CANBERRA RS-915 GPS-COM SUPERVISOR/REPEATER User Manual III

CANBERRA GPS-COM SUPERVISOR/REPEATER Users Manual III

Contents

Users Manual III

This document describes how works the 915MHz RF part of the Repeater/Supervisor system in order to
show conformity to part 15-247 of the FCC rules.
The following items are detailed:
- System description
- Timing
Le Val d'Ombrée - 49520 COMBREE
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D
ESIGNATION DU PROJET
:
CANBERRA04
Référence du document :
CAN04_08301_A (Repeater supervisor
915MHz RF System
description).doc
Evolutions
Indice Date Nature des évolutions Opérateur
A 23/07/2008 Création C. QUENTEL
B 30/07/2008 Clarify §3.2 C. QUENTEL
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CONTENTS
1.
OUTPUT POWER AND CHANNEL SEPARATION OF A RADIOFREQUENCY DEVICE..................3
2.
FREQUENCY RANGE OF A RADIOFREQUENCY DEVICE...................................................................3
3.
SYSTEM DESCRIPTION.................................................................................................................................3
4.
RECEIVER INPUT BANDWITH....................................................................................................................5
5.
SYSTEM RECEIVER HOPPING CAPABILITY..........................................................................................6
6.
DWELL TIME...................................................................................................................................................6
7.
EQUAL HOPPING FREQUENCY USE.........................................................................................................6
8.
CHANNEL SEPARATION...............................................................................................................................6
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1. OUTPUT POWER AND CHANNEL SEPARATION OF A
RADIOFREQUENCY DEVICE
The operating mode doesn’t influence the ouput power and the chanel spacing. There is
only one transmitter which is driven by identical input parameters concerning these two
parameters.
Channels spacing: 500 kHz
Output power (max): 500mW
A pseudo randomly ordered list of hopping frequencies (50 channels) is defined:
1, 15, 17, 4, 10, 6, 2, 11, 13, 18, 7, 12, 3, 9, 14, 5, 8, 16, 19,
20, 24, 37, 32, 30, 36, 21, 25, 31, 34, 22, 27, 35, 28, 26, 23,
33, 29, 38, 39, 43, 46, 42, 40, 47, 41, 45, 49, 50, 48, 44
2. FREQUENCY RANGE OF A RADIOFREQUENCY DEVICE
Hereby we declare that the maximum frequency of this device is:
902,75 MHz - 927,25 MHz
This is according the Core Specification (+ critical errata) for devices which will be
operated in the USA.
This was checked during the Qualification tests.
Other frequency ranges (e.g. for Spain, France, Japan) which are allowed according the
Core Specification are not supported by this device.
3. SYSTEM DESCRIPTION
The Repeater/Supervisor has two different and functioning modes:
- Supervisor mode connected to a PC through a wired serial link
- Supervisor mode connected to a PC through a radio frequency link
3.1. SUPERVISOR MODE CONNECTED TO A PC THROUGH A WIRED
SERIAL LINK
The system consists of a master with one or more slave (1 to 200 slaves).
The master name is “Repeater/Supervisor”.
There are two types of slave devices, named “GPS-COM” or “CSP-COM”
The function of the Repeater/Supervisor device (master) is to communicate with slave
devices (GPS-COM or CSP-COM) to exchange data synchronously through a radio
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frequency link and to send data received from the slave to the PC through the wired serial
link.
When the Repeater/Supervisor device is powered on it is set on the idle state (no RX, no
TX).
When the Repeater/Supervisor device receives a start command (from its wired serial link)
sent by user, it starts sends a packet of synchronisation data on all channels according to the
hopping frequencies table in order to synchronize the slaves.
It is important to notice that the time between master power on and reception of a start
command is a random time and is not predictable.
When a slave receives synchronisation data from Repeater/Supervisor, it jumps
synchronously with the master on the following channel according to the hopping
frequencies table. It is synchronized with the Repeater/Supervisor.
When synchronized, Repeater/Supervisor and slaves can exchange data.
Repeater/Supervisor continues to send synchronisation data.
When Repeater/Supervisor receives data from a slave it transmits this data to the PC
through the wired serial link.
The system stays on a channel during 165ms (time slot). This time slot consists on three
parts: 1. Calibration channel (no TX, no RX)
2. Repeater/Supervisor data (including synchronisation data) transmission,
slaves are in reception state (no TX). Only one frame is sent by the
Repeater/Supervisor during this period.
3. Slave data transmission (only one slave is transmitting during a time slot),
Repeater/Supervisor is in reception state (no TX). Only one frame is sent by
the slave during this period.
Timing: 1- Calibration: 45ms
2- Repeater/Supervisor transmission: 60ms (dwell time = 17,3ms max.)
3- Slave transmission: 60ms
Time slot: 165ms
Co-ordination of the hopping sequence to avoid simulateous occupancy by multiple
transmitters:
When synchronised with the Repeater/Supervisor, each slave has a specific number (1 to
200). That allows each slave to sent data during a specific time slot depending on this
number.
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3.2. SUPERVISOR MODE CONNECTED TO A PC THROUGH A RADIO
FREQUENCY LINK
This mode is identical to the previous mode, with the difference that a second RF module
is used to transmit data to the PC on a radio frequency link instead of the wired serial link.
The second RF module is synchronised with the first RF module that is used to
communicate with slaves GPS-COM or CSP-COM. The two RF modules jump
synchronously on the following channel according to the same hopping frequencies table
but with a fixed offset (15 > offset > 5).
This prevents the two RF modules to transmit data at the same time on the same channel.
The system stays on a channel during 165ms (time slot). This time slot consists on three
parts: 1. Calibration channel (no TX, no RX)
2. Repeater/Supervisor data transmission to the slave through first RF module on
channel X. Repeater/Supervisor data transmission to the PC through second
RF module on channel Y (X≠Y).Transmissions on channel X and Y occurs
in parallel. Only one frame is sent by the Repeater/supervisor on channel X
during this period and only one frame is sent in parallel by the
Repeater/supervisor on channel Y during this period
4. Slave data transmission (only one slave is transmitting during a time slot),
Repeater/Supervisor is in reception state (no TX). Only one frame is sent by
the slave during this period.
Timing: 1- Calibration: 45ms
2- Repeater/Supervisor transmission on each channel: 60ms (dwell time =
17,3ms max.)
3- Slave transmission: 60ms
Time slot: 165ms
4. RECEIVER INPUT BANDWITH
The input bandwidth of the receiver is 40 kHz.
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5. SYSTEM RECEIVER HOPPING CAPABILITY
There is only one hopping sequence. The Repeater/Supervisor and the slave
follow this sequence. Both devices shift between Rx and Tx time slot according to
the clock of the Repeater/Supervisor.
There isn’t repeating of a packet. Data are sent independently of the frequency.
6. DWELL TIME
Repeater/Supervisor dwell time = 17,3ms max each 165ms.
7. EQUAL HOPPING FREQUENCY USE
During each time slot, Repeater/Supervisor is sending only frames. Next
transmission event starts on the next time slot.
8. CHANNEL SEPARATION
The nominal channel spacing of the device is 500 kHz.
This was checked during the Qualification tests.

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