX,03,GT{,SVID,s,AZM,EL,SN,LK},*cs

Example:
$PUBX,03,11,23,-,,,45,010,29,-,,,46,013,07,-,,,42,015,08,U,067,31,42,025,10,U,195,33,46,026,18,U,32
6,08,39,026,17,-,,,32,015,26,U,306,66,48,025,27,U,073,10,36,026,28,U,089,61,46,024,15,-,,,39,014*0D
Field

Example

Format

Name

Unit

Description

0

$PUBX

string

$PUBX

-

1
2

03
11

numeric
numeric

ID
GT

-

Message ID, UBX protocol header, proprietary
sentence
Propietary message identifier: 03
Number of GPS satellites tracked

No.

Start of repeated block (GT times)

3+
6*N
4+
6*N
5+
6*N
6+
6*N
7+
6*N
8+
6*N

23

numeric

SVID

-

Satellite PRN number

-

character

s

-

Satellite status, see table below

-

numeric

AZM

Satellite azimuth, range 000..359

-

numeric

EL

45

numeric

SN

010

numeric

LK

degr
ees
degr
ees
dBH
z
s

hexadecimal

cs

-

Checksum

character



-

Carriage Return and Line Feed

Satellite elevation, range 00..90
Signal to noise ratio, range 00..55
Satellite carrier lock time, range 00..255
0 = code lock only
255 = lock for 255 seconds or more

End of repeated block

3 + *0D
6*G
T
4+ 6*G
T

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Public Release

NMEA Protocol
Page 54

Table Satellite Status
Satellite Status

Description

-

Not used

U

Used in solution

e

Available for navigation, but no ephemeris

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Public Release

NMEA Protocol
Page 55

UBX,04
Message

UBX,04

Description

Time of Day and Clock Information

Type

Output Message

Comment

-

Message Info

ID for CFG-MSG

Number of fields

0xF1 0x04

12

Message Structure:
$PUBX,04,hhmmss.ss,ddmmyy,UTC_TOW,week,reserved,Clk_B,Clk_D,PG,*cs

Example:
$PUBX,04,073731.00,091202,113851.00,1196,113851.00,1930035,-2660.664,43,*3C
Field

Example

Format

Name

Unit

Description

0

$PUBX

string

$PUBX

-

1
2

04
073731.00

numeric
hhmmss.sss

-

3
4
5
6
7
8
9

091202
113851.00
1196
113851.00
1930035
-2660.664
43

ddmmyy
numeric
numeric
numeric
numeric
numeric
numeric

ID
hhmmss.
ss
ddmmyy
UTC_TOW
week
reserved
Clk_B
Clk_D
PG

Message ID, UBX protocol header, proprietary
sentence
Propietary message identifier: 04
UTC Time, Current time in hour, minutes, seconds

10
11

*3C
-

hexadecimal
character

cs


-

No.

s
ns
ns/s
ns

UTC Date, day, month, year format
UTC Time of Week
GPS week numer, continues beyond 1023
reserved, for future use
Receiver clock bias
Receiver clock drift
Timepulse Granularity, The quantization error of the
Timepulse pin
Checksum
Carriage Return and Line Feed

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Public Release

NMEA Protocol
Page 56

UBX
Message

UBX

Description

Poll a PUBX message

Type

Input Message

Comment

A PUBX is message is polled by sending the PUBX message without any data fields.

Message Info

ID for CFG-MSG

Number of fields

0xF1 0x40

4

Message Structure:
$PUBX,xx*cs

Example:
$PUBX,04*37
Field

Example

Format

Name

Unit

Description

0

$PUBX

string

$PUBX

-

1
2
3

04
*37
-

numeric
hexadecimal
character

MsgID
cs


-

Message ID, UBX protocol header, proprietary
sentence
Requested PUBX message identifier
Checksum
Carriage Return and Line Feed

No.

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NMEA Protocol
Page 57

UBX,40
Message

UBX,40

Description

Set NMEA message output rate

Type

Set Message

Comment

Set/Get message rate configuration (s) to/from the receiver.
• Send rate is relative to the event a message is registered on. For example, if the rate of a
navigation message is set to 2, the message is sent every second navigation solution.

Message Info

ID for CFG-MSG

Number of fields

0xF1 0x40

11

Message Structure:
$PUBX,40,msgId,rddc,rus1,rus2,rusb,rspi,reserved*cs

Example:
$PUBX,40,GLL,1,0,0,0,0,0*5D
Field

Example

Format

Name

Unit

Description

0

$PUBX

string

$PUBX

-

1
2
3

40
GLL
1

numeric
string
numeric

ID
MsgId
rddc

cycl
es

4

1

numeric

rus1

cycl
es

5

1

numeric

rus2

cycl
es

6

1

numeric

rusb

cycl
es

7

1

numeric

rspi

cycl
es

8
9
10

0
*5D
-

numeric
hexadecimal
character

reserved
cs


-

Message ID, UBX protocol header, proprietary
sentence
Proprietary message identifier
NMEA message identifier
output rate on DDC
- 0 disables that message from being output on this
port
- 1 means that this message is output every epoch
output rate on USART 1
- 0 disables that message from being output on this
port
- 1 means that this message is output every epoch
output rate on USART 2
- 0 disables that message from being output on this
port
- 1 means that this message is output every epoch
output rate on USB
- 0 disables that message from being output on this
port
- 1 means that this message is output every epoch
output rate on SPI
- 0 disables that message from being output on this
port
- 1 means that this message is output every epoch
Reserved, Always fill with 0
Checksum
Carriage Return and Line Feed

No.

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Public Release

NMEA Protocol
Page 58

UBX,41
Message

UBX,41

Description

Set Protocols and Baudrate

Type

Set Message

Comment

-

Message Info

ID for CFG-MSG

Number of fields

0xF1 0x41

9

Message Structure:
$PUBX,41,portId,inProto,outProto,baudrate,autobauding*cs

Example:
$PUBX,41,1,0007,0003,19200,0*25
Field

Example

Format

Name

Unit

0

$PUBX

string

$PUBX

-

1
2

41
1

numeric
numeric

ID
portID

3

0007

hexadecimal

inProto

4

0003

hexadecimal

outProto

5

19200

numeric

baudrate

6

0

numeric

7
8

*25
-

hexadecimal
character

autobaud
ing
cs


Description

No.

Message ID, UBX protocol header, proprietary
sentence
Proprietary message identifier
ID of communication port, for a list of port IDs see
CFG-PRT.
Input protocol mask. Bitmask, specifying which
protocols(s) are allowed for input. For details see
corresponding field in CFG-PRT.
Output protocol mask. Bitmask, specifying which
protocols(s) are allowed for input. For details see
corresponding field in CFG-PRT.
bits/ Baudrate
s
Autobauding: 1=enable, 0=disable (not supported
on u-blox 5, set to 0)
Checksum
Carriage Return and Line Feed

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Public Release

NMEA Protocol
Page 59

UBX Protocol
UBX Protocol Key Features
u-blox GPS receivers use a u-blox proprietary protocol to transmit GPS data to a host computer using
asynchronous RS232 ports. This protocol has the following key features:
• Compact - uses 8 Bit Binary Data.
• Checksum Protected - uses a low-overhead checksum algorithm
• Modular - uses a 2-stage message identifier (Class- and Message ID)

UBX Packet Structure
A basic UBX Packet looks as follows:

•
•
•
•

Every Message starts with 2 Bytes: 0xB5 0x62
A 1 Byte Class Field follows. The Class defines the basic subset of the message
A 1 Byte ID Field defines the message that is to follow
A 2 Byte Length Field is following. Length is defined as being the length of the payload, only. It does not
include Sync Chars, Length Field, Class, ID or CRC fields. The number format of the length field is an
unsigned 16-Bit integer in Little Endian Format.
• The Payload is a variable length field.
• CK_A and CK_B is a 16 Bit checksum whose calculation is defined below.

UBX Class IDs
A Class is a grouping of messages which are related to each other. The following table gives the short names,
description and Class ID Definitions.
Name

Class

Description

NAV
RXM
INF
ACK
CFG
MON

0x01
0x02
0x04
0x05
0x06
0x0A

Navigation Results: Position, Speed, Time, Acc, Heading, DOP, SVs used
Receiver Manager Messages: Satellite Status, RTC Status
Information Messages: Printf-Style Messages, with IDs such as Error, Warning, Notice
Ack/Nack Messages: as replies to CFG Input Messages
Configuration Input Messages: Set Dynamic Model, Set DOP Mask, Set Baud Rate, etc.
Monitoring Messages: Comunication Status, CPU Load, Stack Usage, Task Status

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Public Release

UBX Protocol
Page 60

UBX Class IDs continued
Name

Class

Description

AID
0x0B AssistNow Aiding Messages: Ephemeris, Almanac, other A-GPS data input
TIM
0x0D Timing Messages: Timepulse Output, Timemark Results
All remaining class IDs are reserved.

UBX Payload Definition Rules
Structure Packing
Values are placed in an order that structure packing is not a problem. This means that 2Byte values shall start
on offsets which are a multiple of 2, 4-byte values shall start at a multiple of 4, and so on. This can easily be
achieved by placing the largest values first in the Message payload (e.g. R8), and ending with the smallest (i.e.
one-byters such as U1) values.

Message Naming
Referring to messages is done by adding the class name and a dash in front of the message name. For example,
the ECEF-Message is referred to as NAV-POSECEF. Referring to values is done by adding a dash and the name,
e.g. NAV-POSECEF-X

Number Formats
All multi-byte values are ordered in Little Endian format, unless otherwise indicated.
All floating point values are transmitted in IEEE754 single or double precision. A technical description of the
IEEE754 format can be found in the AnswerBook from the ADS1.x toolkit.
The following table gives information about the various values:
Short

Type

Size (Bytes)

U1
I1
X1
U2
I2
X2
U4
I4

Unsigned Char
Signed Char
Bitfield
Unsigned Short
Signed Short
Bitfield
Unsigned Long
Signed Long

1
1
1
2
2
2
4
4

X4
R4

Bitfield
IEEE 754 Single Precision

4
4

R8

IEEE 754 Double Precision

8

CH

ASCII / ISO 8859.1 Encoding

1

Comment

2's complement

2's complement

2's complement

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Min/Max

Resolution

0..255
-128..127
n/a
0..65535
-32768..32767
n/a
0..4'294'967'295
-2'147'483'648 ..
2'147'483'647
n/a
-1*2^+127 ..
2^+127
-1*2^+1023 ..
2^+1023

1
1
n/a
1
1
n/a
1
1
n/a
~ Value * 2^-24
~ Value * 2^-53

UBX Protocol
Page 61

UBX Checksum
The checksum is calculated over the packet, starting and including the CLASS field, up until, but excluding, the
Checksum Field:

The checksum algorithm used is the 8-Bit Fletcher Algorithm, which is used in the TCP standard (RFC 1145).
This algorithm works as follows:
Buffer[N] contains the data over which the checksum is to be calculated.
The two CK_ values are 8-Bit unsigned integers, only! If implementing with larger-sized integer values, make
sure to mask both CK_A and CK_B with 0xFF after both operations in the loop.
CK_A = 0, CK_B = 0
For(I=0;I> 4) - 4

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INF (0x04)
Information Messages: i.e. Printf-Style Messages, with IDs such as Error, Warning, Notice.
The INF Class is basically an output class that allows the firmware and application code to output strings with a
printf-style call. All INF messages have an associated type to indicate the kind of message.

INF-ERROR (0x04 0x00)
ASCII String output, indicating an error
Message

INF-ERROR

Description

ASCII String output, indicating an error

Type

This message has a variable length payload, representing an ASCII string.

Comment

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x04 0x00

0 + 1*variable

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

char

-

ASCII Character

Format
Start of repeated block (variable times)

N*1

CH

-

End of repeated block

INF-WARNING (0x04 0x01)
ASCII String output, indicating a warning
Message

INF-WARNING

Description

ASCII String output, indicating a warning

Type

This message has a variable length payload, representing an ASCII string.

Comment

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x04 0x01

0 + 1*variable

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

char

-

ASCII Character

Format
Start of repeated block (variable times)

N*1

CH

-

End of repeated block

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INF-NOTICE (0x04 0x02)
ASCII String output, with informational contents
Message

INF-NOTICE

Description

ASCII String output, with informational contents

Type

This message has a variable length payload, representing an ASCII string.

Comment

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x04 0x02

0 + 1*variable

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

char

-

ASCII Character

Format
Start of repeated block (variable times)

N*1

CH

-

End of repeated block

INF-TEST (0x04 0x03)
ASCII String output, indicating test output
Message

INF-TEST

Description

ASCII String output, indicating test output

Type

This message has a variable length payload, representing an ASCII string.

Comment

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x04 0x03

0 + 1*variable

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

char

-

ASCII Character

Format
Start of repeated block (variable times)

N*1

CH

-

End of repeated block

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INF-DEBUG (0x04 0x04)
ASCII String output, indicating debug output
Message

INF-DEBUG

Description

ASCII String output, indicating debug output

Type

This message has a variable length payload, representing an ASCII string.

Comment

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x04 0x04

0 + 1*variable

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

char

-

ASCII Character

Format
Start of repeated block (variable times)

N*1

CH

-

End of repeated block

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ACK (0x05)
Ack/Nack Messages: i.e. as replies to CFG Input Messages.
Messages in this class are sent as a result of a CFG message being received, decoded and processed by the
receiver.

ACK-NAK (0x05 0x00)
Message Not-Acknowledged
Message

ACK-NAK

Description

Message Not-Acknowledged

Type

Answer

Comment

Output upon processing of an input message

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x05 0x00

2

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

clsID
msgID

-

Class ID of the Not-Acknowledged Message
Message ID of the Not-Acknowledged Message

Format

0
1

U1
U1

ACK-ACK (0x05 0x01)
Message Acknowledged
Message

ACK-ACK

Description

Message Acknowledged

Type

Answer

Comment

Output upon processing of an input message

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x05 0x01

2

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

clsID
msgID

-

Class ID of the Acknowledged Message
Message ID of the Acknowledged Message

Format

0
1

U1
U1

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CFG (0x06)
Configuration Input Messages: i.e. Set Dynamic Model, Set DOP Mask, Set Baud Rate, etc..
The CFG Class can be used to configure the receiver and read out current configuration values. Any messages
in Class CFG sent to the receiver are acknowledged (with Message ACK-ACK) if processed successfully, and
rejected (with Message ACK-NAK) if processing the message failed.

CFG-PRT (0x06 0x00)
Polls the configuration of the used I/O Port
Message

CFG-PRT

Description

Polls the configuration of the used I/O Port

Type

Poll Request

Comment

Polls the configuration of the I/O Port on which this message is received

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

0

see below

CK_A CK_B

No payload

Polls the configuration for one I/O Port
Message

CFG-PRT

Description

Polls the configuration for one I/O Port

Type

Poll Request

Comment

Sending this message with a port ID as payload results in having the receiver return the
configuration for the specified port.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

PortID

-

Port Identifier Number (see the other versions of
CFG-PRT for valid values)

Format

0

U1

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Get/Set Port Configuration for UART
Message

CFG-PRT

Description

Get/Set Port Configuration for UART

Type

Get/Set

Comment

Several configurations can be concatenated to one input message. In this case the payload
length can be a multiple of the normal length (see the other versions of CFG-PRT). Output
messages from the module contain only one configuration unit.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

20

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Port Identifier Number (= 1 or 2 for UART ports)
Reserved
Reserved
A bit mask describing the UART mode (see
graphic below)
Baudrate in bits/second
A mask describing which input protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
A mask describing which output protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
Reserved, set to 0
Reserved, set to 0

Format

0
1
2
4

U1
U1
U2
X4

-

portID
res0
res1
mode

-

8
12

U4
X2

-

baudRate
inProtoMask

Bits/s
-

14

X2

-

outProtoMask

-

16
18

X2
U2

-

flags
pad

-

Bitfield mode
This Graphic explains the bits of mode

Name

Description

charLen

Character Length
00 5bit (not supported)
01 6bit (not supported)
10 7bit (supported only with parity)
11 8bit

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Bitfield mode Description continued
Name

Description

parity

000 Even Parity
001 Odd Parity
10X No Parity
X1X Reserved
Number of Stop Bits

nStopBits

00 1 Stop Bit
01 1.5 Stop Bit
10 2 Stop Bit
11 0.5 Stop Bit

Bitfield inProtoMask
This Graphic explains the bits of inProtoMask

Bitfield outProtoMask
This Graphic explains the bits of outProtoMask

Get/Set Port Configuration for USB Port
Message

CFG-PRT

Description

Get/Set Port Configuration for USB Port

Type

Get/Set

Comment

Several configurations can be concatenated to one input message. In this case the payload
length can be a multiple of the normal length (see the other versions of CFG-PRT). Output
messages from the module contain only one configuration unit.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

20

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

portID
res0
res1
res2
res3

-

Port Identifier Number (= 3 for USB port)
Reserved
Reserved
Reserved
Reserved

Format

0
1
2
4
8

U1
U1
U2
U4
U4

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CFG-PRT continued
Byte Offset

Number

Scaling

Name

Unit

Description

A mask describing which input protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
A mask describing which output protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
Reserved, set to 0
Reserved, set to 0

Format

12

X2

-

inProtoMask

-

14

X2

-

outProtoMask

-

16
18

X2
U2

-

flags
pad

-

Bitfield inProtoMask
This Graphic explains the bits of inProtoMask

Bitfield outProtoMask
This Graphic explains the bits of outProtoMask

Get/Set Port Configuration for SPI Port
Message

CFG-PRT

Description

Get/Set Port Configuration for SPI Port

Type

Get/Set

Comment

Several configurations can be concatenated to one input message. In this case the payload
length can be a multiple of the normal length (see the other versions of CFG-PRT). Output
messages from the module contain only one configuration unit.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

20

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Format

0
U1
portID
Port Identifier Number (= 4 for SPI port)
1
U1
res0
Reserved
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CFG-PRT continued
Byte Offset

Number

Scaling

Name

Unit

Description

Reserved
SPI Mode Flags (see graphic below)
Reserved
A mask describing which input protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
A mask describing which output protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
Reserved, set to 0
Reserved, set to 0

Format

2
4
8
12

U2
X4
U4
X2

-

res1
mode
res2
inProtoMask

-

14

X2

-

outProtoMask

-

16
18

X2
U2

-

flags
pad

-

Bitfield mode
This Graphic explains the bits of mode

Name

Description

spiMode

00 SPI Mode 0: CPOL = 0, CPHA = 0
01 SPI Mode 1: CPOL = 0, CPHA = 1
10 SPI Mode 2: CPOL = 1, CPHA = 0
11 SPI Mode 3: CPOL = 1, CPHA = 1

ffCnt

Number of bytes containing 0xFF to receive before switching off reception. Range: 0(mechanism off)-255

Bitfield inProtoMask
This Graphic explains the bits of inProtoMask

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Bitfield outProtoMask
This Graphic explains the bits of outProtoMask

Get/Set Port Configuration for DDC Port
Message

CFG-PRT

Description

Get/Set Port Configuration for DDC Port

Type

Get/Set

Comment

Several configurations can be concatenated to one input message. In this case the payload
length can be a multiple of the normal length (see the other versions of CFG-PRT). Output
messages from the module contain only one configuration unit.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

20

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Port Identifier Number (= 0 for DDC port)
Reserved
Reserved
DDC Mode Flags (see graphic below)
Reserved
A mask describing which input protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
A mask describing which output protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port. (see graphic below)
Reserved, set to 0
Reserved, set to 0

Format

0
1
2
4
8
12

U1
U1
U2
X4
U4
X2

-

portID
res0
res1
mode
res2
inProtoMask

-

14

X2

-

outProtoMask

-

16
18

X2
U2

-

flags
pad

-

Bitfield mode
This Graphic explains the bits of mode

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Bitfield mode Description continued
Name

Description

Name

Description

slaveAddr

Slave address
Range: 0x07 < slaveAddr < 0x78. Bit 0 must be 0

Bitfield inProtoMask
This Graphic explains the bits of inProtoMask

Bitfield outProtoMask
This Graphic explains the bits of outProtoMask

Get/Set Port Configuration for SPI Port
Message

CFG-PRT

Description

Get/Set Port Configuration for SPI Port

Type

Get/Set

Comment

Several configurations can be concatenated to one input message. In this case the payload
length can be a multiple of the normal length (see the other versions of CFG-PRT). Output
messages from the module contain only one configuration unit.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x00

20

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

portID
res0
res1
mode
res2
inProtoMask

-

Port Identifier Number (= 4 for SPI port)
Reserved
Reserved
SPI Mode Flags (see graphic below)
Reserved
A mask describing which input protocols are
active
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port (see graphic below)

Format

0
1
2
4
8
12

U1
U1
U2
X4
U4
X2

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CFG-PRT continued
Byte Offset

Number

Scaling

Name

Unit

Description

A mask describing which output protocols are
active.
Each bit of this mask is used for a protocol.
Through that, multiple protocols can be defined
on a single port (see graphic below)
Reserved, set to 0
Reserved, set to 0

Format

14

X2

-

outProtoMask

-

16
18

X2
U2

-

flags
pad

-

Bitfield mode
This Graphic explains the bits of mode

Name

Description

spiMode

00 SPI Mode 0: CPOL = 0, CPHA = 0
01 SPI Mode 1: CPOL = 0, CPHA = 1
10 SPI Mode 2: CPOL = 1, CPHA = 0
11 SPI Mode 3: CPOL = 1, CPHA = 1

flowControl

0 Flow control disabled
1 Flow control enabled (9-bit mode)

ffCnt

Number of bytes containing 0xFF to receive before switching off reception. Range: 0(mechanism off)-255

Bitfield inProtoMask
This Graphic explains the bits of inProtoMask

Bitfield outProtoMask
This Graphic explains the bits of outProtoMask

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CFG-MSG (0x06 0x01)
Poll a message configuration
Message

CFG-MSG

Description

Poll a message configuration

Type

Poll Request

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x01

2

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

class
msgID

-

Message Class
Message Identifier

Format

0
1

U1
U1

Set Message Rate(s)
Message

CFG-MSG

Description

Set Message Rate(s)

Type

Set/Get

Comment

Set/Get message rate configuration (s) to/from the receiver. See also section How to change
between protocols.
• Send rate is relative to the event a message is registered on. For example, if the rate of a
navigation message is set to 2, the message is sent every second navigation solution.For
configuring NMEA messages, the section NMEA Messages Overview describes Class and
Identifier numbers used.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x01

8

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

class
msgID
rate

-

Message Class
Message Identifier
Send rate on I/O Target (6 Targets)

Format

0
1
2

U1
U1
U1[6]

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Set Message Rate
Message

CFG-MSG

Description

Set Message Rate

Type

Set/Get

Comment

Set message rate configuration for the current target. See also section How to change
between protocols.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x01

3

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

class
msgID
rate

-

Message Class
Message Identifier
Send rate on current Target

Format

0
1
2

U1
U1
U1

CFG-INF (0x06 0x02)
Poll INF message configuration for one protocol
Message

CFG-INF

Description

Poll INF message configuration for one protocol

Type

Poll Request

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x02

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

protocolID

-

Protocol Identifier, identifying the output
protocol for this Poll Request. The following are
valid Protocol Identifiers:
- 0: UBX Protocol
- 1: NMEA Protocol
- 2-255: Reserved

Format

0

U1

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Information message configuration
Message

CFG-INF

Description

Information message configuration

Type

Set/Get

Comment

The value of INFMSG_mask below are that each bit represents one of the INF class
messages (Bit 0 for ERROR, Bit 1 for WARNING and so on.). For a complete list, please see
the Message Class INF. Several configurations can be concatenated to one input message.
In this case the payload length can be a multiple of the normal length. Output messages
from the module contain only one configuration unit. Please note that I/O Targets 0, 1 and
2 correspond to serial ports 0, 1 and 2. I/O target 3 is reserved for future use.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x02

0 + 8*Num

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Protocol Identifier, identifying for which
protocol the configuration is set/get. The
following are valid Protocol Identifiers:
- 0: UBX Protocol
- 1: NMEA Protocol
- 2-255: Reserved
Reserved
Reserved
A bit mask, saying which information messages
are enabled on each I/O target (see graphic
below)

Format
Start of repeated block (Num times)

N*8

U1

-

protocolID

-

1 + 8*N
2 + 8*N
4 + 8*N

U1
U2
X1[4]

-

res0
res1
infMsgMask

-

End of repeated block

Bitfield infMsgMask
This Graphic explains the bits of infMsgMask

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CFG-RST (0x06 0x04)
Reset Receiver / Clear Backup Data Structures
Message

CFG-RST

Description

Reset Receiver / Clear Backup Data Structures

Type

Command

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x04

4

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

BBR Sections to clear. The following Special Sets
apply:
0x0000 Hotstart
0x0001 Warmstart
0xFFFF Coldstart (see graphic below)
Reset Type
- 0x00 - Hardware Reset (Watchdog)
- 0x01 - Controlled Software reset
- 0x02 - Controlled Software reset (GPS only)
- 0x08 - Controlled GPS stop
- 0x09 - Controlled GPS start
Reserved

Format

0

X2

-

navBbrMask

-

2

U1

-

resetMode

-

3

U1

-

res

-

Bitfield navBbrMask
This Graphic explains the bits of navBbrMask

Name

Description

eph
alm
health
klob
pos
clkd
osc
utc
rtc

Ephemeris
Almanach
Health
Klobuchard
Position
Clock Drift
Oscilator Parameter
UTC Correction Parameters
RTC

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CFG-DAT (0x06 0x06)
Poll Datum Setting
Message

CFG-DAT

Description

Poll Datum Setting

Type

Poll Request

Comment

Upon sending of this message, the receiver returns CFG-DAT as defined below

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x06

0

see below

CK_A CK_B

No payload

Set Standard Datum
Message

CFG-DAT

Description

Set Standard Datum

Type

Set

Comment

See section Geodetic Datums for a list of supported Datums

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x06

2

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

datumNum

-

Datum Number

Format

0

U2

Set User-defined Datum
Message

CFG-DAT

Description

Set User-defined Datum

Type

Set

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x06

44

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Semi-major Axis ( accepted range = 6,300,000.0
to 6,500,000.0 metres ).
1.0 / Flattening ( accepted range is 0.0 to 500.0
).
X Axis shift at the origin ( accepted range is +/5000.0 metres ).
Y Axis shift at the origin ( accepted range is +/5000.0 metres ).

Format

0

R8

-

majA

m

8

R8

-

flat

-

16

R4

-

dX

m

20

R4

-

dY

m

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CFG-DAT continued
Byte Offset

Number

Scaling

Name

Unit

Description

Z Axis shift at the origin ( accepted range is +/5000.0 metres ).
Rotation about the X Axis ( accepted range is
+/- 20.0 milli-arc seconds ).
Rotation about the Y Axis ( accepted range is
+/- 20.0 milli-arc seconds ).
Rotation about the Z Axis ( accepted range is +/20.0 milli-arc seconds ).
Scale change ( accepted range is 0.0 to 50.0
parts per million ).

Format

24

R4

-

dZ

m

28

R4

-

rotX

s

32

R4

-

rotY

s

36

R4

-

rotZ

s

40

R4

-

scale

ppm

Get currently selected Datum
Message

CFG-DAT

Description

Get currently selected Datum

Type

Get

Comment

The Parameter datumName is only valid, if datumNum is not equal to -1. In case
datumNum is -1,the receiver is configured for a custom datum. The parameters from majA
to scale are valid for both custom or standard datum formats.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x06

52

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Datum Number according to Geodetic Datums
ASCII String with Datum Mnemonic
Semi-major Axis ( accepted range = 6,300,000.0
to 6,500,000.0 metres ).
1.0 / Flattening ( accepted range is 0.0 to 500.0
).
X Axis shift at the origin ( accepted range is +/5000.0 metres ).
Y Axis shift at the origin ( accepted range is +/5000.0 metres ).
Z Axis shift at the origin ( accepted range is +/5000.0 metres ).
Rotation about the X Axis ( accepted range is
+/- 20.0 milli-arc seconds ).
Rotation about the Y Axis ( accepted range is
+/- 20.0 milli-arc seconds ).
Rotation about the Z Axis ( accepted range is +/20.0 milli-arc seconds ).
Scale change ( accepted range is 0.0 to 50.0
parts per million ).

Format

0
2
8

U2
CH[6]
R8

-

datumNum
datumName
majA

m

16

R8

-

flat

-

24

R4

-

dX

m

28

R4

-

dY

m

32

R4

-

dZ

m

36

R4

-

rotX

s

40

R4

-

rotY

s

44

R4

-

rotZ

s

48

R4

-

scale

ppm

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 96

CFG-TP (0x06 0x07)
Poll TimePulse Parameters
Message

CFG-TP

Description

Poll TimePulse Parameters

Type

Poll Request

Comment

Sending this (empty / no-payload) message to the receiver results in the receiver returning a
message of type CFG-TP with a payload as defined below

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x07

0

see below

CK_A CK_B

No payload

Get/Set TimePulse Parameters
Message

CFG-TP

Description

Get/Set TimePulse Parameters

Type

Get/Set

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x07

20

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Time interval for time pulse
Length of time pulse
Time pulse config setting
+1 = positive
0 = off
-1 = negative
Alignment to reference time:
0 = UTC time,
1 = GPS time
2 = Local time
Bitmask (see graphic below)
Reserved
Antenna Cable Delay

Format

0
4
8

U4
U4
I1

-

interval
length
status

us
us
-

9

U1

-

timeRef

-

10
11
12

U1
U1
I2

-

ns

14
16

I2
I4

-

flags
res
antennaCableD
elay
rfGroupDelay
userDelay

ns
ns

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Receiver RF Group Delay
User Time Function Delay (positive delay results
in earlier pulse)

UBX Protocol
Page 97

Bitfield flags
This Graphic explains the bits of flags

Name

Description

syncMode

0=Time pulse always synchronized and only available if time is valid
1=Time pulse allowed to be asynchronized and available even when time is not valid

CFG-RATE (0x06 0x08)
Poll Navigation/Measurement Rate Settings
Message

CFG-RATE

Description

Poll Navigation/Measurement Rate Settings

Type

Poll Request

Comment

Sending this (empty / no-payload) message to the receiver results in the receiver returning a
message of type CFG-RATE with a payload as defined below

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x08

0

see below

CK_A CK_B

No payload

Navigation/Measurement Rate Settings
Message

CFG-RATE

Description

Navigation/Measurement Rate Settings

Type

Get/Set

Comment

The u-blox positioning technology supports navigation update rates higher or lower than 1
update per second. The calculation of the navigation solution will always be aligned to the
top of a second.
• The update rate has a direct influence on the power consumption. The more fixes that
are required, the more CPU power and communication resources are required.
• For most applications a 1 Hz update rate would be sufficient.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x08

6

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Measurement Rate, GPS measurements are
taken every measRate milliseconds
Navigation Rate, in number of measurement
cycles. On u-blox 5, this parameter cannot be
changed, and is always equals 1.

Format

0

U2

-

measRate

ms

2

U2

-

navRate

cycles

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Public Release

UBX Protocol
Page 98

CFG-RATE continued
Byte Offset

Number

Scaling

Name

Unit

Description

-

timeRef

-

Alignment to reference time: 0 = UTC time, 1 =
GPS time

Format

4

U2

CFG-CFG (0x06 0x09)
Clear, Save and Load configurations
Message

CFG-CFG

Description

Clear, Save and Load configurations

Type

Command

Comment

See the Receiver Configuration chapter for a detailed description on how Receiver
Configuration should be used.The three masks are made up of individual bits, each bit
indicating the sub-section of all configurations on which the corresponding action shall be
carried out. Please note that commands can be combined. The sequence of execution is
Clear, Save, Load

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x09

(12) or (13)

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Mask with configuration sub-sections to Clear
(=Load Default Configurations to Permanent
Configurations in non-volatile memory) (see
graphic below)
Mask with configuration sub-section to Save
(=Save Current Configuration to Non-volatile
Memory), see ID description of clearMask
Mask with configuration sub-sections to Load
(=Load Permanent Configurations from
Non-volatile Memory to Current
Configurations), see ID description of clearMask

Format

0

X4

-

clearMask

-

4

X4

-

saveMask

-

8

X4

-

loadMask

-

-

deviceMask

-

Start of optional block

12

X1

Mask which selects the devices for this
command. (see graphic below)

End of optional block

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Public Release

UBX Protocol
Page 99

Bitfield clearMask
This Graphic explains the bits of clearMask

Name

Description

ioPort
msgConf
infMsg
navConf

I/O Port Assignements, Protocols and Baud Rates (See messages UBX-CFG-PRT and UBX-CFG-USB)
Message Configuration (See message UBX-CFG-MSG)
INF Message Configuration (See UBX-CFG-INF)
NAV Configuration (See UBX-CFG-DAT, UBX-CFG-NAV5, UBX-CFG-RATE, UBX-CFG-SBAS,

UBX-CFG-NMEA, UBX-CFG-TMODE)
Timepulse Configuration (See UBX-CFG-TP)

tpConf
antConf

Used for Receiver Model-specific settings (e.g. UBX-CFG-ANT)

Bitfield deviceMask
This Graphic explains the bits of deviceMask

Name

Description

devBBR
devFlash
devEEPROM

device battery backed RAM
device Flash
device EEPROM

CFG-RXM (0x06 0x11)
RXM configuration
Message

CFG-RXM

Description

RXM configuration

Type

Set/Get

Comment

This message is support with firmware 4.01 or later.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x11

2

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

reserved

-

reserved

Format

0

U1

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Public Release

UBX Protocol
Page 100

CFG-RXM continued
Byte Offset

Number

Scaling

Name

Unit

Description

-

lpMode

-

Low Power Mode
0: Max. performance mode
1-3: reserved
4: Eco mode
5-255: reserved

Format

1

U1

CFG-ANT (0x06 0x13)
Poll Antenna Control Settings
Message

CFG-ANT

Description

Poll Antenna Control Settings

Type

Poll Request

Comment

Sending this (empty / no-payload) message to the receiver results in the receiver returning a
message of type CFG-ANT with a payload as defined below

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x13

0

see below

CK_A CK_B

No payload

Get/Set Antenna Control Settings
Message

CFG-ANT

Description

Get/Set Antenna Control Settings

Type

Get/Set

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x13

4

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

flags
pins

-

Antenna Flag Mask (see graphic below)
Antenna Pin Configuration (see graphic below)

Format

0
2

X2
X2

Bitfield flags
This Graphic explains the bits of flags

Name

Description

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Public Release

UBX Protocol
Page 101

Bitfield flags Description continued
Name

Description

svcs
scd
ocd
pdwnOnSCD
recovery

Enable Antenna Supply Voltage Control Signal
Enable Short Circuit Detection
Enable Open Circuit Detection
Power Down Antenna supply if Short Circuit is detected. (only in combination with Bit 1)
Enable automatic recovery from short state

Bitfield pins
This Graphic explains the bits of pins

Name

Description

pinSwitch
pinSCD
pinOCD
reconfig

PIO-Pin used for switching antenna supply (internal to TIM-LP/TIM-LF)
PIO-Pin used for detecting a short in the antenna supply
PIO-Pin used for detecting open/not connected antenna
if set to one, and this command is sent to the receiver, the receiver will reconfigure the pins as specified.

CFG-SBAS (0x06 0x16)
SBAS Configuration
Message

CFG-SBAS

Description

SBAS Configuration

Type

Command

Comment

This message configures the SBAS receiver subsystem (i.e. WAAS, EGNOS, MSAS).See the
SBAS Configuration Settings Description for a detailed description of how these settings
affect receiver operation.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x16

8

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

SBAS Mode (see graphic below)
SBAS Usage (see graphic below)
Maximum Number of SBAS prioritized tracking
channels (valid range: 0 - 3) to use
Continuation of scanmode bitmask below (see
graphic below)

Format

0
1
2

X1
X1
U1

-

mode
usage
maxSBAS

-

3

X1

-

scanmode2

-

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UBX Protocol
Page 102

CFG-SBAS continued
Byte Offset

Number

Scaling

Name

Unit

Description

-

scanmode1

-

Which SBAS PRN numbers to search for
(Bitmask)
If all Bits are set to zero, auto-scan (i.e. all valid
PRNs) are searched.
Every bit corresponds to a PRN number (see
graphic below)

Format

4

X4

Bitfield mode
This Graphic explains the bits of mode

Name

Description

enabled
test

SBAS Enabled (1) / Disabled (0)
SBAS Testbed: Use data anyhow (1) / Ignore data when in Test Mode (SBAS Msg 0)

Bitfield usage
This Graphic explains the bits of usage

Name

Description

range
diffCorr
integrity

Use SBAS GEOs as a ranging source (for navigation)
Use SBAS Differential Corrections
Use SBAS Integrity Information

Bitfield scanmode2
This Graphic explains the bits of scanmode2

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Public Release

UBX Protocol
Page 103

Bitfield scanmode1
This Graphic explains the bits of scanmode1

CFG-NMEA (0x06 0x17)
Poll the NMEA protocol configuration
Message

CFG-NMEA

Description

Poll the NMEA protocol configuration

Type

Poll Request

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x17

0

see below

CK_A CK_B

No payload

Set/Get the NMEA protocol configuration
Message

CFG-NMEA

Description

Set/Get the NMEA protocol configuration

Type

Set/Get

Comment

Set/Get the NMEA protocol configuration. See section NMEA Protocol Configuration for a
detailed description of the configuration effects on NMEA output.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x17

4

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

filter flags (see graphic below)
0x23 = NMEA version 2.3
0x21 = NMEA version 2.1
Maximum Number of SVs to report in NMEA
protocol.
This does not affect the receiver's operation.
It only limits the number of SVs reported in
NMEA mode (this might be needed with older
mapping applications which only support 8- or
12-channel receivers).
flags (see graphic below)

Format

0
1

X1
U1

-

filter
version

-

2

U1

-

numSV

-

3

X1

-

flags

-

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UBX Protocol
Page 104

Bitfield filter
This Graphic explains the bits of filter

Name

Description

posFilt
mskPosFilt
timeFilt
dateFilt
sbasFilt
trackFilt

disable position filtering
disable masked position filtering
disable time filtering
disable date filtering
enable SBAS filtering
disable track filtering

Bitfield flags
This Graphic explains the bits of flags

Name

Description

compat

enable compatibility mode.
This might be needed for certain applications when customer's NMEA parser expects a fixed number of digits in
position coordinates

consider

enable considering mode.

CFG-USB (0x06 0x1B)
Poll a USB configuration
Message

CFG-USB

Description

Poll a USB configuration

Type

Poll Request

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x1B

0

see below

CK_A CK_B

No payload

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 105

Get/Set USB Configuration
Message

CFG-USB

Description

Get/Set USB Configuration

Type

Get/Set

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x1B

108

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Vendor ID. This field shall only be set to
registered
Vendor IDs. Changing this field requires special
Host drivers.
Product ID. Changing this field requires special
Host drivers.
This field is reserved. Always set to 0
This field is reserved for special use. Always set
to 1
Power consumed by the device in mA

Format

0

U2

-

vendorID

-

2

U2

-

productID

-

4
6

U2
U2

-

reserved1
reserved2

-

8

U2

-

10
12

X2
CH[32] -

powerConsumpt ion
flags
vendorString -

44

CH[32] -

productString -

76

CH[32] -

serialNumber

-

various configuration flags (see graphic below)
String containing the vendor name. 32 ASCII
bytes including 0-termination.
String containing the product name. 32 ASCII
bytes including 0-termination.
String containing the serial number. 32 ASCII
bytes including 0-termination.
Changing the String fields requires special Host
drivers.

Bitfield flags
This Graphic explains the bits of flags

Name

Description

reEnum
powerMode

force re-enumeration
self-powered (1), bus-powered (0)

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UBX Protocol
Page 106

CFG-TMODE (0x06 0x1D)
Poll Time Mode Settings
Message

CFG-TMODE

Description

Poll Time Mode Settings

Type

Poll Request

Comment

This message is available only for timing receivers
Sending this (empty / no-payload) message to the receiver results in the receiver returning a
message of type CFG-TMODE with a payload as defined below

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x1D

0

see below

CK_A CK_B

No payload

Time Mode Settings
Message

CFG-TMODE

Description

Time Mode Settings

Type

Get/Set

Comment

This message is available only for timing receivers
See the Time Mode Description for details.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x1D

28

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Time Transfer Mode:
0
Disabled
1
Survey In
2
Fixed Mode (true position information
required)
3-255 Reserved
Fixed Position ECEF X coordinate
Fixed Position ECEF Y coordinate
Fixed Position ECEF Z coordinate
Fixed position 3D variance
Survey-in minimum duration
Survey-in position variance limit

Format

0

U4

-

timeMode

-

4
8
12
16
20
24

I4
I4
I4
U4
U4
U4

-

fixedPosX
fixedPosY
fixedPosZ
fixedPosVar
svinMinDur
svinVarLimit

cm
cm
cm
mm^2
s
mm^2

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Page 107

CFG-NAVX5 (0x06 0x23)
Poll Navigation Engine Expert Settings
Message

CFG-NAVX5

Description

Poll Navigation Engine Expert Settings

Type

Poll Request

Comment

Sending this (empty / no-payload) message to the receiver results in the receiver returning a
message of type CFG-NAVX5 with a payload as defined below.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x23

0

see below

CK_A CK_B

No payload

Get/Set Navigation Engine Expert Settings
Message

CFG-NAVX5

Description

Get/Set Navigation Engine Expert Settings

Type

Get/Set

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x23

40

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Message version. Current version is 0.
First Parameters Bitmask. Only the flagged
parameters will be applied, unused bits must be
set to 0. (see graphic below)
Second Parameters Bitmask. Currently unused,
must be set to 0.
reserved, set to 0
reserved, set to 0
Minimum number of satellites for navigation
Maximum number of satellites for navigation
Minimum satellite signal level for navigation
reserved, set to 0
Initial Fix must be 3D flag (0=false/1=true)
reserved, set to 0
reserved, set to 0
reserved, set to 0
GPS week rollover number; GPS week numbers
will be set correctly from this week up to 1024
weeks after this week. Setting this to 0 reverts
to firmware default.
reserved, set to 0

Format

0
2

U2
X2

-

version
mask1

-

4

X4

-

mask2

-

8
9
10
11
12
13
14
15
16
17
18

U1
U1
U1
U1
U1
U1
U1
U1
U1
U1
U2

-

res1
res2
minSVs
maxSVs
minCNO
res3
iniFix3D
res4
res5
res6
wknRollover

#SVs
#SVs
dbHz
-

20

U4

-

res7

-

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Page 108

CFG-NAVX5 continued
Byte Offset

Number

Scaling

Name

Unit

Description

-

res8
res9
res10
res11

-

reserved, set to 0
reserved, set to 0
reserved, set to 0
reserved, set to 0

Format

24
28
32
36

U4
U4
U4
U4

Bitfield mask1
This Graphic explains the bits of mask1

Name

Description

minMax
minCno
3dfix
wknRoll

Apply min/max SVs settings
Apply minimum C/N0 setting
Apply initial 3D fix settings
Apply GPS weeknumber rollover settings

CFG-NAV5 (0x06 0x24)
Poll Navigation Engine Settings
Message

CFG-NAV5

Description

Poll Navigation Engine Settings

Type

Poll Request

Comment

Sending this (empty / no-payload) message to the receiver results in the receiver returning a
message of type CFG-NAV5 with a payload as defined below.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x24

0

see below

CK_A CK_B

No payload

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UBX Protocol
Page 109

Get/Set Navigation Engine Settings
Message

CFG-NAV5

Description

Get/Set Navigation Engine Settings

Type

Get/Set

Comment

See the Navigation Configuration Settings Description for a detailed description of how
these settings affect receiver operation.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x06 0x24

36

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Format

0

X2

-

mask

-

2

U1

-

dynModel

-

3

U1

-

fixMode

-

4
8
12

I4
U4
I1

0.01
0.0001
-

fixedAlt
fixedAltVar
minElev

m
m^2
deg

13

U1

-

drLimit

s

14
16
18
20
22

U2
U2
U2
U2
U1

0.1
0.1
-

m
m
cm/s

23
24
28
32

U1
U4
U4
U4

-

pDop
tDop
pAcc
tAcc
staticHoldThr
esh
res1
res2
res3
res4

Parameters Bitmask. Only the masked
parameters will be applied. (see graphic below)
Dynamic Platform model:
-0
Portable
-2
Stationary
-3
Pedestrian
-4
Automotive
-5
Sea
-6
Airborne with >1g Acceleration
-7
Airborne with >2g Acceleration
-8
Airborne with >4g Acceleration
Position Fixing Mode.
- 1: 2D only
- 2: 3D only
- 3: Auto 2D/3D
Fixed altitude (mean sea level) for 2D fix mode.
Fixed altitude variance for 2D mode.
Minimum Elevation for a GNSS satellite to be
used in NAV
Maximum time to perform dead reckoning
(linear extrapolation) in case of GPS signal loss
Position DOP Mask to use
Time DOP Mask to use
Position Accuracy Mask
Time Accuracy Mask
Static hold threshold

-

reserved, set to 0
reserved, set to 0
reserved, set to 0
reserved, set to 0

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Page 110

Bitfield mask
This Graphic explains the bits of mask

Name

Description

dyn
minEl
fixMode
drLim
posMask
timeMask
staticHoldMas
k

Apply dynamic model settings
Apply minimum elevation settings
Apply fix mode settings
Apply DR limit settings
Apply position mask settings
Apply time mask settings
Apply static hold settings

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MON (0x0A)
Monitoring Messages: i.e. Comunication Status, CPU Load, Stack Usage, Task Status.
Messages in this class are sent to report GPS receiver status, such as CPU load, stack usage, I/O subsystem
statistics etc.

MON-IO (0x0A 0x02)
I/O Subsystem Status
Message

MON-IO

Description

I/O Subsystem Status

Type

Periodic/Polled

Comment

The size of the message is determined by the NPRT number of ports the receiver supports, i.
e. on ANTARIS this is always 4, on u-blox 5 the number of ports is 6.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0A 0x02

0 + 20*NPRT

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Number of bytes ever received
Number of bytes ever sent
Number of 100ms timeslots with parity errors
Number of 100ms timeslots with framing errors
Number of 100ms timeslots with overrun errors
Number of 100ms timeslots with break
conditions
Flag is receiver is busy
Flag is transmitter is busy
reserved

Format
Start of repeated block (NPRT times)

N*20
4 + 20*N
8 + 20*N
10 + 20*N
12 + 20*N
14 + 20*N

U4
U4
U2
U2
U2
U2

-

rxBytes
txBytes
parityErrs
framingErrs
overrunErrs
breakCond

bytes
bytes
-

16 + 20*N
17 + 20*N
18 + 20*N

U1
U1
U2

-

rxBusy
txBusy
res

-

End of repeated block

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MON-VER (0x0A 0x04)
Receiver/Software Version
Message

MON-VER

Description

Receiver/Software Version

Type

Answer to Poll

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0A 0x04

40 + 30*Num

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

swVersion
hwVersion

-

Zero-terminated Software Version String
Zero-terminated Hardware Version String

extension

-

Installed Extension Package Version

Format

0
30

CH[30] CH[10] -

Start of repeated block (Num times)

40 + 30*N

CH[30] -

End of repeated block

MON-MSGPP (0x0A 0x06)
Message Parse and Process Status
Message

MON-MSGPP

Description

Message Parse and Process Status

Type

Periodic/Polled

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0A 0x06

120

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Number of successfully parsed messages for
each protocol on target0
Number of successfully parsed messages for
each protocol on target1
Number of successfully parsed messages for
each protocol on target2
Number of successfully parsed messages for
each protocol on target3
Number of successfully parsed messages for
each protocol on target4
Number of successfully parsed messages for
each protocol on target5
Number skipped bytes for each target

Format

0

U2[8]

-

msg1

msgs

16

U2[8]

-

msg2

msgs

32

U2[8]

-

msg3

msgs

48

U2[8]

-

msg4

msgs

64

U2[8]

-

msg5

msgs

80

U2[8]

-

msg6

msgs

96

U4[6]

-

skipped

bytes

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GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 113

MON-RXBUF (0x0A 0x07)
Receiver Buffer Status
Message

MON-RXBUF

Description

Receiver Buffer Status

Type

Periodic/Polled

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0A 0x07

24

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Number of bytes pending in receiver buffer for
each target
Maximum usage receiver buffer during the last
sysmon period for each target
Maximum usage receiver buffer for each target

Format

0

U2[6]

-

pending

bytes

12

U1[6]

-

usage

%

18

U1[6]

-

peakUsage

%

MON-TXBUF (0x0A 0x08)
Transmitter Buffer Status
Message

MON-TXBUF

Description

Transmitter Buffer Status

Type

Periodic/Polled

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0A 0x08

28

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Number of bytes pending in transmitter buffer
for each target
Maximum usage transmitter buffer during the
last sysmon period for each target
Maximum usage transmitter buffer for each
target
Maximum usage of transmitter buffer during
the last sysmon period for all targets
Maximum usage of transmitter buffer for all
targets
Error bitmask (see graphic below)
reserved

Format

0

U2[6]

-

pending

bytes

12

U1[6]

-

usage

%

18

U1[6]

-

peakUsage

%

24

U1

-

tUsage

%

25

U1

-

tPeakusage

%

26
27

X1
U1

-

errors
res

-

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GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 114

Bitfield errors
This Graphic explains the bits of errors

Name

Description

limit
mem
alloc

Buffer limit of corresponding target reached
Memory Allocation error
Allocation error (TX buffer full)

MON-HW (0x0A 0x09)
Hardware Status
Message

MON-HW

Description

Hardware Status

Type

Periodic/Polled

Comment

Status of different aspect of the hardware, such as Antenna, PIO/Peripheral Pins, Noise
Level, Automatic Gain Control (AGC)

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0A 0x09

68

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Mask of Pins Set as Peripheral/PIO
Mask of Pins Set as Bank A/B
Mask of Pins Set as Input/Output
Mask of Pins Value Low/High
Noise Level as measured by the GPS Core
AGC Monitor (counts SIGHI xor SIGLO, range 0
to 8191)
Status of the Antenna Supervisor State Machine
(0=INIT, 1=DONTKNOW, 2=OK, 3=SHORT,
4=OPEN)
Current PowerStatus of Antenna (0=OFF, 1=ON,
2=DONTKNOW)
Flags (see graphic below)
Reserved
Mask of Pins that are used by the Virtual Pin
Manager
Array of Pin Mappings for each of the 25
Physical Pins
Reserved
Mask of Pins Value using the PIO Irq

Format

0
4
8
12
16
18

X4
X4
X4
X4
U2
U2

-

pinSel
pinBank
pinDir
pinVal
noisePerMS
agcCnt

-

20

U1

-

aStatus

-

21

U1

-

aPower

-

22
23
24

X1
U1
X4

-

flags
res1
usedMask

-

28

U1[25]

-

VP

-

53
56

U1[3]
X4

-

res2
pinIrq

-

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Public Release

UBX Protocol
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MON-HW continued
Byte Offset

Number

Scaling

Name

Unit

Description

Mask of Pins Value using the PIO Pull High
Resistor
Mask of Pins Value using the PIO Pull Low
Resistor

Format

60

X4

-

pullH

-

64

X4

-

pullL

-

Bitfield flags
This Graphic explains the bits of flags

Name

Description

rtcCalib

RTC is calibrated

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Public Release

UBX Protocol
Page 116

AID (0x0B)
AssistNow Aiding Messages: i.e. Ephemeris, Almanac, other A-GPS data input.
Messages in this class are used to send aiding data to the receiver.

AID-REQ (0x0B 0x00)
Sends a poll (AID-DATA) for all GPS Aiding Data
Message

AID-REQ

Description

Sends a poll (AID-DATA) for all GPS Aiding Data

Type

Virtual

Comment

AID-REQ is not a message but a placeholder for configuration purposes.
If the virtual AID-REQ is configured to be output (see CFG-MSG), the receiver will output a
request for aiding data (AID-DATA) after a start-up if its internally stored data (position,
time, ephemeris, almanac) don't allow it to perform a hot start.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x00

0

see below

CK_A CK_B

No payload

AID-INI (0x0B 0x01)
Poll GPS Initial Aiding Data
Message

AID-INI

Description

Poll GPS Initial Aiding Data

Type

Poll Request

Comment

This message has an empty payload!
-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x01

0

see below

CK_A CK_B

No payload

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GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 117

Aiding position, time, frequency, clock drift
Message

AID-INI

Description

Aiding position, time, frequency, clock drift

Type

Polled

Comment

This message contains position, time and clock drift information. The position can be input
in either the ECEF X/Y/Z coordinate system or as lat/lon/height. The time can either be input
as inexact value via the standard communication interface, suffering from latency
depending on the baudrate, or using harware time synchronization where an accuracte
time pulse is input on the external interrupts. It is also possible to supply hardware
frequency aiding by connecting a continuous signal to an external interrupt.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x01

48

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

cm_or_
deg*1e
7
cm_or_
deg*1e
7
cm

WGS84 ECEF X coordinate or latitude,
depending on flags below

Format

0

I4

-

ecefXOrLat

4

I4

-

ecefYOrLon

8

I4

-

ecefZOrAlt

12
16
18
20
24
28
32
36

U4
X2
U2
U4
I4
U4
U4
I4

-

40

U4

-

44

X4

-

WGS84 ECEF Y coordinate or longitude,
depending on flags below

WGS84 ECEF Z coordinate or altitude,
depending on flags below
posAcc
cm
Position accuracy (stddev)
tmCfg
Time mark configuration (see graphic below)
wn
Actual week number
tow
ms
Actual time of week
towNs
ns
Sub-millisecond part of time of week
tAccMs
ms
Milliseconds part of time accuracy
tAccNs
ns
Nanoseconds part of time accuracy
clkDOrFreq
ns/s_or Clock drift or frequency, depending on flags
_Hz
below
clkDAccOrFreq ns/s_or Accuracy of clock drift or frequency, depending
Acc
_ppm
on flags below
flags
Bitmask with the following flags (see graphic
below)

Bitfield tmCfg
This Graphic explains the bits of tmCfg

Name

Description

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UBX Protocol
Page 118

Bitfield tmCfg Description continued
Name

Description

fEdge
tm1
f1

use falling edge (default rising)
time mark on extint 1 (default extint 0)
frequency on extint 1 (default extint 0)

Bitfield flags
This Graphic explains the bits of flags

Name

Description

pos
time
clockD
tp
clockF
lla
altInv
prevTm

Position is valid
Time is valid
Clock drift data contains valid clock drift, must not be set together with clockF
Use time pulse
Clock drift data contains valid frequency, must not be set together with clockD
Position is given in LAT/LON/ALT (default is ECEF)
Altitude is not valid, in case lla was set
Use time mark received before AID-INI message (default uses mark received after message)

AID-HUI (0x0B 0x02)
Poll GPS Health, UTC and ionosphere parameters
Message

AID-HUI

Description

Poll GPS Health, UTC and ionosphere parameters

Type

Poll Request

Comment

This message has an empty payload!
-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x02

0

see below

CK_A CK_B

No payload

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GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 119

GPS Health, UTC and ionosphere parameters
Message

AID-HUI

Description

GPS Health, UTC and ionosphere parameters

Type

Input/Output Message

Comment

This message contains a health bit mask, UTC time and Klobuchar parameters. For more
information on these parameters, please see the ICD-GPS-200 documentation.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x02

72

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

-

Description

Format

0

X4

-

health

4
12
20
24
26

R8
R8
I4
I2
I2

-

utcA1
utcA0
utcTOW
utcWNT
utcLS

28

I2

-

utcWNF

30

I2

-

utcDN

32

I2

-

utcLSF

34

I2

-

utcSpare

36
40

R4
R4

-

klobA0
klobA1

44

R4

-

klobA2

48

R4

-

klobA3

52
56

R4
R4

-

klobB0
klobB1

60

R4

-

klobB2

64

R4

-

klobB3

68

X4

-

flags

Bitmask, every bit represenst a GPS SV (1-32). If
the bit is set the SV is healthy.
UTC - parameter A1
UTC - parameter A0
UTC - reference time of week
UTC - reference week number
UTC - time difference due to leap seconds
before event
UTC - week number when next leap second
event occurs
UTC - day of week when next leap second event
occurs
UTC - time difference due to leap seconds after
event
UTC - Spare to ensure structure is a multiple of
4 bytes
s
Klobuchar - alpha 0
s/semici Klobuchar - alpha 1
rcle
s/semici Klobuchar - alpha 2
rcle^2
s/semici Klobuchar - alpha 3
rcle^3
s
Klobuchar - beta 0
s/semici Klobuchar - beta 1
rcle
s/semici Klobuchar - beta 2
rcle^2
s/semici Klobuchar - beta 3
rcle^3
flags (see graphic below)

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GPS.G5-X-07036-D
Public Release

UBX Protocol
Page 120

Bitfield flags
This Graphic explains the bits of flags

Name

Description

health
utc
klob

Healthmask field in this message is valid
UTC parameter fields in this message are valid
Klobuchar parameter fields in this message are valid

AID-DATA (0x0B 0x10)
Polls all GPS Initial Aiding Data
Message

AID-DATA

Description

Polls all GPS Initial Aiding Data

Type

Poll

Comment

If this poll is received, the messages AID-INI, AID-HUI, AID-EPH and AID-ALM are sent.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x10

0

see below

CK_A CK_B

No payload

AID-ALM (0x0B 0x30)
Poll GPS Aiding Almanach Data
Message

AID-ALM

Description

Poll GPS Aiding Almanach Data

Type

Poll Request

Comment

This message has an empty payload!
Poll GPS Aiding Data (Almanach) for all 32 SVs by sending this message to the receiver
without any payload. The receiver will return 32 messages of type AID-ALM as defined
below.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x30

0

see below

CK_A CK_B

No payload

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Public Release

UBX Protocol
Page 121

Poll GPS Aiding Almanach Data for a SV
Message

AID-ALM

Description

Poll GPS Aiding Almanach Data for a SV

Type

Poll Request

Comment

Poll GPS Aiding Data (Almanach) for an SV by sending this message to the receiver. The
receiver will return one message of type AID-ALM as defined below.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x30

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

svid

-

SV ID for which the receiver shall return
its Almanach Data (Valid Range: 1 .. 32 or 51,
56, 63).

Format

0

U1

GPS Aiding Almanach Input/Output Message
Message

AID-ALM

Description

GPS Aiding Almanach Input/Output Message

Type

Input/Output Message

Comment

• If the WEEK Value is 0, DWRD0 to DWRD7 are not sent as the almanach is not available
for the given SV.
• DWORD0 to DWORD7 contain the 8 words following the Hand-Over Word ( HOW )
from the GPS navigation message, either pages 1 to 24 of sub-frame 5 or pages 2 to 10
of subframe 4. See IS-GPS-200 for a full description of the contents of the Almanac
pages.
• In DWORD0 to DWORD7, the parity bits have been removed, and the 24 bits of data are
located in Bits 0 to 23. Bits 24 to 31 shall be ignored.
• Example: Parameter e (Eccentricity) from Almanach Subframe 4/5, Word 3, Bits 69-84
within the subframe can be found in DWRD0, Bits 15-0 whereas Bit 0 is the LSB.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x30

(8) or (40)

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Format

0

U4

-

svid

-

4

U4

-

week

-

SV ID for which this
Almanach Data is (Valid Range: 1 .. 32 or 51,
56, 63).
Issue Date of Almanach (GPS week number)

-

dwrd

-

Almanach Words

Start of optional block

8

U4[8]

End of optional block

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Public Release

UBX Protocol
Page 122

AID-EPH (0x0B 0x31)
Poll GPS Aiding Ephemeris Data
Message

AID-EPH

Description

Poll GPS Aiding Ephemeris Data

Type

Poll Request

Comment

This message has an empty payload!
Poll GPS Aiding Data (Ephemeris) for all 32 SVs by sending this message to the receiver
without any payload. The receiver will return 32 messages of type AID-EPH as defined
below.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x31

0

see below

CK_A CK_B

No payload

Poll GPS Aiding Ephemeris Data for a SV
Message

AID-EPH

Description

Poll GPS Aiding Ephemeris Data for a SV

Type

Poll Request

Comment

Poll GPS Constellation Data (Ephemeris) for an SV by sending this message to the receiver.
The receiver will return one message of type AID-EPH as defined below.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x31

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

svid

-

SV ID for which the receiver shall return
its Ephemeris Data (Valid Range: 1 .. 32).

Format

0

U1

GPS Aiding Ephemeris Input/Output Message
Message

AID-EPH

Description

GPS Aiding Ephemeris Input/Output Message

Type

Input/Output Message

Comment

• SF1D0 to SF3D7 is only sent if ephemeris is available for this SV. If not, the payload may
be reduced to 8 Bytes, or all bytes are set to zero, indicating that this SV Number does
not have valid ephemeris for the moment.
• SF1D0 to SF3D7 contain the 24 words following the Hand-Over Word ( HOW ) from the
GPS navigation message, subframes 1 to 3. See IS-GPS-200 for a full description of the
contents of the Subframes.
• In SF1D0 to SF3D7, the parity bits have been removed, and the 24 bits of data are
located in Bits 0 to 23. Bits 24 to 31 shall be ignored.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x31

(8) or (104)

see below

CK_A CK_B

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Public Release

UBX Protocol
Page 123

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Format

0

U4

-

svid

-

4

U4

-

how

-

SV ID for which this ephemeris data is
(Valid Range: 1 .. 32).
Hand-Over Word of first Subframe. This is
required if data is sent to the receiver.
0 indicates that no Ephemeris Data is following.

-

sf1d
sf2d
sf3d

-

Subframe 1 Words 3..10 (SF1D0..SF1D7)
Subframe 2 Words 3..10 (SF2D0..SF2D7)
Subframe 3 Words 3..10 (SF3D0..SF3D7)

Start of optional block

8
40
72

U4[8]
U4[8]
U4[8]

End of optional block

AID-ALPSRV (0x0B 0x32)
ALP client requests AlmanacPlus data from server
Message

AID-ALPSRV

Description

ALP client requests AlmanacPlus data from server

Type

Output Message

Comment

This message is sent by the ALP client to the ALP server in order to request data. The given
identifier must be prepended to the requested data when submitting the data.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x32

16

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Identifier size. This data, beginning at message
start, must prepend the returned data.
Requested data type. Must be different from
0xff, otherwise this is not a data request.
Requested data offset [16bit words]
Requested data size [16bit words]
Unused when requesting data, filled in when
sending back the data
Actual data size. Unused when requesting data,
filled in when sending back the data.
Identifier data
Identifier data
Identifier data

Format

0

U1

-

idSize

bytes

1

U1

-

type

-

2
4
6

U2
U2
U2

-

ofs
size
fileId

-

8

U2

-

dataSize

bytes

10
11
12

U1
U1
U4

-

id1
id2
id3

-

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UBX Protocol
Page 124

ALP server sends AlmanacPlus data to client
Message

AID-ALPSRV

Description

ALP server sends AlmanacPlus data to client

Type

Input Message

Comment

This message is sent by the ALP server to the ALP client and is usually sent in response to a
data request. The server copies the identifier from the request and fills in the dataSize and
fileId fields.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x32

16 + 1*dataSize

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Format

0
1
2
4
6

U1
U1
U2
U2
U2

-

idSize
type
ofs
size
fileId

bytes
-

8

U2

-

dataSize

bytes

10
11
12

U1
U1
U4

-

id1
id2
id3

-

Identifier size
Requested data type
Requested data offset [16bit words]
Requested data size [16bit words]
Corresponding ALP file ID, must be filled in by
the server!
Actual data contained in this message, must be
filled in by the server!
Identifier data
Identifier data
Identifier data

data

-

Data for the ALP client

Start of repeated block (dataSize times)

16 + 1*N

U1

-

End of repeated block

ALP client sends AlmanacPlus data to server.
Message

AID-ALPSRV

Description

ALP client sends AlmanacPlus data to server.

Type

Output Message

Comment

This message is sent by the ALP client to the ALP server in order to submit updated data.
The server can either replace the current data at this position or ignore this new data
(which will result in degraded performance).

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x32

8 + 2*size

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

idSize
type
ofs
size

bytes
-

Identifier size
Set to 0xff to mark that is *not* a data request
Data offset [16bit words]
Data size [16bit words]

Format

0
1
2
4

U1
U1
U2
U2

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AID-ALPSRV continued
Byte Offset

Number

Scaling

Name

Unit

Description

-

fileId

-

Corresponding ALP file id

data

-

16bit word data to be submitted to the ALP
server

Format

6

U2

Start of repeated block (size times)

8 + 2*N

U2

-

End of repeated block

AID-ALP (0x0B 0x50)
ALP file data transfer to the receiver
Message

AID-ALP

Description

ALP file data transfer to the receiver

Type

Input message

Comment

This message is used to transfer a chunk of data from the AlmanacPlus file to the receiver.
Upon reception of this message, the receiver will write the payload data to its internal
non-volatile memory, eventually also erasing that part of the memory first. Make sure that
the payload size is even sized (i.e. always a multiple of 2). Do not use payloads larger than
~ 700 bytes, as this would exceed the receiver’s internal buffering capabilities. The receiver
will (not-) acknowledge this message using the message alternatives given below. The host
shall wait for an acknowledge message before sending the next chunk.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x50

0 + 2*Variable

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

alpData

-

ALP file data

Format
Start of repeated block (Variable times)

N*2

U2

-

End of repeated block

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Mark end of data transfer
Message

AID-ALP

Description

Mark end of data transfer

Type

Input message

Comment

This message is used to indicate that all chunks have been transferred, and normal receiver
operation can resume. Upon reception of this message, the receiver will verify all chunks
received so far, and enable AssistNow Offline and GPS receiver operation if successful. This
message could also be sent to cancel an incomplete download.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x50

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

dummy

-

Value is ignored

Format

0

U1

Acknowledges a data transfer
Message

AID-ALP

Description

Acknowledges a data transfer

Type

Output message

Comment

This message from the receiver acknowledges successful processing of a previously received
chunk of data with the “Chunk Transfer” Message. This message will also be sent once a
“Stop” message has been received, and the integrity of all chunks received so far has been
checked successfully.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x50

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

ack

-

Set to 0x01

Format

0

U1

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Indicate problems with a data transfer
Message

AID-ALP

Description

Indicate problems with a data transfer

Type

Output message

Comment

This message from the receiver indicates that an error has occurred while processing and
storing the data received with the “Chunk Transfer” message. This message will also be
sent once a stop command has been received, and the integrity of all chunks received
failed.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x50

1

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

-

nak

-

Set to 0x00

Format

0

U1

Poll the AlmanacPlus status
Message

AID-ALP

Description

Poll the AlmanacPlus status

Type

Periodic/Polled

Comment

-

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0B 0x50

24

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Prediction start time of week
Prediction duration from start of first data set to
end of last data set
Current age of ALP data
Prediction start week number
Truncated week number of reference almanac
Reserved for future use
Number of satellite data sets contained in the
ALP data
Reserved for future use
Reserved for future use
Reserved for future use

Format

0
4

U4
U4

-

predTow
predDur

s
s

8
12
14
16
20

I4
U2
U2
U4
U1

-

age
predWno
almWno
res1
svs

s
-

21
22
23

U1
U1
U1

-

res2
res3
res4

-

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TIM (0x0D)
Timing Messages: i.e. Timepulse Output, Timemark Results.
Messages in this class are output by the receiver, giving information on Timepulse and Timemark
measurements.

TIM-TP (0x0D 0x01)
Timepulse Timedata
Message

TIM-TP

Description

Timepulse Timedata

Type

Periodic/Polled

Comment

This message contains information for high precision timing. Note that contents are correct
only if the timepulse is set to one pulse per second.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0D 0x01

16

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

2^-32
-

towMS
towSubMS
qErr
week
flags
res

ms
ms
ps
weeks
-

Timepulse time of week according to time base
Submillisecond part of TOWMS
Quantization error of timepulse.
Timepulse week number according to time base
bitmask (see graphic below)
unused

Format

0
4
8
12
14
15

U4
U4
I4
U2
X1
U1

Bitfield flags
This Graphic explains the bits of flags

Name

Description

timeBase

0=Time base is GPS
1=Time base is UTC

utc

0=UTC not available
1=UTC available

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TIM-TM2 (0x0D 0x03)
Time mark data
Message

TIM-TM2

Description

Time mark data

Type

Periodic/Polled

Comment

This message contains information for high precision time stamping / pulse counting.
The delay figures given in CFG-TP are also applied to the time results output in this
message.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0D 0x03

28

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

marker channel 0 or 1
Bitmask (see graphic below)
edge counter.
week number of last rising edge
week number of last falling edge
tow of rising edge
millisecond fraction of tow of rising edge in
nanoseconds
tow of falling edge
millisecond fraction of tow of falling edge in
nanoseconds
Accuracy estimate

Format

0
1
2
4
6
8
12

U1
X1
U2
U2
U2
U4
U4

-

ch
flags
count
wnR
wnF
towMsR
towSubMsR

time
ms
ns

16
20

U4
U4

-

towMsF
towSubMsF

ms
ns

24

U4

-

accEst

ns

Bitfield flags
This Graphic explains the bits of flags

Name

Description

mode

0=single
1=running

run

0=armed
1=stopped

newFallingEdg
e

new falling edge detected

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Bitfield flags Description continued
Name

Description

timeBase

0=Time base is Receiver Time
1=Time base is GPS
2=Time base is UTC
0=UTC not available

utc

1=UTC available
0=Time is not valid

time

1=Time is valid (Valid GPS fix)

newRisingEdge

new rising edge detected

TIM-SVIN (0x0D 0x04)
Survey-in data
Message

TIM-SVIN

Description

Survey-in data

Type

Periodic/Polled

Comment

This message is only supported on timing receivers
This message contains information about survey-in parameters. For details about the Time
Mode see section Time Mode Configuration.

Message Structure

Header

ID

Length (Bytes)

Payload

Checksum

0xB5 0x62

0x0D 0x04

28

see below

CK_A CK_B

Payload Contents:
Byte Offset

Number

Scaling

Name

Unit

Description

Passed survey-in observation time
Current survey-in mean position ECEF X
coordinate
Current survey-in mean position ECEF Y
coordinate
Current survey-in mean position ECEF Z
coordinate
Current survey-in mean position 3D variance
Observations used during survey-in
Survey-in position validity flag
Survey-in in progress flag
Reserved

Format

0
4

U4
I4

-

dur
meanX

s
cm

8

I4

-

meanY

cm

12

I4

-

meanZ

cm

16
20
24
25
26

U4
U4
U1
U1
U2

-

meanV
obs
valid
active
reserved

mm^2
-

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
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Public Release

UBX Protocol
Page 131

Appendix
u-blox 5 Default Settings
The default settings listed in this section apply to u-blox 5 ROM-based receivers with ROM version 4.0. These
values assume that the default levels of the configuration pins have been left unchanged. Default settings are
dependent on the configuration pin settings, for information regarding these settings, consult the applicable
Data Sheet.

Antenna Supervisor Settings (UBX-CFG-ANT)
For parameter and protocol description see section UBX-CFG-ANT.
Antenna Settings
Parameter

Default Setting

Enable Control Signal
Enable Short Circuit Detection
Enable Short Circuit Power Down logic
Enable Automatic Short Circuit Recovery logic
Enable Open Circuit Detection

Enabled
Enabled
Enabled
Enabled
Disabled

Unit

Datum Settings (UBX-CFG-DAT)
For parameter and protocol description see section UBX-CFG-DAT.
Datum Default Settings
Parameter

Default Setting

Datum

0 – WGS84

Unit

Navigation Settings (UBX-CFG-NAV5)
For parameter and protocol description see section UBX-CFG-NAV5.
Navigation Default Settings
Parameter

Default Setting

Unit

Dynamic Platform Model
Fix Mode
Fixed Altitude
Fixed Altitude Variance
Min SV Elevation
DR Timeout
PDOP Mask
TDOP Mask
P Accuracy
T Accuracy
Static Hold Threshold

0 – Portable
Auto 2D/3D
N/A
N/A
5
0
25
25
100
300
0.00

#
m
m^2
deg
s
m
m
m/s

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Appendix
Page 132

Output Rates (UBX-CFG-RATE)
For parameter and protocol description see section UBX-CFG-RATE.
Output Rate Default Settings
Parameter

Default Setting

Unit

Time Source
Measurement Period
Measurement Rate

1 – GPS time
1000
1

ms
Cycles

SBAS Configuration (UBX-CFG-SBAS)
For parameter and protocol description see section UBX-CFG-SBAS.
SBAS Configuration Default Settings
Parameter

SBAS Subsystem
Allow test mode usage
Ranging (Use SBAS for navigation)
Apply SBAS Correction Data
Apply integrity information
Number of search channels
PRN Codes

Default Setting

Unit

Enabled
Disabled
Enabled
Enabled
Disabled
3
120, 122, 124, 126-127, 129, 131, 134-135, 137-138

Port Setting (UBX-CFG-PRT)
For parameter and protocol description see section UBX-CFG-PRT.
Port Default Settings
Parameter

DDC/I2C (Target0)
Protocol in
Protocol out
USART1 (Target1)
Protocol in
Protocol out
Baudrate
USART2 (Target2)
Protocol in
Protocol out
Baudrate
USB (Target3)
Protocol in
Protocol out
SPI (Target4)
Protocol in
Protocol out

Default Setting

Unit

0+1 – UBX+NMEA
0+1 – UBX+NMEA
0+1 – UBX+NMEA
0+1 – UBX+NMEA
9600

baud

None
None
9600

baud

0+1 – UBX+NMEA
0+1 – UBX+NMEA
0+1 – UBX+NMEA
0+1 – UBX+NMEA

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Appendix
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Port Setting (UBX-CFG-USB)
For parameter and protocol description see section UBX-CFG-USB.
USB default settings
Parameter

Default Setting

Unit

Power Mode
Power Mode
Bus Current required

Bus powered
120

mA

Message Settings (UBX-CFG-MSG)
For parameter and protocol description see section UBX-CFG-MSG.
Enabled output messages
Message

Type

All Targets

NMEA - GGA
NMEA - GLL
NMEA - GSA
NMEA - GSV
NMEA - RMC
NMEA - VTG

Out
Out
Out
Out
Out
Out

1
1
1
1
1
1

NMEA Protocol Settings (UBX-CFG-NMEA)
For parameter and protocol description see section UBX-CFG-NMEA.
NMEA Protocol Default Settings
Parameter

Default Setting

Enable position output even for invalid fixes
Enable position even for masked fixes
Enable time output even for invalid times
Enable time output even for invalid dates
Version
Compatibility Mode
Consideration Mode
Number of SV

Unit

Disabled
Disabled
Disabled
Disabled
2.3
Disabled
Enabled
Unlimited

INF Messages Settings (UBX–CFG–INF)
For parameter and protocol description see section UBX-CFG-INF.
NMEA default enabled INF msg
Message

Type

All Targets

INF-Error
INF-Warning
INF-Notice
INF-Test

Out
Out
Out
Out

1
1
1

Range/Remark

In NMEA Protocol only (GPTXT)
In NMEA Protocol only (GPTXT)
In NMEA Protocol only (GPTXT)

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Appendix
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NMEA default enabled INF msg continued
Message

Type

INF-Debug
INF-User

Out
Out

All Targets

1

Range/Remark

In NMEA Protocol only (GPTXT)

Timepulse Settings (UBX–CFG–TP)
For parameter and protocol description see section UBX-CFG-TP.
Timepulse default settings
Parameter

Pulse Mode
Pulse Period
Pulse Length
Time Source
Cable Delay
User Delay
SyncMode

Default Setting

+1 – rising
1000
100
1 – GPS time
50
0
0 (no time pulse in case of no fix)

NMEA, UBX Protocol Specification, u-blox 5 GNSS Receiver
GPS.G5-X-07036-D
Public Release

Unit

ms
ms
ns
ns

Appendix
Page 135



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