SEA COM SEA157S VHF Marine Radiotelephone/Class A DSC GMDSS User Manual April 5 2000 FIRST DRAFT

SEA COM CORPORATION VHF Marine Radiotelephone/Class A DSC GMDSS April 5 2000 FIRST DRAFT

Maintenance/Service manual

SEA COM CORPORATION.
PRELIMINARY MAINTENANCE MANUAL
VHF FM RADIOTELEPHONE & DSC CONTROLLER
MODEL SEA 157S
© Copyright 2010
SEA COM Corp.
All rights reserved.
SEA COM Corp.
7030 220th St. SW
Mountlake Terrace, Washington 98043
TEL: (425) 771-2182
FAX: (425) 771-2650
101
019A
**IMPORTANT**
NOTICE TO INSTALLERS
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NOTE: The safe compass distance for this equipment (As defined in
Paragraph 29 of IEC Publication 92-101, Third Edition):
SEA 157S VHF FM TRANSCEIVER/DSC CONTROLLER = 2.0 meters
------------------------------------------------------------------
TABLE OF CONTENTS
PAGE
1. INTRODUCTION............................................1-1
2. SEA 157S SPECIFICATIONS.................................2-1
2.1 General............................................2-1
2.2 Transmitter........................................2-1
2.3 Receiver...........................................2-2
2.4 Mechanical.........................................2-2
2.5 DSC controller.....................................2-3
3. OPERATING THE SEA 157S..................................3-1
3.1 Front Panel Controls...............................3-1
3.2 Display............................................3-1
3.3 Push To Talk.......................................3-1
3.4 Radiotelephone Operating System Functions..........3-2
3.5 Digital Selective Calling Operating System.........3-7
3.6 Using Test, Calibration and Diagnostic Utilities...3-13
3.7 USA Frequency List.................................3-14
3.8 International Channel list.........................3-15
3.9 Weather Channel list...............................3-16
4. INSTALLATION............................................4-1
4.1 Preliminary Check..................................4-1
4.2 Shelf or Overhead Mounting.........................4-1
4.3 Bulkhead Mounting..................................4-1
4.4 Power Supply Wiring................................4-1
4.5 Antenna Wiring.....................................4-1
4.6 External Speaker Wiring............................4-2
4-7 NMEA 0183 and RS232 Wiring.........................4-2
5. THEORY OF OPERATION.....................................5-1
5.1 Frequency Synthesizer..............................5-1
5.2 Modulation Circuit.................................5-2
5.3 Main Receiver......................................5-2
5.4 Transmit Amplifier Chain...........................5-5
5.5 Antenna Interface Circuits.........................5-5
5.6 Automatic RF Power Control (APC) and TX Logic......5-6
5.7 TX Logic Detector..................................5-6
5.8 Power and Audio Circuits...........................5-6
5.9 Microcomputer Circuitry............................5-7
5.10 Keypad/Keypad Lighting.............................5-8
5.11 Display/Display Lighting...........................5-8
6. MAINTENANCE.............................................6-1
6.1 General............................................6-1
6.2 Recommended Test Equipment.........................6-1
6.3 Basic Performance Tests............................6-2
6.4 Transmitter Alignment..............................6-3
6.5 Receiver alignment.................................6-6
7. Block Diagram/Schematics............................7-1/7-9
LIST OF FIGURES
FIG. ___________________DESCRIPTION___________________ Page
2.1 Front view of SEA 157S.............................2-4
2.2 Rear view of SEA 157S..............................2-5
4.1 Outline Dimensions of SEA 157S.....................4-3
4.2 Flush Mount Kit Drill Template for SEA 157S........4-4
6.1 Transmitter test setup.............................6-7
6.2 Receiver test setup................................6-8
7.1 Functional Block Diagram...........................7-1
7.2.1 RF Mainboard Schematic Diagram, Sheet 1............7-2
7.2.2 RF Mainboard Schematic Diagram, Sheet 2............7-2
7.2.3 RF Mainboard Schematic Diagram, Sheet 3............7-4
7.2.4 RF Mainboard Schematic Diagram, Sheet 4............7-5
7.2.5 RF Mainboard Schematic Diagram, Sheet 5............7-6
7.3 VCO Board Schematic Diagram........................7-7
7.4 Receiver Board Schematic Diagram...................7-7
7.5.1 CPU Mezzanine Board Schematic Diagram, Sheet 1.....7-8
7.5.2 DSP Mezzanine Board Schematic Diagram, Sheet 2.....7-8
7.6 Channel 70 Circuit Board Schematic Diagram.........7-9
1 INTRODUCTION
This SEA 157S Service Manual provides detailed technical
information for use by installation and service technicians.
General operating instructions and installation drill
templates are provided in the SEA 157S Operator's Handbook
(SEA P/N OPR-157S) supplied with each SEA 157S.
SEA COM Corp. continually strives to improve its products so
that we may better serve our customers. SEA COM reserves the
right to make changes to SEA 157S specifications, hardware,
software or documentation at any time without notice.
SEA COM's Marine Service Department is always available to
provide additional help with technical difficulties.
Please call SEA COM's Service Department to obtain a Return
Authorization Number (RA#) before shipping equipment to SEA
COM.
Service parts are available through SEA COM Marine
Sales/Service Departments. Please order parts using SEA part
numbers found in Section 8.
1-1
2 SEA 157S SPECIFICATIONS:
2.1 GENERAL
FREQUENCY RANGE: TX 155-159MHz
US TX 156.0-157.5MHz
RX 155-164MHz
FREQUENCY RESOLUTION: 12.5kHz
CHANNELS: All US, Canadian, Int'l
plus 10 WX
POWER REQUIREMENT: Voltage: 13.6Vdc, +/-15%
Negative Ground
CURRENT: Max TX: 5.5 Amps (25W)
1.0 Amps (1W)
RX (STBY): 0.4 Amps
RX (Max): 1.0 Amps
FUSES: 7.5 Amps (External)
2.2 TRANSMITTER
EMISSION: 16K0F3E & 11K2F3E (Voice)
13K5G2D (DSC)
11K2F2D (GMSK)
POWER OUTPUT: 25W, 1W into 50 ohms
SPURIOUS EMISSIONS: -80 dB or better
SPURIOUS RADIATION: Complies with FCC 80.211(f)
AUDIO HARMONIC DISTORTION: 10% max.
AUDIO FREQUENCY RESPONSE: +1,-3dB of +6 dB/octave
Pre-emphasis 300-3000 Hz
HUM AND NOISE: 50 dB
FREQUENCY DEVIATION: 5kHz max. peak
CARRIER FREQUENCY STABILITY: ±5ppm, -30 to +60 C
TRANSMITTER ATTACK TIME: < 100 milliseconds
2-1
2.3 RECEIVER
FREQUENCY RANGE: Simplex 155-159MHz
Semi-duplex 159-164MHz
INTERMEDIATE FREQUENCIES: 21.4MHz, 450kHz
SENSITIVITY: <0.3uV for 12 dB SINAD
AUDIO FREQUENCY RESPONSE: Within +1,-3 dB of 6 dB per
octave de-emphasis from 300-
3000Hz
AUDIO OUTPUT: 4W at less than 10%
distortion into external
4 ohm load. 2W internal
HUM AND NOISE: Unsquelched: -45dB
Squelched: -55dB
ADJACENT CHANNEL SELECTIVITY: -80dB @ 25kHz
-85dB @ >50kHz
SPURIOUS EMISSION, RADIATION: Complies with FCC
SQUELCH SENSITIVITY: Threshold: .2uV max.
Tight: max 10dB above
reference sensitivity
RECEIVER ATTACK TIME: Less than 100mSec
RECEIVER CLOSING TIME: 100msec typical
250mSec max
SCAN RATE: Max 10 channels/second
MODULATION ACCEPTANCE: 6kHz minimum
7kHz typical
2.4 MECHANICAL
DIMENSIONS: (HEIGHT-WIDTH-DEPTH)
In: 3.6 x 9.6 x 3.1
mm: 91 x 244 x 79
WEIGHT: Lbs: 3.0
Kgs: 1.4
2-2
2.5 SEA 157S VHF DIGITAL SELECTIVE CALLING CONTROLLER
The VHF Digital Selective Calling Controller
incorporated into the SEA 157S VHF Radiotelephone has
been designed to comply with all FCC regulations given
in 47 CFR 80.225. This encompasses compliance with the
following documents, which are included for reference:
80.225(a) ITU-R Recommendation M.493-9 Class D
80.225(a) RTCM Paper 56-95/SC101-STD
2-3
Page 2-4
SEA 157S
Front View
Figure 2.1
Page 2-5 Figure 2.2
SEA 157S
Rear View
3. OPERATING THE SEA 157S
3.1 FRONT PANEL CONTROLS
Figure 2.1 illustrates the front panel of the SEA 157S. The
functions of the individual controls and indicators are listed
below.
3.1.1 ROTARY CONTROL
The rotary control of the SEA 157S is used for several radio
functions. It can be used to adjust the channel, volume, squelch
and backlighting from the normal radio operating mode. In menu
mode it is used to select from a list of menu options and is used
to adjust the selected function.
The user can set the default mode for the rotary control using the
setup menu. The rotary control will return to the default state 5
seconds (user selectable) after the last adjustment is made.
Squelch mode adds 5 seconds to this timeout to allow for squelch
on/off time while adjusting the level.
3.1.2 KEYPAD
A 15 key back-lighted keypad is provided which, together with the
LCD graphics display, provides an operating system which permits
the operator to control both the radiotelephone and digital
selective calling (DSC) features of the SEA 157S.
3.1.3 PWR Key
Press and hold the PWR key for 3 seconds then release to turn the
radio on. The display will light, indicating the radio is powered.
To turn the radio off, press and hold the PWR key for 3 seconds
then release. The display will turn off, indicating that the radio
is powering down to the off condition.
3.2 DISPLAY
The SEA 157S uses a 128 X 64 graphics LCD display. The display is
back-lighted and operates interactively with the keypad to provide
an effective operator interface to the radiotelephone/DSC
functions of the SEA 157S.
3.3 PUSH TO TALK
The radio is put into transmit mode by pressing the microphone
push to talk key. It remains in transmit mode until the push to
talk switch is released or until an internal 5 minute timer
expires. A TX annunciator is displayed during transmit.
Note: The internal DSC controller can also initiate transmissions
independent of the push to talk switch on the microphone.
3-1
3.4 RADIOTELEPHONE OPERATING SYSTEM FUNCTIONS
3.4.1 CHANNEL SELECTION
The rotary control is used to select the channels. Push the ENT
key until “Change Channel” is seen on the middle right side of the
display, then use the rotary control to select the desired
channel. This operates within the current channel list and wraps
around at both ends of the list. eg. from channel 88A to channel 1
when moving up through the list.
The display shows the channel name below the channel number. The
rotary control reverts to volume after 10 seconds of no activity.
The numerical keys can also be used to select a channel directly.
The radio supports the standard 2 digit VHF channel list. To enter
a channel press the channel number with leading zero digits to
switch to the channel immediately. If a single digit is pressed
and you delay for 10 seconds the radio will switch to that single
digit channel. For example, to go to channel 23 press 2,3 to
switch to the channel immediately. Press 0,5 to go to channel 5
immediately. Press 6 and pause for 10 seconds and the radio will
switch to channel 6.
In the Weather list the operation is similar to this, if the 2
through 9 keys are pressed in WX mode the channel is selected
immediately, because there are only 10 weather channels available.
If 0 is pressed then the channel number from 1 to 9 is waited for
with the first digit blinking. If 1 is pressed it waits for the 0
if you want to go to channel 10 or times out after 10 seconds and
goes to channel 1.
3.4.2 VOLUME CONTROL
The rotary control is used for this function. The default mode is
volume. Rotate the control to set the desired volume level. The
display will show “Change VOL XX” on the middle right side, “XX”
is the current volume level (0 to 15).
3.4.3 SQUELCH CONTROL
Push the ENT key until display shows “Change SQL XX” on the middle
right side, “XX” is the current squelch setting (0 to 15), then
use the rotary control to adjust the squelch level as desired. The
squelch is returned to the user selected state 10 seconds after
the last adjustment.
Pressing FUNC-9 will toggle the squelch on and off, as indicated
by SQL in the upper right corner of the display.
3-2
3.4.4 ADJUSTING THE BACKLIGHTING LEVEL
Push the FUNC key until display shows “Change DIM XX” on middle
right side of display. “XX” is the current brightness setting. 0
is off and 15 is maximum. Using the rotary control, adjust the
brightness level as desired. The rotary control is returned to the
user selected state 10 seconds after the last adjustment.
3.4.5 CHANNEL LIST SELECTION
Pressing FUNC-6 will toggle the radio between the USA, INT and WX
channel lists. The radio will go to the last used channel in the
selected list.
3.4.6 EMERGENCY CHANNEL SELECTION
Pushing the 16# key at any time, in any state of operation, will
cause the radio to go to CH16 in the current frequency list, or in
the case of pressing 16# key while in the Weather list, it will go
to CH16 in the USA list.
3.4.7 TRANSMITTER POWER CONTROL
On channels that allow 25W transmission, pressing FUNC-7 toggles
the transmitter power level between 25W and 1W. FUNC-7 is non-
functional on channels that only allow 1W. When transmitting on a
1W only channel, the FUNC key may be held down while transmitting
to temporarily switch to 25W. 1W will be displayed when in the 1W
mode and 25W when in the 25W mode.
3.4.8 DUAL WATCH
The SEA 157S has two watch modes available. Dual watch is
initiated by pressing FUNC-1 briefly while on the primary channel
you want to monitor. DW will be indicated on the display and
channel 16 will be checked every 2 seconds while there is no
activity on either channel. If there is activity on the primary
channel or on channel 16, the radio will remain on that channel
until there is no activity for a pre-programmed number of seconds
[hangtime]. This behavior can be changed so that channel 16 always
has priority by using the Dual Watch setup menu option.
The display will indicate which channel is operational. Pressing
PTT will exit dual watch and switch to the current channel.
Dual Watch will not be initiated if selected while on channel 16.
The Triple Watch function is started by pressing FUNC-1 for longer
than 1 second on the primary channel that you want to monitor. TW
will be indicated on the display and will check channel 16 and the
Priority channel every 2 seconds. By default channel 16 has
priority, but this behavior can be changed using the Triple Watch
setup menu option.
3-3
3.4.9 SEEK
The Seek mode scans all channels in the selected list (USA/INT/WX)
and is started by pressing FUNC-3. The display will show SCN and
the radio will scan all the channels in the current list.
3.4.10 SCAN
The Scan function is initiated by briefly pressing the FUNC-2. The
display will show SCN and the radio will scan the channels that
are members of the Scan List (indicated by the MEM flag). The
channels will be scanned and hold on an open channel for the user
selectable hangtime after the channel becomes inactive. Channel 16
is always included in the scan list regardless of the MEM list
state. Only the memorized channels in the current list will be
scanned.
3.4.11 PRIORITY SCAN
If the priority channel is selected BEFORE entering the scan mode,
the receiver scans the priority channel in between each channel.
3.4.12 SCAN CHANNEL PROGRAMMING
Press and hold the ENT key to bring up the Channel Operation menu.
Select “Add to Scan List” function to tag current channel. If the
selected channel is already in the list, menu selection reads “Del
from Scan List”. Pressing the ENT key adds or removes the current
channel from the scan list. The MEM flag will be on if the current
channel is included in the scan list. The memorized channels can
be scanned by using the MODE-2 scan function.
3.4.13 PRIORITY CHANNEL PROGRAMMING
Pressing FUNC-4 switches the radio to the programmed priority
calling channel. Press and hold the ENT key to bring up the
Channel Operation menu. Select “Make PRI Channel” to set the
currently selected channel to the priority channel. The factory
default for the PRI channel is channel 9, in the USA channel list.
The priority channel is also used by the Triple Watch mode and the
Priority scan and seek modes.
3.4.14 CONFIGURATION MENU
The Configuration Menu contains general option selections and
radio functions. Pressing FUNC-0 enters this menu. While in the
Configuration Menu, if there is no activity for 30 seconds, or if
the 16# or DIST keys are pressed, the menu will be exited with no
changes being saved, and the radio will return to the primary
radio display.
3-4
The rotary control is used to scroll through the list of menu
options. If a particular configuration needs to be changed, press
the ENT key to open the edit page. Some edit pages contain more
than one configurable option with the cursor pointing to the edit
field. Use the rotary control to select the item that needs to
change and press the ENT key to begin editing. While the option is
being adjusted it will blink. Some edits use the rotary control to
select from a predefined list of configurations while others use
the keyboard to enter the data. Modify the configuration
accordingly then press the ENT key to accept the change. While in
the Configuration Menu, pressing the FUNC key will abort the edit.
If no edit is open the radio will back up one menu level.
3.4.14.1 Watch Mode Operations
This Configuration page has the options for Channel Watch
operations.
Dual Wat
n Stops on the first active channel.
ch Options
All Cha
Chan 16 Channel 16 has priority and is checked every 2
seconds regardless of activity on other channels.
Triple W
All Chan Stops on the first active channel.
atch Options
Chan 16 Channel 16 has priority and is checked every 2
seconds regardless of activity on the Primary or
the Priority Channel.
PRI Chan The Priority Channel has priority and is checked
every 2 seconds regardless of activity on CH16 or
the Primary Channel.
3.4.14.2 DSC Options
This Configuration page contains options for DSC operation.
Auto Unable Automatic Reply, Unable to Comply
The radio will automatically send an Unable to
Comply response and stay on the current working
channel.
Auto Able Automatic Reply, Able to Comply
The radio will send an Able to Comply message and
will switch to the channel selected by the calling
station.
Manual + Timeout, Unable to Comply Manual Time
The radio will wait 4.5 minutes for the user to
manually send an Able to Comply message; otherwise
it will send an Unable to Comply message and stay
on the current working channel.
Manual Only Manual Reply only
The radio stays on the current working channel and
waits for the used to select the reply to send.
3-5
3.4.14.3 Radio Controls
This Configuration page contains a number of general radio
operation options.
Beep Level Use the rotary control to select the beep volume
level, 0-16. The radio will emit a short beep for
every turn of the rotary control.
Scan Hang Time Use the rotary control to select the amount of time
the radio in Scan remains on a channel after the
squelch closes, in 0.5 second increments, from 0 to
20 on the display (0 to 10 seconds).
Weather Alert Use the rotary control to select the Weather Alert
mode. When on a WX channel and a Weather Alert tone
is detected the radio will beep and stop scanning.
The display shows OFF and ON.
Rotary Control Timeout
Use the rotary control to select the amount of
time, in 0.5 second increments, to pause after the
rotary control has been used for an alternative
function before returning to the default mode
selected above. Allows selection of 0-59 (0 to 30
seconds).
3.4.14.4 Scrambl
Use the rotary control to select the scrambler
code, from 0 to 9, to use in the Scrambler mode.
Selecting 0 turns off the Scrambler.
e Options
3.4.14.5 Channel
When this function is selected the first digit of
the channel name will begin to flash. Use the
keyboard keys to enter a new character, or the
rotary control to move through the channel name.
Pressing the 16# key will abort the editing and
return to Channel 16 or Channel 9.
Name
3.4.14.6 DSC Call Lists
Selecting this option allows selection of one of the following
four supported DSC ID lists: DSC ID, Group, Phone Number and Coast
Stations. Use the rotary control to select a list to modify, then
Press ENT to open the List Display.
If a list contains entries, the names will be displayed in
alphabetical order. The rotary control may be used to scroll
through the list. Press ENT to view the complete entry. The List
View page contains the following three selections:
3-6
Add New Selecting Add New will open a blank entry page
where a Name and Number may be added. The Name may
be up to 15 characters long. The DSC ID field is 9
digits. The Phone Number may be up to 18 digits.
Edit Selecting Edit will allow the current entry to be
modified. Use the rotary control to move the cursor
and the keyboard to enter new information. When the
edit is complete, press ENT to save the entry into
the list and return to the List Display.
Delete An entry may be removed from the list with this
option.
3.4.14.7 Factory Reset
The Factory Reset option is used to return all
configuration parameters to their factory default
condition. A confirmation is required to perform
the reset. Selecting NO will abort the action and
return to the Configuration Menu.
3.4.14.8 Set DSC ID
Selecting this menu item will display the radio’s
current DSC ID. Press ENT key to open the edit
mode, then use the keypad keys to modify the ID.
Press ENT to save the changes. Press the FUNC key
to return to the Configuration Menu. Pressing 16#
or DIST key will exit immediately without saving
. any changes
NOTE: The DSC ID may be changed only twice after
factory initialization.
3.5 DIGITAL SELECTIVE CALLING OPERATING SYSTEM
3.5.1 TRANSMITTING A DISTRESS CALL
A distress DSC call may be initiated using the following
procedure:
1) Press either the local DIST key or the remote DIST key. An
alert tone will sound while the key is held.
2) Select from the list of available distress conditions shown.
If the radio is not supplied with positioning information from a
GPS or other device, you will be prompted to enter the Lat/Long
position. You may skip this step in an emergency and go back later
to enter the position. To manually enter the position, use the
keypad to input the digits and the rotary control to move the
cursor.
3-7
After selecting the distress condition and manually entering the
position, press and hold the distress key for 5 seconds to send
the distress call.
The radio will wait for an acknowledgment from the coast station
and automatically resend the DSC message approximately every 4
minutes if a coast station does not respond. During this time the
display will show the time until next transmission and the
“WAITING FOR ACK” status. At any time you may press the ENT key
to resend the distress call immediately.
NOTE: All DSC functions are disabled unless a valid DSC ID (MMSI
number) is programmed in the unit. See “Set DSC ID”, 3.4.14.8.
3
.5.2 TRANSMITTING A DSC CALL
To access the DSC Calling functions, press FUNC-8. This will bring
up the primary DSC menu. The menu selections are used for
reviewing received calls, programming station IDs and transmitting
the various DSC message formats.
Most calls will conform to one of the five predefined formats
which have a simplified calling procedure: Routine Individual
calls, Alternate Channel proposal, Distress Relay calls and All
Ship calls for the purpose of warning. For all other calls that do
not fit one of these predefined categories, the operator may
compose a call using the Build Class A operation. Class A formats
allow all call types to be generated, including geographic area
calls, group calls, non-voice (fax and data) calls, position
request and polls.
The 16# key may be used to abort the DSC call at any point in the
process and return to the Primary Radio Display.
When a DSC call is made that does not require the receiving
station to send an acknowledgment, such as an “ALL SHIP” call, the
radio switches to the selected voice communications channel
immediately after the call is sent. When an Individual call is
sent the unit will wait for an acknowledgement to be received
before switching to the selected channel.
While waiting for an acknowledgement to a DSC call the radio will
alternately display “DSC CALLING” and “WAITING FOR ACK”. The call
may be resent immediately by pressing the ENT key.
Once an acknowledgement is received the radio will switch to the
selected voice channel and the display will show “ABLE” or
“UNABLE”, depending on the response received, until the user takes
action such as keying the radio or changing channels.
3-8
3
.5.3 INDIVIDUAL DSC CALL
A routine Individual DSC Call is used to address another station
and propose a working voice channel. This type of call requires
the receiving station to send a response.
Start by selecting the desired working channel you want to use.
Press FUNC-8 to access the DSC Menu. Using the rotary control to
move the cursor, select Selective Call menu item, then press ENT.
The DSC Calling list will be displayed with the last station
called selected. Use the rotary control to select the desired
station. Press ENT to initiate the DSC call.
3
.5.4 GROUP DSC CALL
A routine Group Call is used to address a group of stations and
propose a working voice channel. This type of call requires no
response from the receiving stations.
Start by selecting the desired working channel you want to use.
Press FUNC-8 to access the DSC Menu. Using the rotary control to
move the cursor, select Group Call menu item, then press ENT. The
Group Calling list will be displayed with the last station called
selected. Use the rotary control to select the desired station.
Press ENT to initiate the DSC call.
3
.5.5 PLACING A TELEPHONE CALL WITH DSC
The DSC call system may be used to set up a telephone call through
n appropriately equipped coast station. a
To initiate a phone call, press FNC-8 to access the DSC Menu.
Using the rotary control to move the cursor, select the DSC Phone
Call menu item, then press ENT. The most recently contacted coast
station’s DSC ID and phone number will be displayed. If this
information is correct, press ENT to initiate the call.
To change the coast station’s DSC ID, use the rotary control to
move the cursor to the DSC ID field and then press ENT. Select
either “Direct Entry” or select the DSC ID from the predefined
Coast Station DSC ID list. Enter a new DSC ID if required. Press
ENT to complete the entry.
To change the telephone calling number, use the rotary control to
move the cursor to the phone number field, then press ENT. Select
either “Direct Entry” or select a phone number from the predefined
phone number list. Enter the new phone number if required. Press
ENT to complete the entry.
Press the ENT key to transmit the request to the coast station. If
the coast station is able to accept the request, the radio will
change to the working channel assigned by the coast station.
3-9
3.5.6 RECEIVING A DSC CALL
The SEA 157S constantly monitors CH70 using a dedicated watch
receiver. When a DSC call is received, the radio will beep quickly
2 times every 5 seconds. This alert tone will continue for 2
minutes or until the user presses a keypad key or the PTT switch,
at which time the alert tone will cease. The display will indicate
the type of call received, the source of the call (either the name
or DSC ID) and any other information that is relevant to the type
of call.
When a Distress Call is received the radio will sound an
alternating 2-tone distress alarm. The alert tone will continue
for 2 minutes or until the user presses a keypad key or the PTT
switch, at which time the alert tone will cease. The display will
indicate that a distress call has been received.
When an All Ships or Geographic Call is received the radio will
beep once and switch to the voice channel specified by the calling
station. The display will show “ALL SHIP” or “GEO CALL” while on
the selected channel. The display will revert to its normal
operating mode when the channel selector is changed or a key is
pressed.
When an Individual Call is received additional action may be taken
automatically, depending on the setting of the DSC ACK mode setup
menu.
If an automatic reply has been selected, then the acknowledgment
will be sent and the radio will switch to the voice channel
selected by the calling station.
If the manual reply mode is selected then the radio will display
“ABLE” and beep once per second. Use the "ABLE" setting, or select
“UNABLE” using the rotary control, then press the ENT key to
transmit the acknowledgment. The radio will switch to the channel
selected by the calling station if “ABLE” was sent, or remain on
the current working channel if “UNABLE” was sent.
If the Manual + Timeout Reply mode is selected then the radio will
display “UNABLE” and beep until “ABLE is selected using the rotary
control and the ENT key is pressed. If 4.5 minutes pass without
the user selecting “ABLE”, the radio will transmit the Unable to
Comply message and remain on current working channel.
While on the selected voice channel the display will alternate
between “INDIVID” and the name or DSC ID of the caller. The name
is displayed if the caller’s DSC ID is in the address book.
3-10
3
.5.7 REVIEWING THE DSC CALL LOGS
3.5.7.1 Routine DSC Calls
The radio retains the last 50 received DSC calls in the DSC Log.
To view the log, press FNC-8 to access the DSC Menu. Use the
rotary control to select Review DSC Log, then press ENT. All
information about the received call, including the received time
and date, will be displayed. Use the rotary control to scroll
though the log. Pressing the ENT key on a log display will prompt
you to either delete the entry or initiate a DSC Call to the
source DSC ID.
Information displayed for GEOAREA, INDIVIDUAL, GROUP, ALL SHIPS
and UNKNOWN message:
Line 1 Message number and Category
Line 2 Received from DSC ID or name
Line 3 UTC Time / Date for when the call was received
Line 4 Channel / Frequency / Position (dependent on type of call)
Line 5 ACK Status
Line 6 Telecommand 1
Line 7 Telecommand 2
Information displayed for PHONE CALL message:
Line 1 - Message number and phone number
Line 2 - Received from DSC ID or name
Line 3 - UTC Time / Date for when the call was received
Line 4 - Call Duration / Channel / Frequency / Position
Line 5 - ACK Status
Line 6 - Telecommand 1
Line 7 - Telecommand 2
Information displayed for DISTRESS CALL / RELAY or ACK message:
Line 1 - Message number and Distress Call / ACK / Relay
Line 2 - Received from DSC ID or name
Line 3 - UTC Time / Date for when the call was received
Line 4 - Position / Time of position fix
Line 5 - Nature of distress
Line 6 - Relay DSC ID if available
Line 7
3.5.7.2 DISTRESS CALL LOG
The radio retains the last 20 DSC Distress calls in the Distress
Log. To view the log, press FNC-8 to access the DSC Menu. Use
the rotary control to select Review Distress Log, then press ENT.
All information about the received call, including the received
time and date, will be displayed. The rotary control may be used
to scroll though the log entries.
The Distress Log is organized by events, that is, all the Distress
Calls sent by or to an individual DSC ID within a 2 hour period
represents a Distress Event with the current status represented by
the last call received.
3-11
If a Distress Event is active, that is, it has not been
acknowledged, and the event is more than 5 minutes from the
original distress call, then the operator may initiate a Distress
Relay* or a Distress Acknowledgement**. While viewing the Distress
Event, press the ENT key. A prompt will allow selection of a
Broadcast Relay, Addressed Relay or Acknowledgement. Select the
type of call, then press the ENT key. If an Address Call is
selected, a destination DSC ID may be entered at the subsequent
prompt. All other information required for the DSC call will be
automatically inserted.
* Care should be taken when sending relay calls for another ship
in distress. A distress relay should only be sent if it has been
confirmed that the coast station did not receive the original
call.
** Distress Acknowledgement should be transmitted to terminate the
call only after consulting with a Rescue Coordination Center or a
Coast Station, and being directed to do so.
The information displayed in the Distress Log contains the
following information:
Line 1 - Time / Date of original distress call
Line 2 - The DSC ID or name for the vessel in distress
Line 3 - Nature of the Distress
Line 4 - Position / Time of Position Fix
Line 5 - Current status (Distress, Relay, ACK)
Line 6 - The source DSC ID for the Relay or Acknowledgement
Line 7 - Time / Date of last DSC call for this event
3.5.7.3 MISSED CALLS
If a received DSC call is not acknowledged by pressing the PTT
switch or a keypad key within 5 minutes, the call is placed in the
Missed Call List.
To view the Missed Call List, press FNC-8 to access the DSC Menu.
Use the rotary control to select Review Missed Calls, then press
ENT. All information about the received call, including the
received time and date, will be displayed. Use the rotary control
to scroll though the log.
Pressing the ENT key will allow you to delete the entry, add to
the DSC List if not already part of that list or respond to the
call. If responding, then a DSC call will be transmitted to the
received DSC ID.
Information displayed for Missed Call List:
Line 1 Message number and Category
Line 2 Received from DSC ID or name
Line 3 UTC Time / Date for when the call was received
Line 4 Channel / Frequency / Position (dependent on type of call)
Line 5 Telecommand 1
Line 6 Telecommand 2
3-12
3.5.7.4 CLASS A CALL DETAIL
The DSC calls described to this point in the manual have consisted
of predefined message formats for commonly used DSC calls. The
predefined versions allow the operator to place calls quickly and
efficiently using minimal additional information input.
Calls that contain more specific information, such as requiring a
data response rather than voice communications, may be created
using the “Class A” build operation. The following paragraphs
describe the structure and organization of Class A calls.
Most Class A calls contain the following information: Format Type,
Priority Category, Telecommand 1 and Telecommand 2. Note that the
type of information available will be dependent on the type of
call being composed. An example would be an All Ships call that
requires no destination DSC ID.
To use the Class A composer, press FNC-8 to access the DSC Menu.
Use the rotary control to select “Class A”, then press ENT.
Prompts will appear for additional information as required. Once
the DSC message construction is complete, instructions will be
given to send the DSC call. See Appendix D in OPR-157S for details
on the information fields.
3.6 USING TEST, CALIBRATION AND DIAGNOSTIC UTILITIES
Enter the service menu by pressing FUNC-ENT and entering the
service menu activation code (contact the factory with the radio’s
serial number to receive the activation code).
A menu allowing you to adjust the clock frequency, 1W power level,
25W power level and transmit the DSC tones and dot patterns.
During all of the service menus PTT is active so that the
transmitter can be tested.
3.6.1 CLOCK TUNING
Select the ‘CLKTUN’ menu and press ENT. The display will show the
clock frequency adjustment value (0-200, 100 is normal setting).
Use the rotary control to adjust the value and press MODE to store
the new setting and exit the adjustment mode.
3.6.2 POWER LEVEL ADJUSTMENT
Select the ‘1W ADJ’ or the ‘25W ADJ’ mode from the service menu.
Press ENT to enter the adjustment menu. The 3 digit display will
show the current power level control setting and the right 3
digits of the 8 character display will show the forward power
reading. Pressing PTT will transmit and the ALC will adjust the
power level to be equal to the setting selected. Press ENT to
store the setting to non-volatile memory and exit the service
menu.
3-13
3.6.3 DSC TONE TRANSMIT
Select the ‘DSC DOT’, ‘DSC 1300' or ‘DSC 2100' selection from the
service menu. Press ENT and the 3 digit display will show ‘ON’,
and pressing PTT will transmit the selected DSC tone or dot
pattern. Press ENT to exit to the main service menu. Press FUNC to
exit the service menu.
3.7 USA CHANNEL LISTING
Channel S/D SHIP TX Ch. Designation
01 D 156.050
01A S 156.050 Port Operations, Commercial
02 --- 156.100 RX Only
03A S 156.150
04A --- 156.200 RX Only
05A S 156.250 (VTS), U.S. Only, Port Ops
06 S 156.300 Intership Safety
07A S 156.350 Commercial
08 S 156.400 Commercial, Non-Commercial
09 S 156.450 Commercial, Non-Commercial
10 S 156.500 Commercial
11 S 156.550 (VTS), Commercial
12 S 156.600 (VTS), Port Ops
13 S 156.650 Bridge-to-Bridge, Navigational
(Manual override to 25 watts)
14 S 156.700 (VTS), Port Ops
15 S 156.750 RX only (Coast to Ship Environmental)
16 S 156.800 DISTRESS AND CALLING
17 S 156.850 Maritime Control
18A S 156.900 Commercial
19A S 156.950 Commercial
20 D 157.000 Port Ops
20A S 157.000 Port Ops, Intership
21A* S 157.050 U.S. Govt ONLY (USCG)
22A S 157.100 U.S. Coast Guard
23 D 157.150 Public Correspondence
23A* S 157.150 U.S. Govt ONLY
24 D 157.200 Public Correspondence
25 D 157.250 Public Correspondence
26 D 157.300 Public Correspondence
27 D 157.350 Public Correspondence
28 D 157.400 Public Correspondence
Channel S/D SHIP TX Ch. Designation
60 --- 156.025 RX Only
61A* S 156.075 Public Correspondence
62A --- 156.125 RX Only
63A S 156.175 Port Ops, Commercial
64 S 156.225 Public Correspondence
65A S 156.275 Port Ops
3-14
66A S 156.325 U.S. Only, Port Ops
67 S 156.375 Commercial, "Bridge-to-Bridge" Nav
(Manual override to 25 watts)
68 S 156.425 Non-Commercial
69 S 156.475 Non-Commercial
70 S 156.525 Digital Selective Calling (DSC)
71 S 156.575 Non-Commercial
72 S 156.625 Non-Commercial
73 S 156.675 Port Ops
74 S 156.725 Port Ops
77 S 156.875 Port Ops, Intership Only
(Manual override to 25 watts)
78A S 156.925 Non-Commercial
79A S 156.975 Commercial
80A S 157.025 Commercical
81A* S 157.075 U.S. Govt ONLY
82A* S 157.125 U.S. Govt ONLY
83A* S 157.175 U.S. Govt ONLY
84 D 157.225 Public Correspondence
85 D 157.275 Public Correspondence
86 D 157.325 Public Correspondences
87 D 157.375 Public Correspondence
88 D 157.425 Public Correspondence
88A S 157.425 Commercial Intership
3.8 International Channel listing
NOTE: Amended International Channel List is identical
to the SEA 157S International Channel List with the
following exceptions:
Channel S/D SHIP TX Ch. Designation
01 D 156.050 Canada Public Correspondence
.................................................................
02 D 156.100 Canada Public Correspondence
.................................................................
04A S 156.200 Canada Public Correspondence
.................................................................
60 D 156.025 Canada Public Correspondence
.................................................................
62A S 156.125 Canada Public Correspondence
................................................................
3-15
3.9 Weather Channel listing
CH Smpx TX 25W SHIPRX SHIPTX Tag
1 D N 162.550 - WEATHER 1
2 D N 162.400 - WEATHER 2
3 D N 162.475 - WEATHER 3
4 D N 163.275 - WEATHER 4
5 D N 161.650 - WEATHER 5
6 D N 162.775 - WEATHER 6
7 D N 162.425 - WEATHER 7
8 D N 162.450 - WEATHER 8
9 D N 162.500 - WEATHER 9
10 D N 162.525 - WEATHR 10
3-16
4. INSTALLATION
4.1 PRELIMINARY CHECK:
Prior to installation, the transmit frequency, peak frequency
deviation and RF power output level should be checked on a
calibrated FM service monitor or equivalent equipment. See
Section 6 of this manual for more detailed procedures.
4.2 SHELF OR OVERHEAD MOUNTING:
See Figure 4.1 for dimension drawings of SEA 157S.
4.3 BULKHEAD MOUNTING:
See Figure 4.2 for Flush Mount Kit Drill Template for SEA 157S
A special bulkhead mounting bracket (SEA P/N KIT-0157-30) is
available from SEA COM which permits through-bulkhead mounting of
the SEA 157S. The required depth behind the bulkhead is
approximately 11.5 inches (290 mm). Contact SEA COM Corp. at
(425) 771-2182.
4.4 POWER SUPPLY WIRING:
Use a 13.6Vdc +/-15% (11.6Vdc to 15.6Vdc) DC power source for
proper operation. Direct connection to the battery or power
supply is recommended. Connect the RED positive (+) power lead to
the positive supply rail. The BLACK negative (-) power lead
connects to the negative supply rail. NOTE: The chassis of the
SEA 157S is connected to the negative supply rail.
CAUTION: If the power wires are connected backward, i.e., reverse
polarity and power is accidentally applied to the radiotelephone,
the fuse will blow. It is also likely that the reverse-polarity
protection diode, D2, which is near the power lead connections on
the main circuit board will also be damaged. Application of
voltages greater than the maximum rated voltage will produce the
same result. (Refer service of this equipment to a qualified
technician.)
4.5 ANTENNA WIRING:
Use only the best available antennas, 50 ohm coaxial antenna
feedline cable and connectors. The antennas must be vertically
polarized. The antenna cables should be terminated with properly
installed PL-259 (Type UHF male) connectors which should be
securely screwed to the antenna connectors on the rear panel of
the transceiver. All antenna feedline connections should be
carefully protected from the weather.
4-1
4.6 EXTERNAL SPEAKER WIRING:
An external speaker can be added with or without the internal
speaker remaining active. Both receiver audio and the internal
speaker are brought out though the interconnect cable. For normal
operation of the internal loudspeaker, the orange wire (INT SPKR)
and blue wire (AF OUT) are connected together. Connect an
external loudspeaker between the blue wire (AF OUT) and the black
wire (GND). For maximum audio volume, the external speaker should
be a high-efficiency, 4 Ohm type rated for 4 watts minimum.
NOTE: Do not attempt to use the "ship's ground" for audio
circuits. Often, confusing audio problems can be avoided if none
of the external speaker wiring is allowed to contact the ship's
ground.
4.7 NMEA 0183 INPUT/OUTPUT, RS232 WIRING:
A navigation signal such as from a GPS receiver, can be connected
to the SEA 157S. A computer can be connected to the RS232 port of
the SEA 157S. Connections for both of these ports can be made at
the 8 pin round connector on the rear panel next to the main
interconnect cable.
4-2
5. THEORY OF OPERATION
Block and schematic diagrams referenced in this section are
located in Section 7 of this manual. See the List Of Figures for
aid in locating applicable reference drawings.
5.1 FREQUENCY SYNTHESIZER:
GENERAL: Refer to the functional block and schematic diagrams.
The SEA 157S makes use of a multi-loop synthesizer system to
provide conversion frequencies for the Receiver, and the
Transmitter. The Main Transmitter synthesizer also serves as the
first conversion loop for the Main Receiver and consists of the
voltage controlled oscillator (VCO) Q1, RF buffers/amplifiers Q4
and Q3, synthesizer LSI chip U10, reference oscillator VCTCXO Y1,
and the loop filter.
VCO: The low-noise VCO is a grounded-gate JFET oscillator
operating in two frequency bands as selected by Q2 and D2. D2 is
"off" for transmit and L5 and L6 set the frequency band to the
155-159mHzrange. D2 is "on" for receive and L6 sets the 176.4-
185.4mHz receiver local oscillator (LO) range. The tuning voltage
from the loop filter is applied to varactors D4 and D5. The
tuning voltage ranges from 1 to 4 volts. As the cathodes of D4 and
D5 are referenced to the +8 volt supply, lower voltages correspond
to higher frequencies. The entire VCO and two stage buffer is on
a separate pc board located in a shielded “pocket” in the chassis
casting.
VCO RF AMPLIFIERS: Q4 and Q3 amplify the VCO signal up to +10 dBm
(10 mW) nominal. The signal is then fed to the receiver mixer U3
via a resistive attenuator and also to the transmitter pre-driver
Q10 via the Main Board diode D3. D3 is turned "on" only during
transmission to supply approximately +10 dBm excitation to the
transmitter amplifier chain.
SYNTHESIZER CHIP: A sample of the amplified VCO signal is
derived from the output of Q3 and fed to the N and A dividers of
U10. The N and A divider modulus is preset by the microcomputer
via the clock, data and enable digital lines. The total frequency
division (N and A) reduces the RF signal down to a 12.5kHz
comparison frequency at U10's internal phase detector. For
example, the total division for transmission on 156.80mHzis
156,800/12.5 = 12544. For a receive frequency of 156.mHz the
required LO frequency is 156.80mHz+ 21.40mHz= 178.20mHzrequiring a
division factor of 178.200/12.5 = 14,256. The 21.85mHz master
reference oscillator is divided by a fixed 1748 modulus to produce
the 12.5kHz reference frequency. The U10 phase detector output at
pin 5 is tri-state and drives the loop filter. A separate lock
detect (LD) output from U10 pin 14 goes low when out of lock. The
LD signal is fed back to the microcomputer which disables the
transmitter in the unlocked state.
5-1
MASTER REFERENCE OSCILLATOR:The master clock is provided by highly
stable VCTCXO at 21.85mHz Y1. This oscillator has a specified
frequency stability of +/-1ppm from –20 to 70 degrees C. The
oscillator output is connected the input of the CMOS gate of the
synthesizer IC, U10 pin 1. The output of this gate, U10 pin 2
provides a buffered 21.85mHz signal to the main and Channel 70
receiver boards.
LOOP FILTER: R64 on the main PCB and R3,R4,R13,C2,C4,C5,and C19
on the VCO PCB comprise the synthesizer loop filter.
5.2 MODULATION CIRCUIT:
TRANSMITTER AUDIO PROCESSING: After a 20dB boost by amplifier IC
U21, located on the main PCB, microphone audio is sent to be
processed by the digital signal processor (DSP), U13, located on
the Mezzanine PCB. The microphone audio signal is applied to the
MICIN input of 16-bit audio CODEC, U8, where it is digitized and
sent to the DSP. The DSP then feeds it through a digital
filter/limiter process which filters the transmitter audio with a
3kHz lowpass filter. It then applies a 6db per octave pre-
emphasis, limits the audio in a low distortion process and finally
filters the audio again with a 3kHz lowpass filter. This method
maximizes the average voice energy within the set deviation limit
while minimizing audio harmonic distortion levels.
DSC DATA: The digital modulation signal is generated internally in
a phase continuous digital sine wave generator. It is then feed
into the transmitter audio processing (within the DSP) at the
input of the pre-emphasis and then applied at a level below the
limiting threshold of the audio processing and factory calibration
for a modulation index of 2.
FREQUENCY DEVIATION CONTROL: The transmitter peak deviation is
controlled digitally by a factory set deviation multiplier
constant which is stored in flash memory (U3 and U4). D2 on the
VCO PCB is switched "on" during receive mode to switch VCO ranges
and to insure that no modulation is applied to the synthesizer
during receive operation.
5.3 MAIN RECEIVER:
GENERAL: The main receiver is a double-conversion, high side
mixing superheterodyne circuit.
RECEIVER RF FRONT END: After passing through the low-pass filter
that is common to both the receiver input and transmitter power
amplifier output, the RF signal from the antenna is applied to the
receiver pin diode-1/4 wave section T/R switch consisting of C1,
L1, C2, and D2 and then passed through the tuned matching network
L2, L3, and C4 to the input of the dual-gate MOSFET RF amplifier
Q1.
5-2
The signal strength is increased by Q1 and passed through the
double tuned matching network made up of C8, L4, C9, L6, C10, and
C11 to the input of the signal splitter formed by T1,R7, and R6.
One output of the signal splitter is applied to the input of
double balanced diode ring mixer U1 while the other output of the
splitter is sent to the Channel 70 receiver.
The mixer U1 is supplied with a +7 dBm local oscillator, high-side
injection signal from the VCO buffer by way of the resistive pad
consisting of R8 and R9. The frequency of the local oscillator is
21.4mHz above the desired receive frequency resulting in a first
intermediate frequency of 21.4mHz at the output of the mixer.
21.4mHz FIRST IF AMPLIFIER: The 21.4mHz output from the mixer
U1 is applied to the input of the dual-gate MOSFET First IF
amplifier Q2. The signal is amplified by Q2 and directed to the
input of the four pole 21.4mHz crystal filter comprised of FL2 and
FL1. The output of the crystal filter is connected to the input of
the FM IF system U2.
450KHz SECOND IF AMPLIFIER: The input stage of the FM IF system U2
consists of a Gilbert cell mixer that is driven by both the
output of the 21.4mHz first IF crystal filter and the
21.85mHzmaster reference oscillator. The resultant output of the
Gilbert cell mixer is a 450KHz second IF signal which applied to
the input of the 15KHz 4 pole ceramic filter FL3. The output of
FL3 is returned to the input of the second IF amplifier located
within U2. The output of the second IF amplifier is passed out of
the FM IF system U2 to the input of the analog switch U3.
Depending on the logic level on pin 10 of the analog switch U3,
the signal will be routed through the 7.5KHz 2 pole ceramic
filter FL4 or the 15KHz 2 pole ceramic filter FL5 and returned to
the limiter-amplifier located within U2.
QUADRATURE DETECTOR: The output of the limiter-amplifier of U2 is
internally fed to the quadrature detector whose phase shifting
network is provided by the ceramic discriminator Disc1. The output
of the discriminator is buffered by an amplifier and the raw
baseband detected audio emerges from U2 on pin 8. This audio
signal is then amplified by the audio buffer and bandpass shaping
amplifier U5 and passed on to the input of the CODEC U8.
DIGITAL DE-EMPHASIS/VOLUME CONTROL CIRCUIT: The CODEC U8 digitally
samples the audio from U2 at 48.000kHz and passes the digitized
signal to the Digital Signal Processing (DSP) IC U13 where it is
split into two signals by a 3kHz lowpass and a 3 KHz highpass
filter. The highpass filtered portion is fed to the squelch
processor described below. The lowpass filtered portion is
adjusted by the digital volume control value, digitally de-
emphasized, applied to the digital squelch gate, and returned to
the CODEC. The CODEC then converts the processed digital audio
back to an analog signal which exits the CODEC on pin 10 and is
passed to the audio amplifier IC, U11, located on the main PCB.
5-3
DIGITAL SQUELCH PROCESSING: As described above, the digitized
receiver audio is filtered by a 3 KHz high pass filter and fed to
the digital squelch processor. It is similar to a traditional
noise activated squelch. The DSP calculates the magnitude of audio
energy above and below 3 KHz and uses this in conjunction with the
squelch threshold setting to intelligently decide whether to open
or close the digital squelch gate.
5.3.1 CHANNEL 70 WATCH RECEIVER:
GENERAL: The 156.525mHz Channel 70 monitor receiver is a single
channel, dual conversion, crystal controlled stand alone FM
receiver. The first IF frequency is 21.4mHzand and the second IF
is 450kHz.
RF FRONT END: RF from hybrid splitter, T1, on the main receiver
board passes through a pad and then a highpass filter to the
source of the low noise, grounded-gate RF preamplifier Q1. After
being amplified by Q1, the signal passes through the three stage,
top coupled bandpass filter consisting of L3, L4, L5 and their
associated capacitors. The output of the bandpass filter is
applied to the input of the active first mixer, U1. A -7 dBm LO
low-side injection local oscillator signal is also provided to the
first mixer by First Local Oscillator circuit described below.
FIRST LOCAL OSCILLATOR: The first local oscillator is an overtone
crystal controlled oscillator/doubler circuit consisting primarily
of Y1, L6, Q2, L7, L8 and their associated components. The
overtone crystal Y1 operates at 67.5625mHz and frequency trimming
is provided by L6. The crystal frequency is doubled by Q2 and the
resulting 135.125mHz LO signal is filtered by the bandpass filter
consisting of L7, L8 and their associated capacitors.
21.4mHz Filter/First IF AMPLIFIER: The output of the mixer U1 is
directed through the 21.4mHz, 4 pole crystal FL1 to the input of
the first IF amplifier Q3. The output of Q3 is applied to the
input to of the FM IF system U4.
450kHz SECOND IF AMPLIFIER: The input stage of the FM IF system U4
consists of a Gilbert cell mixer that is driven by both the
output of the 21.4mHz first amplifier Q3 and the 21.85mHz master
reference oscillator. The resultant output of the Gilbert cell
mixer is a 450kHz second IF signal which applied to the input of
the 450kHz ceramic filter FL2. The output of FL2 is returned to
the input of the second IF amplifier located within U4. The
output of the second IF amplifier is passed out of the FM IF
system U2 through the 450kHz ceramic filter FL3 and returned to
the limiter-amplifier located within U2.
QUADRATURE DETECTOR: The output of the limiter-amplifier of U4 is
internally fed to the quadrature detector whose phase shifting
network is provided by the ceramic discriminator Disc1. The output
of the discriminator is buffered by an amplifier and the raw
baseband detected audio emerges from U4 on pin 8.
5.4
This audio signal is then fed to the CODEC (U8) to be digitized.
The audio output is continuously monitored by the DSP, looking for
the DSC dot pattern.
Voltage Stabilization: U3 provides a stabilized +5Vdc to active
mixer U1 and FM IF system and U2 provides a stabilized +8Vdc for
the local oscillatorQ2 and other voltage sensitive receiver
circuitry.
5.4 TRANSMIT AMPLIFIER CHAIN:
GENERAL: Referring to Sheet 4 of the Mainboard Schematic Diagram,
the transmit amplifier chain of the SEA 157S consists of the
discrete RF amplifiers Q10 and Q9 and a two-stage hybrid RF power
amplifier module U16.
PRE-DRIVERS: The buffered output signal from the frequency
synthesizer is first amplified by Q10 and its output is coupled to
the input of Q9. Q9 further amplifies the signal and applies it to
the input (IN) of the power amplifier module U16. The RF signal
from Q9 is however only available to the input of the power
amplifier module when in the transmit mode and 13Vdc is present on
13V_TX bus to power Q10.
FINAL AMPLIFIER: U16 is a hybrid power amplifier module
containing two gain stages. When the radio is on, 13.6Vdc is
applied to the power amplifier module at all times. The power
amplifier module will however only produce RF power when the
radio is in the transmit mode and the RF signal from Q9 is
available at the module input (IN). The amount of RF output
produced by the power amplifier module is dependent on the level
of bias voltage available to pin 2(PA) of the power amplifier
module and to Q9 via R5, R6, and L5. This bias voltage is
controlled by the amplifier consisting of Q5, Q13 and their
associated components and the amount of control voltage available
at the 1W_25W bus.
5.5 ANTENNA INTERFACE CIRCUITS:
TRANSMIT/RECEIVE SWITCHING: Antenna changeover between transmit
and receive is accomplished by the PIN diode switches D33 on the
Mainboard and D1 on the Receiver Board. In the transmit mode,
voltage is applied to the 13_VTX bus and current passes through
R43, R72, R62, L7, R2, R2A, L1, and D33 on the mainboard and
finally to ground through L1 and D1 on the Receiver board. This
current through D33 causes it to become forward biased and pass RF
power from the power amplifier module to the low-pass filter
consisting of L2, L3, L4, and their associated capacitors. The DC
current flow though D1 also causes it to become forward biased and
short-circuits the input to the receiver. The short-circuit in
addition causes the input impedance of the 1/4 wave matching
section comprised of C1, L1, and, C2 on the Receiver board to
become high and effectively isolates the receiver from the
transmitter RF. 5.5
TRANSMIT/RECEIVE ANTENNA FILTERING: The 7-section low-pass filter
comprised of C4, L1, C5, C7, L2, C126, C8, L3, C127, C9, L4, and
C10 provides VHF and UHF attenuation of the transmitter harmonics
and receiver images.
5.6 AUTOMATIC RF POWER CONTROL (APC) AND TX LOGIC:
In transmit mode a negative feedback control system continuously
monitors and, if necessary, corrects the output power level at the
antenna terminals. C119 samples the RF voltage at the RF power
amplifier module output terminal (4). Diode D34 converts this RF
signal to a DC level representing the output power level. This DC
power level signal is fed to one channel of the internal A/D
converter of CPU IC, U1, located on the Mezzanine board. The
digitized signal is processed by a power control routine, which,
through the D/A converter U17, drives the DC amplifier consisting
of Q5 and Q13 to provide the correct DC supply voltage to Q9 and
bias to the power amplifier module U16. This RF power level
closed-loop system thus maintains the RF output power at the
proper level. Two references are used in the control routine which
correspond to 1 watt or 25 watt output levels. When adjusted
according to the alignment instructions, the APC system will
closely maintain the 1W or 25W output level (as selected) over a
wide range of power supply voltage and ambient temperatures. In
the unlikely event that the automatic power control system should
fail, the power amplifier cannot produce much more 30 watts.
5.7 TX LOGIC DETECTOR: The DC level from rectifier D34 which is
used by the above APC circuit is also used by the CPU to determine
when the output power level exceeds 1/2 watt and turns on the TX
annunciator on the front panel liquid crystal display.
5.8 POWER and AUDIO CIRCUITS:
All receiver volume, squelch, beep and muting processes are
performed within the DSP U13. The processed audio is sent through
the CODEC U8 to U11 where it is amplified up to a maximum of 4
watts.
Most of the SEA 157S internal circuitry is powered from the 13
volt switched (13VSW) bus. This is derived directly from the fused
and filtered input voltage from the main power source via Q1-A.
The 13V_TX bus is also powered by the 13VSW bus by way FET switch
Q-B.
The audio power amplifier and a number of control switches and
voltage regulators are powered by the +13VSW bus. The +5Vdc
regulator U9 operates from this bus while the +3.3Vdc regulator U2
and the +1.6Vdc regulator U5 derive their power from the +5Vdc
bus.
Both the Receiver and the VCO modules operate from the 13VSW bus
and contain their own regulators, U4 and U1 respectively.
5.6
5.9 MICROCOMPUTER CIRCUITRY:
Referring to SEA 157S Mezzanine Board schematic diagrams:
MICROPROCESSOR: U1 is a Toshiba TMP92CY23 single chip
microprocessor. This IC handles all the top level processing of
data, including keypad and serial port input/output, display
output, power management and other system functions. The
microprocessor also oversees the activity of the digital signal
processor chip, U13. Program instructions for this processor are
contained in two serial Flash ICs, U3 and U4, which may be field
upgraded via the radio's RS-232 serial port. Additional RAM needed
for efficient processing is provided by IC U2. Crystal Y1, which
is doubled by the CPU's internal circuitry to 19.66mHz provides
all the timing requirements for the CPU.
DIGITAL SIGNAL PROCESSOR: U13 is a Texas Instruments TMS320VC5410
DSP IC. This chip performs digital processing of all the audio
signals passing through the radio. Received audio is digitally
sampled at 48kHz by audio CODEC, U8, and passed to the DSP. The
DSP performs receiver and transmitter audio processing, filtering,
volume control, beep generation, and squelch detection and gating.
In addition, the DSP performs all of the low-level DSC signal
processing, passing its output to the CPU for top-level decoding.
The DSP's processed data, or internally generated DSC modem data,
is returned to the CODEC for conversion to analog prior to output
to the transmitter or speaker.
CODEC: U8 is a Texas Instruments TLV320AIC23B high performance
stereo audio CODEC. The CODEC handles the conversion of analog
transmit and receiver audio to the digital domain for processing
by the DSP. The CODEC also handles the conversion of the digital
data containing the processed transmit and receive audio back to
the analog domain.
SERIAL PORTS: The SEA 157S hosts one NMEA0183 port and one RS-232
type port. The NMEA0183 input port is optically coupled to the CPU
through U8; the output is provided via FET transistor Q4. The RS
type port is accomplished with transistors Q15 and Q16 and
associated circuitry. All baud rates and timing functions are
derived from the CPU system oscillator.
REAL-TIME CLOCK: The SEA 157S contains a real-time clock IC, U16,
which provides uninterrupted maintenance of real world time. Power
for this IC is supplied by a separate line that bypasses the
radio's power switch, ensuring that the time settings are
maintained even when the radio is switched off. A 32.768kHz
crystal oscillator provides a stable reference for this IC.
REFERENCE OSCILLATOR: A 21.850mHz Voltage-Controlled Temperature
Compensated Crystal Oscillator (VCTCXO), Y1, located on the main
PCB, provides a stable frequency reference for all receive and
transmit functions. The frequency of this oscillator is controlled
by the CPU, and may be adjusted for optimum performance, if
necessary. 5.7
NON-VOLATILE DATA STORAGE: Permanent memory capability for Scan
lists, special channel programs, configuration and user
parameters, etc., is provided by the serial Flash ICs, U3 and U4.
No memory backup batteries are required.
RESET AND WATCHDOG PROTECTION CIRCUIT: U15 monitors the 3.3Vdc
supply to the CPU and DSP processing circuitry. At power up, this
IC provides a 200 millisecond pulse to assure initial CPU and DSP
operation. Thereafter, if the supply drops below 3.0Vdc, U15 pulls
the reset output low until the supply returns to normal. Even
momentary brownout conditions will cause a reset condition. U15
also contains a watchdog circuit. The watchdog input, pin 4, must
be strobed by the processor at least once per second to avoid
triggering a reset. This protects the radio in the unlikely event
that the CPU should fail to function properly.
5.10 KEYPAD/KEYPAD LIGHTING:
KEYPAD: Primary control of the SEA 157S is through the 15 key
keypad. This keypad is of the conductive rubber type and is
backlit with internal LEDs. The keypad PCB contacts and
backlighting components are part of the Mainboard PCB. The
backlighting LEDs are configured in four series strings and light
level is controlled by the DSP through pin 2 of the octal DAC U17.
The DAC output is buffered and amplified by Q7 and Q8. Sixteen
intensity levels are provided.
5.11 DISPLAY/DISPLAY LIGHTING:
DISPLAY: The front panel display is a LED backlit, 128 by 64 LCD
graphic module. Various display configurations are provided which
permit the operator to monitor all the various radiotelephone
parameters such as channel number, power level, memory mode, etc.
The display data is provided by the system CPU via the higher 8
bits of the 16 bit data bus.
5-8
6. MAINTENANCE
NOTE: In order to avoid making unnecessary adjustments it is best
to first assess the basic transceiver performance using the steps
outlined in Section 6.3 below.
6.1 GENERAL
BASIC DISASSEMBLY:
NOTE: No disassembly of the unit is generally required for
calibration of the unit.
1. Prepare a clean surface in the work area. Static-free
precautions are recommended. Place radiotelephone on work
surface and remove the eight #4 self tapping screws which
fixes the front panel bezel in place. The front panel bezel
may then be removed, providing access to the interior of the
radiotelephone.
CHASSIS DISASSEMBLY:
The Main PCB is not field removable from the chassis casting.
Contact the factory for return authorization if the main PCB is
damaged.
6.2 RECOMMENDED TEST EQUIPMENT:
1. 13.6 volt, regulated DC power supply with ammeter, rated for
minimum 6 amps continuous duty.
2. Calibrated RF wattmeter (Bird Model 43) with 25 watt and 1
watt, 150mHz elements and a 50 ohm 25 watt load or power
attenuator.
3. Volt-ohmmeter plus RF probe. eg: Fluke 75 plus Fluke 85RF
probe.
4. VHF frequency counter, accurate to 10 Hz resolution.
5. Calibrated frequency deviation meter.
6. Sinewave audio signal generator.
7. Calibrated RF signal generator with FM capability, 50 ohm
output impedance and minimum 40 watt reverse power
protection.
8. Audio distortion (SINAD) and audio voltmeter.
9. Four Ohm, four Watt resistive audio load.
10. Spectrum analyzer, 1 to 1000mHz, 1 KHz resolution.
11. Oscilloscope. (50mHz bandwidth required for receiver first
IF alignment.)
12. 50 ohm, 20 or 30 dB RF power attenuator.
13. VHF marine FM monitor receiver.
6-1
6.3 BASIC PERFORMANCE TESTS:
GENERAL:
NOTE: No disassembly is required to perform basic performance
tests. The orange audio output wire and the yellow internal
speaker wire must be connected together if internal speaker
operation is desired.
1. DISPLAY/KEYPAD AND MAIN MEMORY CHECK: When the main power is
turned on, the display will cycle through a self-check
sequence. Following this self-check cycle, the front panel
will revert to the normal RADIO front panel indication.
2. NON-VOLATILE MEMORY FUNCTION CHECK: Change the priority
channel to a new channel number. eg: Select USA or INT
channel list, then push, 1 followed by 3 to select Channel
13, then push and hold the ENT key until the Channel
Operation menu is displayed. Use the rotary control to select
“Make PRI Channel” and then press the ENT key. The radio will
return to the main display and PRI will be displayed on
Channel 13. Cycle radio power OFF then ON. Push 16 key and
then push 1 followed by 3, the radio will go to Channel 13
and PRI should be on the display. Reset the priority channel
to the desired channel number (USA Channel 16 is
recommended).
BASIC TRANSMITTER TESTS:
Set up the equipment as shown in Figure 6.1, "Transmitter Test
Setup".
1. TRANSMITTER FREQUENCY AND POWER CHECK: Key the transmitter
on channel 16 (156.800mHz). The frequency should read within
+ 780 Hz of the assigned frequency at room temperature. The
wattmeter should read 25 + 2 watts in the 25 watt mode and
0.7 to 1.0 watt in the 1 watt mode. Repeat this test on
channels 01 (156.050mHz) and 88 (157.425mHz). During
transmission the TX annunciator should be displayed when
either the 1 watt or 25 watt mode is selected. The DC current
should not exceed 6 amperes in the 25 watt mode.
2. TRANSMITTER PEAK FREQUENCY DEVIATION CHECK: Key the
microphone on the desired channel and speak in to the
microphone in a normal speaking voice. Verify that the peak
deviation averages more than 4 KHz but does not exceed 5 KHz.
Listen for "clean" sounding audio on a good monitor receiver.
3. TRANSMITTER AUTO POWER REDUCTION AND OVERRIDE CHECK: Set the
radiotelephone to channel 13 USA. Verify that the 1 watt
(1W) annunciator is ON and that the transmitter power is 1
watt unless manual override is used (Holding down the FUNC
key while transmitting). The 1W/25W display flag will
indicate the current transmit power level.
Repeat on channel 67 USA.
6-2
BASIC RECEIVER TESTS:
Set up the equipment as shown in Figure 6.2, "Receiver Test
Setup".
1. RECEIVER SENSITIVITY AND AUDIO POWER CHECK: Select the USA
channel list. Set both the receiver and signal generator
frequency to channel 16 (156.800mHz). Set the squelch
threshold to open. Apply 1000 Hz sinusoidal, 3 KHz peak
deviation modulation to the signal generator. Start with the
signal generator set to approximately 1 millivolt (-47 dBm)
amplitude.
Set the volume to maximum. The audio voltmeter should read
about 4 volts RMS. Reduce volume to approximately 50% audio
power (2.8 volts RMS on the audio voltmeter).
Reduce signal generator RF amplitude until 12 dB SINAD is
obtained. This should occur at approximately 0.3 microvolts
(-117 dBm) or less. Repeat check on channel 01A (156.050mHz)
and weather channel 1 (162.550mHz).
2. SQUELCH SENSITIVITY CHECK: Turn off signal generator RF
output. Increase the squelch threshold until the squelch
just closes. Start with the signal generator RF amplitude at
minimum setting and increase slowly until the squelch just
opens. The signal generator amplitude should not exceed 0.2
microvolts (-121 dBm).
3. MODULATION ACCEPTANCE CHECK: This test checks for proper
alignment of the receiver. Set the signal generator and
receiver to channel 16 (156.800mHz). Set the signal
generator modulation to 1 KHz sinusoidal, 3 KHz peak
deviation. Set the signal generator amplitude to obtain 12 dB
SINAD. Increase the signal generator amplitude 6 dB (double
the output voltage) and then increase the peak deviation
until the SINAD ratio drops back to 12 dB SINAD. The final
deviation should be 7 KHz or greater.
6.4 TRANSMITTER ALIGNMENT (TUNE UP PROCEDURE):
GENERAL: Avoid making unnecessary adjustments. Some or all of
the following procedures should be performed only after
identifying specific problems during the Basic Performance Tests,
Section 6.3 above.
Transmitter calibration should be performed by qualified service
technicians using the proper test equipment and only with specific
factory authorization. To obtain authorization, contact the
factory with the serial number of the unit for an authorization
code.
6-3
Enter the service menu by pressing FUNC-ENT and entering the
service menu activation code. The various adjustments are
selectable by rotating the front panel control and pressing ENT
when the desired adjustment is displayed. The service menu allows
adjustment of deviation, clock frequency, 1W power level, 25W
power level. DSC transmitted high tone, low tone and dotting
pattern are also available for testing purposes. During all of the
service menus PTT is active so that the transmitter can be tested.
Set up equipment as shown in Figure 6.1, "Transmitter Test Setup".
NOTE: In the event of synthesizer malfunction (unlocked
condition) all display annunciators will flash repeatedly, the
computerized operating system will fail to respond and
radiotelephone transmit function will be inhibited.
1. Ensure that a 50 ohm, 25 watt power load or power attenuator
is connected to the antenna terminals. Ensure that the DC
power source is supplying 13.6 + 0.5 volts to the radio power
lead (Red lead positive, Black lead negative) under 25 watt
transmit conditions. DO NOT EXCEED 16 VOLTS UNDER ANY
CONDITION. If the transmitter is operated at 25 watts output
for long periods, carefully monitor the temperature of the
chassis for evidence of excessive heating.
2. TRANSMITTER FREQUENCY: Place the radio on any desired
channel. Enter the service menu and select the “CLKTUN”
mode. Push microphone push-to-talk button (PTT) to key
transmitter on any desired channel. Rotate the front panel
control until the transmitter is within 100 Hz of the
assigned frequency. The display will show an adjustment of
0-200 and will typically be approximately 100. Press “ENT”
to store the setting. All other transmitter and receiver
channel frequencies are automatically set by this adjustment.
3. TRANSMITTER POWER: Set the radiotelephone to channel 14
(156.700mHz) or any other channel in that range. Select 25
watt output level. Enter the setup mode and select the “25W
ADJ” mode. (NOTE: Avoid prolonged transmitter testing on
the emergency channel (16)). Key the transmitter and adjust
the front panel rotary control for exactly 25 watts output.
Press “MODE” to store the value. Use a 25 watt wattmeter
element for maximum accuracy. Select “1W ADJ” in the setup
menu and temporarily adjust the front panel rotary control
for minimum output power. The TX annunciator on the front
panel display should extinguish, even though the transmitter
is keyed. Change wattmeter element to a 1 watt unit for
maximum accuracy and adjust for 0.95 watts. Press “MODE” to
store the setting. Change wattmeter element back to 25
watts. Check channels 01 and 99 for 25 + 2 watts in the 25
watt mode and 0.7 to 1 watt in the 1 watt mode. The TX
annunciator should now come on in either the 1 watt or 25
watt modes when transmitting.
6-4
5. TRANSMITTER PEAK FREQUENCY DEVIATION:
NOTE: The DSP transmit audio processing adjusts the audio
gain to a wide range of audio input levels. The deviation
adjustment sets the transmitter deviation level and is not a
microphone gain adjustment. Once properly factory set it
should not require readjustment for the life of the unit.
Connect an audio sinewave generator to the microphone
terminals. If the audio generator amplitude cannot be
attenuated below 5 millivolts at the microphone terminals,
insert a 10 Kohm or greater resistor between the audio source
and the external microphone terminal. Set the audio
generator to 1 KHz. Enter the service menu and select the
deviation adjustment as described above. Key the transmitter
and watch the deviation meter while varying the audio
frequency for maximum deviation. Once the maximum is found,
adjust the deviation using the front panel control for 4.8
KHz peak deviation. The LCD display will show a deviation
setting between 0 and 200 and should typically be about 100.
Press the ENT key to store the deviation setting. The
resulting audio level at the external microphone terminals
should be approximately 40 millivolts peak-to-peak or 14 mv
RMS. Now set the generator to 2500 Hz and verify that the
deviation does not exceed 5 KHz peak under any amplitude
condition up to at least 400 millivots RMS at the microphone
terminals. Remove the series dropping resistor from the
audio generator path if necessary to achieve this audio drive
level.
Disconnect the audio generator. Key the transmitter and
speak loudly into the microphone to verify that the frequency
deviation does not exceed 5 KHz. Now speak at normal volume
into the microphone and verify that the deviation averages 4
KHz or more. NOTE: The particular damping characteristics
of the deviation meter must be taken into account since most
deviation meters will overshoot on voice peaks. Listen for
"clean" audio on a good monitor receiver.
6. SPECTRAL PURITY: Connect a 1000mHz spectrum analyzer through
the power attenuator and verify that harmonics or spurious
signals do not exceed -60 db with respect to 25 watts (-16
dbm) during both modulated and unmodulated conditions.
Change to 1 watt output power mode and verify that harmonics
or spurs do not exceed -46 dB with respect to 1 watt (-16dbm)
during both modulated and unmodulated conditions. CAUTION!
Spectrum analyzer overload will lead to erroneous results,
especially at the transmitter harmonic frequencies. To avoid
overload, 60 or 70 minimum attenuation is usually required
between the transmitter output terminals and the first mixer
of the spectrum analyzer, regardless of the center frequency
and span being viewed.
6-5
6.5 RECEIVER ALIGNMENT:
GENERAL: The receiver is factory aligned and has no field
serviceable adjustments. If specific receiver performance
problems are identified, contact the factory for return
authorization.
6-6
135.125MHz
Q1
SA-606
21.4MHz
CH 70
67.56MHz Q2
RFIN
450K 450K
CH70 AF
21.850MHz CLK
BPF
DISC1
OSC/DBLR
CH70 RCVR CLK
RECEIVER
MODULE
RXAF
U2
F5
F4
DISC 1
U1
Q2
F1,F2
21.4MHz
F3
450KHz
Q1
BPF
SA 606
CH70 RECEIVER
U16
SAV-6
ANTENNA
TX IN
1/25W
Q10Q9
DRIV
PA
Q13
Q5
D35
LPF
+13TX
+13V
D33
+3VRX
VCO MODULE
U10 MB15E03
CLKTN
TXAF
PLLCS
SPI.DO
SPICLK
Q2 Q4 Q3
Y1
21.850MHz
-R -N
U12 U12
3VTX
ONKEY
LCD
DISPLAY
CONTRAST
U17
KEYPAD
+
-
1/25W
CLKTN
Q1B
Q1A
Q2
Q3
Q14
Q8
Q7
U7
TLV5628
LEDS
D17-D32
+13VSW
128 X 64
+13TX
+13VSW
U21
+13VSW
SPKR
AF
FLASH
uC
U1
9.8304MHz
Y1
DSP
U13
SERIAL FLASH
REAL
TIME
CLOCK
CODEC
WATCH
RESET
DOG
TMP XXXX
SPI_DO
RS232
NMEA
CH70 AF
RX AF
TX AF
RXAF OUT
SPICLK
PLLCS
Y2
32.768KHz
DISPLAY
KEYPAD
MIC AF
18.432MHz
Y3
VCTCXO
SEA 157S FUNCTIONAL BLOCK DIAGRAM
BACKLIGHTING
KEYPAD
BACKLIGHTING
COMPUTER BOARD
Fig 7.1
Fig 7.2.1
Fig 7.2.2
Fig 7.2.3
Fig 7.2.4
Fig 7.2.5
Fig 7.3
Fig 7.4
SEA157S Mezzanine P11.sch-2 - Fri Aug 06 14:02:03 2010
Fig 7.5.1
SEA157S Mezzanine P11.sch-1 - Fri Aug 06 14:05:25 2010
Fig 7.5.2
Fig 7.6

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