Ericsson EDACS Monogram Series User manual

ericssonzericssonz
Maintenance Manual
MONOGRAM SERIES
EDACSTrunking Portable
800 MHz

AE/LZB119 1647 R1A
2
NOTICE!
This manual covers Ericsson and General Electric products manufactured and sold by Ericsson Inc.
NOTICE!
Repairs to this equipment should be made only by an authorized service technician or facility designated by the supplier. Any
repairs, alterations or substitution of recommended parts made by the user to this equipment not approved by the
manufacturer could void the user's authority to operate the equipment in addition to the manufacturer's warranty.
NOTICE!
The software contained in this device is copyrighted by Ericsson Inc. Unpublished rights are reserved under the copyright
laws of the United States.
This manual is published by Ericsson Inc., without any warranty. Improvements and changes to this manual necessitated by
typographical errors, inaccuracies of current information, or improvements to programs and/or equipment, may be made by
Ericsson Inc., at any time and without notice. Such changes will be incorporated into new editions of this manual. No part
of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including
photocopying and recording, for any purpose, without the express written permission of Ericsson Inc.
CopyrightAugust 1996, Ericsson, Inc.

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TABLE OF CONTENTS
Page
SPECIFICATIONS...........................................................................................................................................3
INTRODUCTION ............................................................................................................................................9
STANDARD RADIO FEATURES ...........................................................................................................9
Carrier Control Timer (CCT)..............................................................................................................9
Audio Alert Beeps ..............................................................................................................................9
Low Battery Alert...............................................................................................................................9
Power Up Self Test.............................................................................................................................9
CONVENTIONAL FEATURES...............................................................................................................9
Manual DTMF Operation...................................................................................................................9
TRUNKED FEATURES (EDACS/GEMARC).........................................................................................11
Preprogrammed DIG/DTMF Numbers...............................................................................................11
HOME........................................................................................................................................................11
Keypad Lock.......................................................................................................................................11
Power Up System/Group ....................................................................................................................11
Manual Individual Calls......................................................................................................................11
Manual Interconnect ........................................................................................................................... 11
Store....................................................................................................................................................11
Recall Last Number Send ...................................................................................................................11
EDACS (ONLY) FEATURES...................................................................................................................11
Group Scan ......................................................................................................................................... 11
Automatic Login.................................................................................................................................11
System/Group Selections....................................................................................................................11
Conventional Failsoft..........................................................................................................................11
SCAT..................................................................................................................................................11
Base/Mobile Operation.......................................................................................................................11
Priority System Scan (Optional) .........................................................................................................11
Emergency (Optional).........................................................................................................................12
Wide Area Scan (Optional).................................................................................................................12
Dynamic Regrouping (Optional).........................................................................................................12
GE-MARC (ONLY) FEATURES .............................................................................................................12
Talk-Around (Direct Mode)................................................................................................................12
SYSTEM DESCRIPTION................................................................................................................................12
EDACS ......................................................................................................................................................12
CONVENTIONAL MODE .......................................................................................................................13
GE-MARC.................................................................................................................................................13
Operational Modes..............................................................................................................................14

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Idle Mode............................................................................................................................................14
Wait Mode ..........................................................................................................................................14
Ready Mode........................................................................................................................................14
GLOSSARY OF GE-MARC TERMS .......................................................................................................15
Idle Mode............................................................................................................................................15
Wait Mode ..........................................................................................................................................15
Ready Mode........................................................................................................................................15
Busy Tone...........................................................................................................................................15
Acquisition Tone.................................................................................................................................15
Collect Tone........................................................................................................................................15
Group/Individual Tones......................................................................................................................16
RADIO OPERATION.......................................................................................................................................16
USER INTERFACE...................................................................................................................................16
Turning The Radio ON/OFF...............................................................................................................16
ALERT TONES................................................................................................................................................16
EDACS APPLICATIONS .........................................................................................................................16
GE-MARC APPLICATIONS....................................................................................................................17
ERROR MESSAGES........................................................................................................................................17
KEYPAD LOCK...............................................................................................................................................18
RF BOARD THEORY OF OPERATION 650-020-0002.................................................................................18
DESCRIPTION..........................................................................................................................................18
CIRCUIT ANALYSIS ......................................................................................................................................18
RECEIVER SECTION ..............................................................................................................................18
RF Amplifier and 1st Mixer................................................................................................................18
1st IF Filter and Amplifier ..................................................................................................................18
2nd Mixer and Detector ......................................................................................................................19
TRANSMITTER SECTION......................................................................................................................19
Synthesizer Switching and Buffering..................................................................................................19
Power Module and Antenna Switching Module..................................................................................19
Forward Power Detector and APC......................................................................................................19
PLL CIRCUIT DESCRIPTION.................................................................................................................19
VCO and Buffer Amplifier..................................................................................................................19
PLL IC (U105) AND LOOP FILTER........................................................................................................20
Lock Detector......................................................................................................................................20
Power Switching and Voltage Regulator.............................................................................................20
DIGITAL BOARD THEORY OF OPERATION 650-010-0003......................................................................20

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CIRCUIT ANALYSIS......................................................................................................................................20
MICRO CONTROLLER U701 .................................................................................................................20
Operating Program..............................................................................................................................21
Clock Circuitry ...................................................................................................................................21
Display Interfacing..............................................................................................................................21
RF Board Interfacing..........................................................................................................................21
Audio Signal Processor Control..........................................................................................................21
Address Demultiplexing .....................................................................................................................21
Address Decoding and Processor Control Outputs.............................................................................22
FLASH EEPROM U703............................................................................................................................22
RAM U707 ................................................................................................................................................22
MODEM U702..........................................................................................................................................22
High-Speed Data Conversions............................................................................................................23
Address Demultiplexing .....................................................................................................................23
Address Decoding...............................................................................................................................23
Reset Logic.........................................................................................................................................23
Clock Circuitry ...................................................................................................................................23
SERIAL NUMBER ROM U706................................................................................................................23
AUDIO SIGNAL PROCESSOR U804......................................................................................................24
Receive Audio Paths...........................................................................................................................24
EDACS & Conventional RX Audio Modes.................................................................................24
High-Speed Data Limiter.............................................................................................................24
Low-Speed Tone/Data Decoding.................................................................................................24
GE-MARC Mode RX Audio.......................................................................................................24
GE-MARC Tone Decoding.........................................................................................................25
Receive Noise Squelch ................................................................................................................25
Receive Alert Tones ....................................................................................................................25
Transmit Audio Paths .........................................................................................................................26
High-Speed Data Encoding .........................................................................................................26
GE-MARC Busy Tone Encoding ................................................................................................26
DTMF Tone Encoding.................................................................................................................27
5-VOLT REGULATOR U801...................................................................................................................27
DISPLAY BOARD THEORY OF OPERATION 650-170-0001.....................................................................27
DESCRIPTION.................................................................................................................................................27
CIRCUIT ANALYSIS...............................................................................................................................27
Control Switches.................................................................................................................................27
Liquid Crystal Display (LCD) ............................................................................................................27
PERSONALITY EEPROM U104.............................................................................................................28
DTMF ENCODER U803...........................................................................................................................28

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MICROPHONE AND SPEAKER.............................................................................................................28
INTERNAL/EXTERNAL SPEAKER/MIC. SWITCH .............................................................................28
DISASSEMBLY...............................................................................................................................................28
FRONT PANEL ASSEMBLY REMOVAL AND REPLACEMENT.......................................................28
To remove the front panel assembly: ..................................................................................................28
To replace the front panel assembly:...................................................................................................28
DIGITAL PRINTED CIRCUIT BOARD REMOVAL AND REPLACEMENT......................................29
To remove the Printed Circuit Board:.................................................................................................29
MICROPHONE AND SPEAKER REMOVAL AND REPLACEMENT .................................................29
To remove the microphone and speaker:.............................................................................................29
KEYPAD BOARD REMOVAL AND REPLACEMENT.........................................................................29
To remove the Keypad Board:............................................................................................................29
RF BOARD REMOVAL AND REPLACEMENT....................................................................................29
To remove RF board:..........................................................................................................................29
PTT Switch Assembly Removal and Replacement:............................................................................30
TROUBLESHOOTING....................................................................................................................................30
VOLTAGE CHART..........................................................................................................................................34
BATTERY CHARGING AND CARE..............................................................................................................37
FOR BEST PERFORMANCE...................................................................................................................37
PARTS LIST.....................................................................................................................................................38
COMPONENT PINOUT ..................................................................................................................................45
SYSTEM WIRING DIAGRAM .......................................................................................................................47
KEYPAD/DISPLAY BOARD SERVICE OUTLINE ......................................................................................48
SCHEMATIC DIAGRAMS:
PTT SWITCH BOARD .............................................................................................................................49
KEYPAD/DIGITAL BOARD....................................................................................................................50
RF BOARD.......................................................................................................................................................51
DIGITAL BOARD (2 SHEETS) ......................................................................................................................52
BLOCK DIAGRAM .........................................................................................................................................54

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SPECIFICATIONS
Input Voltage: 7.5 VDC (Nominal)
Dimensions (Typical) (HxWxD): Less Antenna
7” x 2.5” x 1.5”
(17.78 x 6.35 x 3.81 cm)
Weight Radio with Medium Capacity Battery: 23.03 oz (653 g)
Ambient Temperature Range: -22°F to +140°F
(-30°C to +60°C)
Relative Humidity: 95% at 122°F (50°C)
Altitude:Operational: 15,000 ft (4,572 m)
In Transit: 55,000 ft (16,764 m)
Display: 7 Character Alphanumeric
Memory Levels: 16, 128 EDACS Systems/Groups
9 Areas/9 Groups GE•MARC V
Programming: PC, IBM®, or IBM compatible
TRANSMITTER
Frequency Range (MHz): 806-824 851-869 Talk Around
Frequency Separation (MHz)
(No Degradation) 18
RF Power (Watts): 2 (±10%)
Modulation Limiting (kHz): 5 max
FM Hum And Noise (dB): -40 (companion Rx)
Conducted Spurious (dB): -65 (-30 dbm)
Frequency Stability (PPM): ≤1.5
Channel Spacing (kHz): 25 / 12.5 (NPSPAC)
Audio Response: EIA
Audio Distortion: ≤5%
RECEIVER
Frequency Range (MHz): 851-869
Frequency Separation (MHz): 18
Sensitivity (12 dB SINAD) (dBM): -116 (0.35µV)
Selectivity
@ 25 kHz (dB): -65
@ 12.5 kHz (dB) NPSPAC: -20
Intermodulation (dB): -65
Spurious Response Image Rejection: (dBc) -65
Frequency Stability (PPM): ≤1.5
Channel Spacing (kHz): 25 / 12.5 (NPSPAC)
Audio Output (mW): 400
Distortion (at Rated Audio): ≤10%

AE/LZB119 1647 R1A SPECIFICATIONS
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ENVIRONMENTAL SPECIFICATIONS U.S. Military Spec 810C U.S. Military Spec 810D
Standard Methods & Procedures Methods & Procedures
Low Pressure 500.1/1 500.2/1,2
High Temperature 501.1/1 501.2/1,2
Low Temperature 502.1/1 502.2/2
Temperature Shock 503.1/1 503.2/1
Solar Radiation 505.1/1 505.2/2
Humidity 507.1/2 507.2/2
Blowing Dust 510.1/1 510.2/1
Vibration 514.2/8,10 514.3/1
Shock 516.2/1,2, & 5 516.3/1,4
REGULATORY DATA
Frequency Range (MHz) 806-870
FCC Type Acceptance F3JETP4800
RF Output 2 Watts
FCC Rules 22, 90
DOC Type Number 287 195 105A

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INTRODUCTION
The EDACS Monogram Portable Radio is a rugged,
lightweight unit which is housed in a molded Lexan front
assembly and an aluminum rear casting. The radio provides
reliable service in the 800 MHz band and contains new Dual
Format technology that enables the radio to operate within a
GE-MARC trunked system and an EDACS trunked system.
The radio normally transmits in the 806-824 MHz band and
receives from 851-869 MHz. The radio is able to transmit
from 851-869 MHz for Talk-Around in the GE-MARC
system.
The Dual Format EDACS Monogram radio is offered
with several packages available with respect to the number
of systems/groups programmed and the EDACS feature set
allowed. The radio is also capable of Conventional
operation. The Radio is programmed using a Personal
Computer and an Interface Box connected to the UDC
connector on the top panel of the radio. This allows the
radio to be tailored to meet the requirements of the
individual user and of the System(s) it is operating within.
Figure 1 - Portable Radio
STANDARD RADIO FEATURES
Carrier Control Timer (CCT)
The CCT is programmable on a per channel basis and
prevents unnecessary channel traffic and radio damage if the
transmit timer is exceeded. If the programmed timer times
out during a transmission, the radio will beep and stop
transmitting. The beeping tone will continue until the
operator releases the PTT button.
Audio Alert Beeps
The radio generates a number of alert tones to indicate
various events.
Low Battery Alert
When the battery is low and needs to be recharged, the
B will displayed and a low pitch tone will sound every 130
seconds.
Power Up Self Test
Each time the radio is turned on it will perform a
power-up self test. After successful completion of the test,
an optional tone will sound and the current System and
Group/Channel will be displayed. If the unit does not pass
the self test, an error message will be displayed.
CONVENTIONAL FEATURES
Channel Guard provides a means of restricting calls to
specific radios through the use of a Continuous Tone Coded
Squelch System. (CTCSS), or a multi-code Digital Squelch
System (DCG). Tone frequencies range from 67 Hz to 210.7
Hz. There are 83 standard programmable digital codes.
Refer to Table 1 and Table 2.
Manual DTMF Operation
Telephone interconnect calls can be made using the 12-
button keypad. This keypad is enabled when a DTMF
programmed channel is selected and PTT button is pressed.

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Table 1 - Standard Tone Frequencies (Hz)
67.0 71.9 74.4 77.0 79.7 82.5 85.4 88.5 91.5 94.8 97.4
100.0 103.5 107.2 110.9 114.8 118.8 123.0 127.3 131.8 136.5 141.3
146.2 151.4 156.7 162.2 167.9 173.8 179.9 186.2 192.8 203.5 210.7
1. Do not use 179.9 Hz or 118.8 Hz in areas served by 60 Hz power distribution systems (or 100.0 Hz or 151.4 Hz in areas supplied with 50Hz power).
Hum modulation of co-channel stations may "false" Channel Guard decoders.
2. Do not use adjacent Channel Guard tone frequencies in systems employing multiple Channel Guard tones. Avoid same-areas co-channel use of
adjacent Channel Guard tones whenever possible. As stated in EIA Standard RS-220, there is a possibility of decoder falsing.
3. To minimize receiver turn-on time delay, especially in system using Channel Guard repeaters or receiver voting, choose the highest usable Channel
Guard tone frequency. Do not use tones below 100 Hz when it is necessary to meet the receiver response time requirements of EIA Standard RS-220.
Table 2 - Digital Channel Guard Tones
PRIMARY
CODE EQUIVALENT CODE PRIMARY CODE EQUIVALENT CODE PRIMARY CODE EQUIVALENT CODE
023 340 766 251 236 704 742 632 123 657
025 261 227 567 565 307 362
026 566 263 213 736 654 163 460 607
031 374 643 265 171 426 662 363 436 443 444
032 271 427 510 762 664 344 471 715
043 355 306 147 303 761 703 150 256
047 375 707 311 330 456 561 712 136 502
051 520 771 315 321 673 723 235 611 671
054 405 675 331 372 507 731 447 473 474 744
065 301 343 324 570 732 164 207
071 603 717 746 346 616 635 724 734 066
072 470 701 351 353 435 743 312 515 663
073 640 364 130 641 754 076 203
074 360 721 365 107 036 137
114 327 615 371 217 453 530 053
115 534 674 411 117 756 122 535
116 060 737 412 127 441 711 145 525
125 173 413 133 620 212 253
131 572 702 423 234 563 621 713 225 536
132 605 634 714 431 262 316 730 246 542 653
134 273 432 276 326 252 661
143 333 445 222 457 575 255 425
152 366 415 464 237 642 772 266 655
155 233 660 465 056 656 274 652
156 517 741 466 144 666 325 550 626
162 416 553 503 157 322 332 433 552
165 354 506 224 313 574 356 521
172 057 516 067 720 446 467 511 672
174 142 270 532 161 345 452 524 765
205 135 610 546 317 614 751 454 513 545 564
223 350 475 750 606 153 630 455 533 551
226 104 557 612 254 314 706 462 472 623 725
243 267 342 624 075 501 523 647 726
244 176 417 627 037 560 526 562 645
245 370 554 631 231 504 636 745
NOTE: Primary codes in bold are unique Ericsson codes.

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TRUNKED FEATURES (EDACS/GEMARC)
Preprogrammed DIG/DTMF Numbers
During the PC programming of the radio, the special
call list may be programmed with up to 96 numbers for
EDACS and 96 numbers for GE-MARC, depending upon
available personality space. Using the SPC key, the numbers
can be recalled to initiate the special call.
HOME
The radio will automatically select a desired Group
and/or System by depressing a single key.
Keypad Lock
To prevent undesired key presses, the keypad can be
locked at any time by depressing the LOCK key (shift RCL).
Power Up System/Group
The unit can be PC programmed to automatically select
a desired Group and/or System on power up.
Manual Individual Calls
The radio is capable of making Individual Calls which
are not programmed into your radio. The Individual Calls
are made by manually entering the ID number (EDACS) or
Tone Set (GE-MARC) from the radio keypad.
Manual Interconnect
The radio is capable of making Interconnect Calls
which are not programmed into your radio. The Interconnect
Calls are made by manually entering the telephone number
from the radio keypad.
Store
Individual and Interconnect numbers may be recalled
from a memory location and initiated using the Special Call
Key and RCL key.
Recall Last Number Send
When entering the Special Call mode the radio will
display the number (0-9) of the last accessed Special Call
number.
EDACS (ONLY) FEATURES
Group Scan
The radio monitors the control channel and responds to
all group channel assignments associated with the "scan"
list. The "Priority" group is dictated by the group currently
selected. If a call occurs on the "Priority" group while
monitoring one of the scan groups, the radio will
immediately enter into the "Priority" group.
Automatic Login
The radio automatically transmits the "Login" message
when the radio roams into a new system, when changing the
group selector and when the radio is tuned on. The "Login"
message includes the Logical ID and the Group ID for the
radio.
System/Group Selections
The standard EDACS feature set allows up to 16 groups
total, independent of number of systems programmed.
Optionally, the radio can be configured to provide 128
or more EDACS groups.
Conventional Failsoft
In the unlikely event of a trunking failure,
communications may take place in the Conventional Failsoft
mode. The radio will automatically be directed and will
switch to a communication channel set up for this purpose.
SCAT
The radio will operate in a Single Channel Autonomous
Trunking (SCAT) system.
Base/Mobile Operation
This pre-programmed option is used in some fleets so
units can only hear and talk to a base dispatch unit, not to
other radios in the group.
Priority System Scan (Optional)
A priority or "home" system is pre-programmed into the
radio. The radio unit continually searches (scans) for its
priority system and if found, locks onto it. This improves
network efficiency by preventing unnecessary multi sited
calls.

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Emergency (Optional)
An "Emergency" message is initiated by the caller and
automatically transmitted by the radio on the control
channel. The system automatically assigns the highest
priority to the talk group.
Wide Area Scan (Optional)
When the radio unit loses the control channel of the
current system, the radio automatically begins searching for
a new control channel. The intelligent search algorithm uses
a pre-programmed map of adjacent systems to ensure
minimum transition time.
Dynamic Regrouping (Optional)
The unit is capable of being reprogrammed over the air
while the radio is still active. Multiple talk groups can be
added to a radio unit or optionally, the radio can be forced
to communicate on designated talk groups.
GE-MARC (ONLY) FEATURES
Talk-Around (Direct Mode)
The radio is capable of direct unit-to-unit short range
communication link. It is intended to maintain
communications outside the coverage area.
SYSTEM DESCRIPTION
EDACS
The radio operates in either EDACS (digital) mode, or
in GE-MARC (tone) mode, providing customers another
dimension of flexibility in operation. Both modes provide
opportunities to increase RF channel utilization through
faster channel access and the privacy inherent with selective
signalling.
The EDACS system uses 9600 baud, high speed, digital
signalling to identify individual units, user groups, fleets,
and agencies. Agencies contain multiple fleets and fleets
contain multiple user groups (sub-fleets). By using this
addressing scheme, large user groups can be accessed
simultaneously all the way down to individual users. The
programming to determine transmit encoded groups and
decoded received groups is contained in the personality
EEPROM of the mobile. This information is individually
programmed to suit each users needs via the PC programmer
for the radio.
The typical system configuration consists of at least 2
repeater stations (with a maximum number of 25) and the
associated mobiles and portables. One repeater always is a
control channel dedicated to sending out continuous control
data and also to receive channel request data from the
mobiles and portables. When a radio is first turned on, it
scans the available list of frequencies programmed in the
personality EEPROM for a control channel. When a control
channel is found, the radio locks on to the frequency and
monitors the data for a channel assignment (incoming call).
When receiving a channel assignment (incoming call),
the monitoring radio immediately switches over to the
assigned voice channel and waits for a high speed data
confirmation message. Upon receipt of this message, the
voice paths are unmuted and the user can hear the call.
While on the voice channel, the radio also continuously
monitors the low speed, 150 baud (subaudible) data and
carrier noise squelch to ensure consistent operation. Upon
loss of subaudible data reception (i.e., deep fade, or out-of-
range), the radio returns to the control channel frequency.
To initiate a call, the user keys the radio (which is
locked to the control channel), and a 30 millisecond high
speed data slotted channel request is transmitted to the
control channel receiver. The control channel processes the
request from the radio and transmits back a voice channel
assignment on an unused channel.
When all available voice channels are in use, the control
channel places the radio into a queue, transmits a queue
message back to the radio, and will give a channel
assignment to the requesting radio as soon as a voice
channel is free. If the system is busy and the station queue is
filled to capacity, a system busy message is returned to the
requesting radio and an alert signal is given to the user.
After the initiating radio receives a channel assignment
from the control station, it immediately switches frequency
over to the assigned voice channel and sends a burst of 9600
baud dotting. The microphone voice paths are then unmuted
and the transmission begins. The transmitting radio also
continuously sends out a subaudible tone (along with voice)
for system reliability. If the station loses this signalling, the
voice channel is muted and all receiving radios are sent back
to the control channel.
In normal operation, the transmitting radio sends a high
speed data burst to indicate that the user has unkeyed,
causing all listening radio to switch back to the control
channel.

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CONVENTIONAL MODE
In conventional mode (not trunked) the radio can
operate either with tone Channel Guard, digital Channel
Guard, or carrier squelch, depending on personality
programming. Tone Channel Guard range is 67.0 to 210.7
Hz. Squelch Tail Elimination (STE) is used with Channel
Guard to eliminate squelch tails at the receiving radio by
phase shifting the transmitted Channel Guard tone when the
PTT is released.
Direct mode works identically to conventional mode
except that the transmit frequency band is changed to 851 to
870 MHz to permit direct radio -to- radio communications.
GE-MARC
The GE-MARC trunked radio system consists of a
repeater for each channel and the users' radio units. The
system uses tone signalling with each radio being assigned
two and/or four tone group tone sequences. Groups of radios
are assigned the same tones so that any unit can talk to all
other units in the same group. A block diagram of the GE-
MARC is shown in Figure 2.
When originating a call, the radio identifies an idle
repeater channel and interrogates it with a single burst of
"busy" tone; the repeater keys its transmitter and sends a
burst of "acquisition" tone back to the radio unit. When the
interrogating radio detects the acquisition tone, it then
transmits its collect and group tones which the repeater
regenerates for all idle radio units in the system.
The idle radio, which continually scans all channels,
will stop on the active channel if any of the programmed
collect tones are detected and wait for group tone(s).
If the correct tone sequence is detected, the radios will
alert the operator of an incoming call and open their audio
circuits. If the correct sequence is not detected, the idle
radios will resume scanning the channels. Once the radio is
"locked" on a channel, it will remain there until the repeater
times out or the operator terminates the call.
Figure 2 - GE-MARC Block Diagram

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Operational Modes
The radio will always be in one of three operational
modes: Idle, Wait, or Ready. The three operational modes
and the conditions that cause the radio to switch from one
mode to another are shown in Figure 3.
The radio enters the Idle mode when power is turned on
and begins scanning channels for incoming calls. The Wait
mode is entered when the user places a call. The radio
remains in the Wait mode until a channel is acquired, or if
no channel is available. The Ready or Conversation mode is
indicated by an alert tone and the mode indicator on the
control panel. A signal timing diagram is shown in Figure 4.
Idle Mode
When the radio is in the Idle mode, the audio is muted
and all channels programmed for call decode are
sequentially scanned for an incoming call. An incoming call
is identified by detecting one of the collect tones
programmed in the area. Upon receipt of a collect tone, the
radio looks for a short interval for the group or individual
tones providing that their collect tones are the same. When
no valid tone is found, the mobile will resume scanning the
channels for an incoming call.
If a group (or individual decode) tone is detected, the
radio then looks for busy tone for a 90 millisecond period. If
four tones are properly decoded, the radio will then look for
busy tone for 270 milliseconds.
When no valid tones are found, the radio will resume
scanning for a call with the next channel. When a busy tone
is found, the radio will enter the Ready mode. If busy tone is
not detected, the radio remains in the Idle mode and
continues scanning channels looking for an incoming call.
Pressing the PTT switch will cause the radio to enter the
Wait mode.
Wait Mode
When the user enters the Wait mode, the display group
is checked to make sure it is a valid call-originate group. If it
is not valid, a low-frequency tone is heard for one second. If
valid, the radio will scan the call-originate frequencies for
brief intervals until it finds one with no busy tone on it. If no
channel is free, the radio, if programmed for this option, will
activate the Call Retry state and display "RETRYNG" in
the display. Retrying will cause the radio to revert to the Idle
mode and scan for an incoming call while trying to acquire a
free repeater approximately every 5 seconds for a 2 minute
period. If the Retry option is not enabled, the radio will
sound the low-frequency tone and then return to the Idle
mode and display "BUSY".
If a channel with no busy tone is found, the radio
transmits a burst of busy tone to acquire the repeater. The
repeater then responds with a burst of acquisition tone.
Upon receipt of the acquisition tone, the radio proceeds to
transmit the group tones (either two or four tones). If a four-
tone sequence is sent, the radio must detect all four tones
and busy tone before entering the Ready mode. If a two-tone
sequence is sent, the busy tone must be present within 90
milliseconds of the last tone in order for the radio to enter
the Ready mode. If no busy tone is present or if the four-
tone sequence isn't valid, the mobile will jump to the next
channel in the call originate set and check for busy tone as
described above.
Ready Mode
When an incoming call has been detected or an idle
channel has been acquired, the mobile enters the Ready
mode. In this mode, the audio and push-to-talk circuits are
enabled, the speaker is unmuted, and the operator is alerted
by an alert tone. The radio can then be used in the
conventional push-to-talk manner with the radio remaining
on the channel until the operator hangs up or the repeater
drops the busy tone causing the unit to revert to Idle mode.
If a call is initiated and a sequence of five beeps is
sounded, the user cannot access the radio system because
the radio is out of receive range or is inoperative. Any
subsequent call will be ignored for 20 seconds.
NOTE
Figure 3 - GE-MARC Operation Modes

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Figure 4 - Signal Timing
GLOSSARY OF GE-MARC TERMS
Idle Mode
In the "standby" condition, the mobile is inactive but
prepared to call or be called. The trunked radios are IDLE
until they are turned off.
Wait Mode
In the "attempting origination" condition, the Wait
mode is entered from Idle mode (only) as the user presses
the PTT switch on the microphone. If successful, the unit
becomes READY. Otherwise, the unit is IDLE or
IDLE/WAIT after all channels are tried.
Ready Mode
In the "operating" condition, Ready is entered from Idle
mode via Wait mode when calling or directly from Idle
when called. Ready mode ends (the radio reverts to Idle)
when the user disconnects or with the loss of received Busy
Tone from the repeater. This normally occurs when the
repeater shuts down after communication is completed.
Busy Tone
A "Voice-plus" tone of 3051.9 Hz is the standard busy
tone. The 2918 Hz is the alternate busy tone. The busy tone
modulates radio and repeater transmitters at a low level of 1
kHz deviation continuously. This tone is filtered out of the
received audio and is used to hold the communication
channel active. It also excludes other radios from using the
channel when a call is active.
Acquisition Tone
A 1962.9 Hz tone sent at full deviation for 50
milliseconds from the repeater is used as acknowledgment
from the repeater that a busy tone was sent and signals the
radio that signalling tones can now be sent.
Collect Tone
A tone chosen from 34 standardized frequencies,
ranging from 508.6 Hz to 2792.4 Hz, is used as the first tone
in the group tone sequence. The collect tone is used to
gather all radios with the same collect tone for decoding a
call. The duration of the tone varies as a function of the
number of channels which are programmed into the radio
and/or repeater.
In a two-tone call, the radio sends the collected tone for
a programmable duration. In the four-tone call, the radio
always sends a 90-millisecond collect tone which the
repeater regenerates and sends for the correct duration.

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Group/Individual Tones
Group/Individual Tones chosen from the 34 standard
frequencies follow the collect tone. In a two-tone call, the
second tone is sent for 450 milliseconds. In a four-tone call,
the second, third, and fourth tones are sent for 90
milliseconds from the radio and 180 milliseconds from the
repeater.
RADIO OPERATION
A complete set of operating instructions for EDACS
Monogram Portable Radio are provided in AE/LZT 123
1875 and are provided with each radio.
This radio is flexible in operation and can be used in
any of three operating modes: Conventional radio system,
Enhanced Digital Access Communications (EDACS)
system, or GE-MARC (tone controlled) system. Either of the
latter two systems provide trunked channel selection for
increased channel utilization.
In an EDACS trunked environment, the user selects a
communications system and group. In this mode, audio
channel selection is transparent to the user and is controlled
via digital communication with the system controller. This
mode incorporates advanced programmable features and fast
access to communication channels.
In a GE-MARC trunked environment, the user selects a
communications area and group. In this mode, audio channel
selection is also transparent to the user and is controlled via
tone signalling.
In Conventional mode, the user selects a channel and
communicates on that channel. In this mode, a system refers
to a set of channels and a channel is a transmit/receive radio
frequency pair.
The exact operation of any radio depends upon the
operating mode, the programming of the radio and the
particular radio system. Most features described in these
operating instructions can be enabled or disabled through
programming. Both of these important factors must be
considered.
USER INTERFACE
Operating controls are located on the radio top and
front panel and microphone.
The front panel LCD provides radio status and
communication control information to the operator. The
keypad is used for manual number entry for individual calls
access to a telephone interconnect system and activation of
various EDACS, GE-MARC, and conventional features.
Turning The Radio ON/OFF
The radio is turned on by rotating the
ON/OFF/VOLUME control clockwise from the OFF detent
position. After the radio has passed the power-up self test,
an optional tone will sound and the current System and
Group will be displayed. If the unit does not pass the test,
an error message will be displayed (see ERROR
MESSAGES section) or the display will be blank.
ALERT TONES
The radio generates a set of unique alert tones to
indicate operating status. The following section identifies
and describes the alert tones for Conventional, GE-MARC,
and EDACS applications.
EDACS APPLICATIONS
CALL
ORIGINATE
ALERT
If programmed, a short tone is sounded
whenever the Push-To-Talk key is
pressed and the radio has acquired a
channel. This tone indicates the user can
begin communications.
CALL
QUEUED If one short, high-pitched tone sounds after the transmitter is keyed, this
indicates that the system has placed the
request in a queue. This tone sounds at
both the transmitting unit and the
receiving unit(s) indicating to the user on
the receiving end that a call is being
directed to them. If the PTT is unkeyed
while in the queue, the radio autokeys
(automatically keys) Push-To-Talk when
a channel becomes available (see
AUTOKEY).
AUTOKEY When the PTT is keyed to place a call on
the system, but the PTT is released
before getting to the channel (e.g. a
queued call), the radio automatically
keys on the channel when it gets the
assignment. The radio generates a long
beep and holds the transmitter keyed for
two seconds. Pressing the PTT button
keeps the channel and sends the message
before this two second time-out has
expired.

AE/LZB 119 1647 R1A
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SYSTEM BUSY If you press the PTT key and hear three
short, medium-pitched tones, this
indicates that the receiving party is
already on the system or the system is
busy and its queue is full. You must
rekey later to access the system.
CALL DENIED A single, low-pitched beep sounds when
the PTT key is pressed and the request
is denied by the system. This happens if
the unit is an invalid user or if the unit
is requesting an unavailable service.
OUT-OF-
RANGE/
SYSTEM
INOPERATIVE
A single, low-pitched tone sounds
immediately after the PTT key is
pressed indicating the radio is out of
range of the repeater. The radio tries to
place the call for a short period (3
seconds) after the initial attempt. The
radio generates a second low-pitched
tone when it gives up trying to place the
call. These tones are also heard if the
system is off the air or the radio needs
servicing (even when the radio is within
calling range of the repeater).
GE-MARC APPLICATIONS
CALL
RECEIVED
ALERT
If programmed, a single alert tone
sounds when a group call is received
and a two-tone alert (one high followed
by one low tone) sounds for an
individual call.
CALL
ORIGINATE
ALERT
WAIT momentarily displays when a
call is being placed. Then a three-tone
alert is sounded to indicate the call
origination is complete. This indicates a
channel was acquired and is ready for
normal conversation.
INVALID CALL
ORIGINATE
ALERT
A low-frequency tone is sounded for
one second immediately after pressing
PTT and the display does not show
WAIT. This indicates a call was
attempted within a group that is not
enabled for call originate or an invalid
dispatch overdial call was attempted.
SYSTEM
TONES A low-frequency tone is sounded for one second after attempting to place a
trunked call and BUSY is displayed.
This indicates that the GE-MARC
system is busy. If the "Call Retry"
option has been enabled through
programming, the radio retries at 5
second intervals up to 15 times unless
END is pressed, a channel is acquired,
or an out-of-range condition occurs.
OUT-OF-
RANGE ALERT If NO SVC is displayed and five beeps
are sounded after attempting to place a
trunked call, the radio is out of range of
the GE-MARC system. If the beeps
sound when the radio is within known
range of the system, the radio may need
servicing. If the "Call Retry" is active,
the radio tries the channel at twenty
second intervals for five minutes.
CARRIER
CONTROL
TIMER
(GE-MARC and Conventional
operation.) A pulsed-tone signal is
sounded for a pre-programmed time
after PTT is pressed. After nine seconds
of pulsing the alert tone, the radio
unkeys the transmitter and
communications are interrupted. While
the tone is pulsing, the user can release
and press PTT again to reset the timer
and resume the conversation. In the
conventional mode, the radio unkeys
and beeps until PTT is released.
SYSTEM
TONES The GE MARC radio may generate other system tones to alert the user of
custom programmed events. Contact the
GE-MARC system operator for details
about these alert tones.
ERROR MESSAGES
SYN LOC: if at anytime the Synthesizer is unable to
load and lock on the channel property, a SYN LOC message
will be displayed. If the SYN LOC message is displayed on
all systems, the radio has failed or has not been programmed
properly. The radio’s buttons and keys will still operate
with a SYN LOC message displayed.
PRS ERR: message indicates the personality has not
bee programmed into the radio.

AE/LZB119 1647 R1A
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KEYPAD LOCK
The keypad can be locked at any time to prevent
undesired key presses. To lock the keypad when it is in the
unlocked state, press and release the LOCK (shifted r )
key. All buttons and keys except the PTT, H ,
SHIFT/CLR/MONITOR and LOCK (shifted
r ) will
not be inhibited. If the Emergency function of the H key
is disabled, the H key will also be inhibited. If the key is
programmed for Emergency or Emergency/Home, then the
key is not inhibited and an emergency can still be declared
on the Home System/Group or the current System/Group
(however programmed). To unlock the keypad when it is in
the locked state, press and release the LOCK (Shifted r )
key.
RF BOARD
THEORY OF OPERATION
650-020-0002
DESCRIPTION
RF Board 650-020-0002 consists of a receiver,
transmitter, synthesizer circuitry, VCO module, and a
TCXO module. The RF Board mounts to the bottom of the
radio’s chassis. Connectors on the board interconnect the
RF Board to the Digital Board. The RF Board contains the
following major components:
• 1.1 GHz PLL Frequency Synthesizer
• GE-MARC Busy Tone Detect Frequency
Synthesizer
• 805-870 MHz 2-watt Power Amplifier
• Antenna Switch
• Low Power Narrow Band FM IF Chip
• 12.8 MHz +/- 1.5 ppm TCXO Module
• 805-870 MHz VCO Module
CIRCUIT ANALYSIS
RECEIVER SECTION
The radio receiver section consists of a double
conversion super-heterodyne type receiver which uses a 1st
IF frequency of 45.3 MHz and a 2nd IF frequency of 455
kHz. The features of the receiver are as follows:
• Non-tuneable pre-selector and post-selector.
• 4-pole crystal filters in the 1st IF gives increased
suppression of spurious received signals such as
first and second IF images.
• Two 4-pole Gaussian filters in the second IF for
improved data recovery.
RF Amplifier and 1st Mixer
The received signal from the antenna is passed through
the antenna switching module, U102, to the receiver
circuitry when 0 Vdc is applied to U102 pin 4. This signal
is then applied to F101. This bandpass filter prevents
undesired signals from passing through the front-end of the
receiver because it is centered at 860 MHz and has a
passband 20 MHz wide. Any signal passing F101 will be
amplified by approximately 12 dB by Q101and pass through
F102. This is to decrease the 1st IF image and to prevent
saturation of the mixer, Q103, by signals other than the
preferred frequency. In addition, F101 and F102 minimize
1st L.O. leakage radiation through the antenna.
Q102 is a current source that supplies Q101 with 4 mA.
Any signal that passes F102 is applied to the base of Q103.
The signal is mixed with the 1st L.O. signal to generate the
first IF frequency of 45.3 MHz. The 1st L.O. signal is
applied to Q103's emitter through C133. The strip line
connected to Q103's emitter maintains high impedance in
order to impedance match into the mixer.
1st IF Filter and Amplifier
The signal that has been converted to the 1st IF
frequency of 45.3 MHz by the mixer is impedance matched
through L101, C107, and C108. This signal is applied to the
3rd overtone crystal filter (F103, F104) that has a center
frequency of 45.3 MHz. The bandwidth of this filter is +/-
7.5 kHz. This will reduce the image of the 2nd IF and other
undesired signals. The signal is impedance matched out of
the crystal filter through L103, C110, C111 and applied to
the 1st IF amplifier (Q104). Q104 will amplify the first IF
signal by approximately 20 dB.

AE/LZB 119 1647 R1A
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2nd Mixer and Detector
The received IF signal of 45.3 MHz is supplied to the
2nd mixer via U101 pin 16. Here it is mixed with the 2nd
L.O. signal of 45.755 MHz and converted to the 2nd IF
frequency of 455kHz. This 2nd IF frequency is passed
through ceramic filters F105, F106 where it is limited and
passed to the quad detector. The recovered audio signal is
then present on U101 pin 9. This audio is buffered by the
emitter-follower stage Q106 and sent to the Digital Board
for further processing. The second L.O. signal is generated
by crystal X101. This crystal is a 45.755 MHz, 3rd
overtone, series mode crystal.
TRANSMITTER SECTION
Synthesizer Switching and Buffering
The VCO output signal is amplified and buffered by
Q108 and switched between the TX or RX path by D101.
When in TX, 7.5 Vdc (TX Power), is applied to R136. This
turns D101 on and allows the signal to pass to amplifier
Q110 and on to power module U103. The input level to
U103 is 0 dBm.
Power Module and Antenna Switching Module
When the radio is in the TX mode, 7.5 Vdc (TX Power)
is applied to power module U103 pin 2.
The signal from the VCO output is amplified by
approximately 33 dB, and is supplied to U102 antenna
switching module through the forward power detector. TX
Power is also applied to U102 pin 4 causing the path from
the antenna connector to the RX circuit to be disconnected,
and the TX power path from U103 to the antenna to be
connected.
Forward Power Detector and APC
The radio maintains stable output power of 2.0 watts by
forward power detection and APC circuitry. The forward
power is detected from R149, R150, and a strip line. This is
rectified by D102 and filtered by C148. The filtered voltage
will be directly related to forward power and is applied to
the non-inverting input of U104.B. The DC voltage is
doubled in this stage and then compared to a preset DAC
value by U104.A. The output form U104.A is applied to the
Class A stage of U103 pin 1. The voltage on this pin is
directly proportional to the RF output power of amplifier
U103. This completes a negative feedback loop which
results in a constant RF output power over power supply
voltage range and temperature variances. The preset DAC
value is set for an RF output level of approximately 1.5
watts at the time of manufacture.
PLL CIRCUIT DESCRIPTION
VCO and Buffer Amplifier
The VCO generates frequencies of 806-824 MHz in
normal RX and TX trunking modes and 851-869 MHz in
talk-around mode. The VCO is a major block of the phase
lock loop and is controlled by PLL IC U105 to maintain a
stable frequency.
Q302 is the active device of the Colpitts type VCO.
Fixed capacitors C307, C308, and C309 provide the
feedback required to sustain oscillation. Ceramic resonator
CF301 is a low characteristic impedance transmission line
shorted at one end. Due to its electrical length and its
termination, CF301 acts as a high Q inductor for the VCO
resonant circuit. CR301, in series with padding capacitor
C305, varies the circuit capacitance and tunes the oscillator
to the desired frequency. The varactor (CR301) is DC
controlled from the PD (phase detector) output of the
synthesizer. TC301 is a tuning voltage adjustment that
compensates for slight differences in circuit capacitance.
CR302, in series with C304, is the modulation circuit of
the VCO. The audio modulation signal is applied to voltage
divider R304-R305 to control the amplitude. The attenuator
audio is applies via R403 to the varactor cathode.
R308 samples a small portion of the VCO RF and
couples it through C310 to the base of Q303. Q303 is the
input section of a cascode amplifier stage. The main
purpose of a cascode amplifier is to provide isolation. The
cascode output section (Q108) is located on the RF board.
This RF from Q108 is applied to the synthesizer for phase
locking and to the RX-TX switching circuit for use as L.O.
injection or transmitter drive. The VCO output level of -12
dBm is applied to Q108, is amplified to +3 dBm at Q109
and applied to the PLL IC through C141 for phase locking.
In normal RX-TX trunking, C303 is part of the resonant
circuit tuning. For trunking frequencies, the T/A (talk-
around) pin is high turning on Q301. In turn PIN diode
D301 is forward biased by R302 and this effectively AC
grounds C303. When T/A is logic low, PIN diode D301 is
off and C303 is removed from the circuit so the VCO can
run at the higher transmit talk-around frequencies.

AE/LZB119 1647 R1A
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PLL IC (U105) AND LOOP FILTER
The frequency synthesizer consists of a single loop
phase locking circuit with a reference frequency of 12.5
kHz. The phase-locked loop operates as follows. The
MC145190 has on-board 64/65 prescalers that divide the
VCO frequency to a useable value. In addition the ‘190 has
3 counter registers that are controlled by the microprocessor
via U105 pins 17-20. These registers are the R,N, and A
registers. To obtain the 12.5 kHz reference frequency, 1024
must be loaded from the microprocessor to the R-register.
This is the TCXO frequency (12.8 MHz) divided by the
reference frequency (12.5 kHz).
The frequency correction signal is determined by the
PLL IC in the following manner. The divide ratio of the
prescaler is initially 65 and the A and N registers are set to a
start value. The Synthesizer chip will count the cycles given
by the prescaler by decrementing the value in the A and N
registers by one for each cycle. When the A register equals
zero, the prescalers divide ratio changes to 64. The
MC145190 will continue to count until the N register is
zero, then the A and N registers are reloaded with their
starting values. This process is then repeated. The total
divide ratio of the prescaler and the A and N registers can be
expressed by K={128 (N-A)}+129A. This can be simplified
to K=128N + A. After the VCO frequency is divided by the
total divide ratio (K), it is compared with the reference
frequency and a phase error signal is generated. To
determine the VCO frequency, multiply the reference by the
divide ratio. FVCO= FREF x K.
The phase error signal, output at U106 pin 6 (PDOUT),
is converted from PDOUT current to a correction voltage by
the loop filter. This filter has a low-pass response with a
cutoff frequency of approximately 194 Hz. The filter
consists of C128, C154, C155, C156, and R128, R157. The
first section of the loop filter (C155, C156, and R157)
determine the transient response of the filter, convert
PDOUT current into a corretion voltage, and have a large
impact on reference sideband levels. The saturation
capacitor (C154) is responsible for keeping transient
voltages on PDOUT within linear operating range of the
charge pump and for additional sideband suppression. The
final section (R128 and C128) is used for extra sideband
filtering without affecting the transient response of the filter.
Lock Detector
When the synthesizer is locked, the output at U106 pin
2 is essentially at a high level with narrow low-going pulses.
This signal is filtered by C158, C159, and R158.
When the synthesizer is unlocked, the output at U105
pin 2 is essentially at a low level. When the PLL Synthesizer
is in the unlock state, the microprocessor performs an unlock
recover routine. If the recovery fails, all operations of the
radio stop and “SYNLOC” is shown on the LCD.
Power Switching and Voltage Regulator
U109 and U110 provide a regulated +5Vdc to the RF
Board. U110 provides power to the receiver section of the
board. U109 supplies power to the rest of the board
including the synthesizer chip, the VCO module, and the
TCXO module. The use of two regulators provides
protection from interference between the receiver and the
other circuitry.
DIGITAL BOARD
THEORY OF OPERATION
650-010-0003
Digital Board 650-010-0003 contains microprocessor
circuitry used to control the radio's RF circuits and display
board circuits. In addition this board provides dual mode
trunking control and performs transmit-receive signal
processing. Physically the Digital Board mounts on the top
of the frame assembly. Connectors on the board
interconnect the RF board and the display board. The
Digital Board contains the following major components.
• 8- bit micro controller
• 128k x 8-bit operational software memory (flash
EEPROM)
• 4800/9600 baud modem
• serial number memory (ROM)
• audio signal processor, busy tone notch filter
• 8K x 8-bit CMOS static RAM
• 5-Volt regulator, and Audio Power Amplifier
CIRCUIT ANALYSIS
MICRO CONTROLLER U701
Micro controller U701 controls the operation of the
radio. This integrated Circuit is an Intel 83C51 8-bit micro
controller with extensive I/O (input/output) interface and
controlling capabilities. The micro controller performs the
following radio functions.
• EDACS trunking functions