Ericsson LBI-38848D User Manual

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Page 1

LBI-38848D

PARTS LIST

Maintenance Manual

DUAL FORMAT MDX

806 - 870 MHz MOBILE RADIO



DUAL FORMAT MDX RADIO ASSEMBLY

SYMBOL PART NUMBER DESCRIPTION

APPLICATION ASSEMBLY 19D904183

— — — — ASSEMBLIES — — — A1 19D902123G22 RF BOARD

A3 19D901891G2 SYSTEM BOARD A4 19D904025G2 AUDIO AMPLIFIER BOARD A5 19D903963G1 AUDIO/LOGIC BOARD 19C851822G1 PA BOARD

— — — — — KITS — — — — — 344A4253G1 Hardware Kit (No. 1)

344A4255G7 Hardware Kit (No. 2) — — — — — CABLES — — — — 19A705301P6 Cable, Antenna

19B801467P1 Cable, J705 to J151 19B801467P2 Cable, J5 to J105 19B801454P36 Cable, RX to J104 19A705235P3 Cable, Ribbon, J901 on Audio Amplifier

to J902 on System Board 19B801454P38 Cable, Antenna to J7 19B801454P37 Cable, TX to J101 19B802397P1 Cable, Handset

— — — MISCELLANEOUS — — 19D904027P1 Casting

19C337683G2 Bracket 19D904185G1 Cover, Bottom 19D904186G1 Cover, Top 19D904187G1 Panel, Front 19B801358P18 Cable, 9 Foot, Power 19B235310P10 Nameplate, Combination

ISSUE 1

ericssonz

TABLE OF CONTENTS

RF BOARD . . . . . . . . . . . . . . . . . LBI-38849

SYSTEM BOARD . . . . . . . . . . . . . LBI-38842

AUDIO/LOGIC BOARD . . . . . . . . . . LBI-38843

AUDIO AMPLIFIER BOARD . . . . . . . LBI-38844

FRONT CAP ASSEMBLY . . . . . . . . . LBI-38850

LBI-38974

PA BOARD . . . . . . . . . . . . . . . . . LBI-38302

SERVICE SECTION . . . . . . . . . . . . LBI-38851

COMPONENTS, ADDED, DELETED OR CHANGED BY PRODUCTION CHANGES

Ericsson Inc.

Private Radio Systems Mountain V iew Road Lynchb ur g, Virginia 24502 1-800-528-7711 (Outside USA, 804-528-7711) Printed in U.S.A.

Page 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The software contained in this device is copyrighted by the Ericsson Inc. Unpublished rights are reserved under the copyright laws of the United States.

LBI-38848D

TABLE OF CONTENTS

Page

SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

RF BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

S y nthesizer Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Transmi t Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Receiver Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

POWER AMPLIFIER BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

AUDIO/LO GIC BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

SYSTEM BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

FRONT CAP ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

ACCESSORIES AND OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

PC PROGRAMMER OPTI ONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

PC PROGRAMMED OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Carrier Control Timer (CCT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Channel Guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

S q uelch Tail Elimination (STE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Retry Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

HARDWARE AND HARDWARE OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

OPTION CABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

NOISE SUPPRESSION KIT OPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

POWER CA BLE OPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

EXTERNAL SPEAKER OPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

EXTERNAL ALARM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

SYSTEM DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

EDACS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

CONVENTIONAL MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

GE-MARC V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Operational Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Idle Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Ready Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

GLOSSARY OF GE-MAR C V SYSTEM TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

RADIO OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

USER INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

ALERT TONES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

EDACS APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

GE-MARC APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

ASSEMBLY DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

INTERCONNECT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Back

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 c hanges will be incorporated into ne w 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.

Page 3

LBI-38848D

SPECIFICATIONS*

GENERAL

Regulatory Approval

FCC (United States) AXATR-311-A2 DOC (Canada) TR-311

Operating Voltage 13.8 Volts ±20% Battery Drain

Receiver (13.8 Vdc)

Off 0.01 Amperes (maximum) Squelched 0.75 Amperes (maximum) Unsquelched 2.0 Amperes (maximum at 10 Watts audio,

External Speaker)

Transmitter (13.8 Vdc) 11 Amperes (maximum at 25 Watts RF)

Channel Spacing 25 kHz (12.5 kHz NPSPAC) Frequency Stability ±1.5 PPM (±0.00015%)

Temperature Range -30C to +60C (-22F to +140F) Dimensions (H x W x D)

(Less Accessories) Height 5.3 cm (2.1 inches) Width 18.2 cm (7.2 inches)

Depth 24.0 cm (9.5 inches) Weight 3.0 kg (6.6 pounds) Antenna Impedance 50 Ohms

TRANSMITTER

Frequency Range 806.0125-824.9875 MHz Output Power 25 Watts (Intermittent duty cycle; EIA 20%) Audio Sensitivity 125 mVrms (typical) Spurious and Harmonics <-16 dBm Audio Distortion 5% maximum Modulation Limiting +5 kHz maximum (4 kHz max 821.000 - 824.9875 and

866.000 - 869.9875 MHz) FM Hum and Noise -45 dB Audio Frequency Response Within +1, -3 dB of a 6 dB/octave pre-emphasis curve

Per EIA Standards from 300-3000 Hz

RECEIVER

Frequency Range 851.0125-869.9875 MHz Acceptable Frequency Displacement ±2.5 kHz minimum

Sensitivity (12 dB SINAD) -113 dBm minimum Spurious Response 70 dB minimum

Adjacent Channel Selectivity 68 dB minimum at ±25.0 kHz Intermodulation Distortion 65 dB minimum Audio Frequency Response Within +2, -8dB of a 6 dB/octave de-emphasis curve

from 300 -2700 Hz Audio Output 10 Watts (External Speaker); 4 Watts (Internal Speaker) Audio Distortion 5% maximum at 1 kHz

These specifications are intended primarily for use by se rvice personnel. Refer to the a ppropriate Specification Sheet

for complete specifications.

GENERAL DESCRIPTION

The Dual Format MDX Mobile Radio is a synthesized,

wideband radio that uses integrated circuits and microcomputer technology to provide high performance trunked operation. This radio operates in the Enhanced Digital Access Communications System (EDA CS vironments and in conventional communications systems. The radio provides 2 5 Watts of RF power output in th e 80 6.0125 -

824.9875 MH z and 851.0125-869 .9875 MHz bands. The receiver operates in the 851.0125-869.9875 MHz band.

All radio functions are stored in a programmable Electrically Erasable grammable using an IBM compatible personal computer with the following equipment:

Serial Program mi ng Interface Modu l e TQ3370

•

Programming Cable (19B801417P10) TQ3372

•

MDX Series Programming

•

Software (EDACS) TQ3373 MDX Series Programming

•

Software (GE-MARC only) TQ3346

With the interface equipment and software, the computer can be used to program (or re-program) customer system frequencies, Channel Guard tones and options. Selection of options is done during radio initialization using the PC programmer.

The Dual Format MDX Mobile Radio assembly contains the following circuit boards and assemblies:

Power Amplifier Boar d 19C851822G1

•

RF Board 19D902123G22

•

System Board 19D901891G2

•

Audio/Logic Board 19D903963G1

•

Audio Amplifier Board 19D904025G2

•

Front Cap Assembl y 19D904151G1

•

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-are as co-channel use of adjacent Channel Guard tones whenever possible. As stated in EIA Standard RS-220, there is a possibility of decoder fal sing.

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.

PROM (EEPROM

), GE-MARC trunking en-

). The radio is field pro-

Table 1 - Standard Tone Frequencies (Hz)

The circuit boards are all mounted on a main casting to provide easy access for servicin g. Interc on nect plu gs ar e used to connect the boards to eliminate pinched wires and other wiring problems.

RF BOARD

The RF Board incl ud es t he programmabl e frequency s ynthesizer, transmitter exciter , recei ver front end and IF circuitry .

Synthesizer

The synthesizer circuit generates all transmit and receive RF frequenci es. The sy nthesiz er fre quenc y is contr olled by t he microproces s or located on the Au di o/Logic Board. F r equency stability is maintained by a temperature compensated reference oscillator module. Transmit audio is processed on the Audio/Logic Board and applied to the synthesizer to modulate the VCO and TCXO. The buf fered VCO output dri ves b oth the transmitter exciter and the receiver mixer.

Transmitter

The transmitter consists of a fixed-tuned exciter module, a PA module and a power control circuit. The PA module provides RF output to drive the antenna. The power control circuit controls the PA module to maintain a constant output power across the band. The RF output le vel is internally adjustable for rated power. Thermistors in the control circuit protect the PA from overheating by reducing the power output level.

Receiver

The dual conv ersion recei ver circuit consists of a front end section, 45.3 MHz first IF, a 455 kHz second IF, and FM detector. All audio processing and squelch functions are accomplished on th e Au di o Board.

POWER AMPLIFIER BOARD

The PA board (19C851822G1) amplifies the RF board output then connects it back to the RF board where it is coupled through a PIN diode antenna switch, the low-pass filter and the directional coupler to provide 25 watts power output at the antenna conn ect or.

Page 4

LBI-38848D

Table 2 - Digital Channel Guard Codes

PRIMARY CODE

023 025 026 031 032 043 047 051 054 065 071 072 073 074 114 115 116 125 131 132 134 143 152 155 156 162 165 172 174 205 223 226 243 244 245

NOTE: Primary codes in bold are unique Ericsson codes.

EQUIVALENT CODE

340 766 566

374 643 355

375 707 520 771 405 675 301 603 717 746 470 701 640 360 721 327 615 534 674 060 737 173 572 702 605 634 714 273 333 366 415 233 660 517 741 416 553 354 057 142 270 135 610 350 475 750 104 557 267 342 176 417 370 554

PRIMARY CODE

251 261 263 265 271 306 311 315 331 343 346 351 364 365 371 411 412 413 423 431 432 445 464 465 466 503 506 516 532 546 606 612 624 627 631

EQUIVALENT CODE

236 704 742 227 567 213 736 171 426 427 510 762 147 303 761 330 456 561 321 673 372 507 324 570 616 635 724 353 435 130 641 107 217 453 530 117 756 127 441 711 133 620 234 563 621 713 262 316 730 276 326 222 457 575 237 642 772 056 656 144 666 157 322 224 313 574 067 720 161 345 317 614 751 153 630 254 314 706 075 501 037 560 231 504 636 745

PRIMARY CODE

632 565 654 662 664 703 712 723 731 732 734 743 754

036 053 122 145 212 225 246 252 255 266 274 325 332 356 446 452 454 455 462 523 526

EQUIVALENT CODE

123 657 307 362 163 460 607 363 436 443 444 344 471 715 150 256 136 502 235 611 671 447 473 474 744 164 207 066 312 515 663 076 203 137

535 525 253 536 542 653 661 425 655 652 550 626 433 552 521 467 511 672 524 765 513 545 564 533 551 472 623 725 647 726 562 645

AUDIO/LOGIC BOARD

The Audio/Logic Board provides all audio and digital processing of the receive and transmit audio for digital processing by the Logic Board. The board also contains audio filtering, conv entional analog tone processing, and the receiver squelch. The Audio/Logic Board controls the operation of the radio and digitally processes the receive and transmit audio. The board contains a microprocessor and associated memory circuits including an EPROM for controlling the processor and a programmable "personality" memory (an Electrically Erasable PROM - EEPROM) to store customer freq uencies, tones and options. The micro processor provides control data to the Audio Signal Processor (ASP), conventional tone generation and detection, frequency data for the synthesizer, and sends and receives data to another microprocessor on the Display Board for the LCD.

SYSTEM BOARD

The system board controls the main input power to the radio. IGNITION SENSE input lead provides the necessary signals to the MOSFET switching circuit. The board also interfaces all option connections from the internal boards in the radio with the optional items outside of the radio. All external options for the radio, interconnect to the System Board through the back of the radio using an optional cable.

FRONT CAP ASSEMBLY

The Front Cap Assembly contains the Audio Amplifier Board. The Au dio Ampl ifie r Boar d prov ides c ompres sion of the microphone audio. It also provides audio com pression for the received audio in the discriminator and internal/external speaker audio paths. A 10-watt power amplifier is provided on the board to drive a 4-ohm internal/external speaker.

ACCESSORIES AND OPTIONS

PC PROGRAMMER OPTIONS

The radio is programmed using an IBM compatible personal computer equipped with a RS-232 port. Option TQ3370 provides the RS-232 serial interface unit an d the cable between the PC and the unit. An auxiliary power supply for the unit is also included but is not needed to program the radio.

Option TQ3372 p rovides the radio prog ramming cable between the PC interface unit and the radio microphone jack. MDX PC programming software Option TQ3346 (GEMARC only) or TQ3373 (EDACS) is provided in both 3.5 and 5.25 inch diskettes.

PC PROGRAMMED OPTIONS Carrier Control Timer (CCT)

The Carrier Control Timer turns off the transmitter af ter the microphone push-to-talk (PTT) switch has been keyed for a pre-programmed time period. A pulsing alert tone warns the operator to unkey and then rekey the PTT to continue the transmission. The timer can be programmed, using the PC programmer. Any time periods between 30 seconds and 7.5 minutes can be programmed in 30 second increment s. The timer can be enable d or disabled for each channel.

Channel Guard

Channel Guard provides a means of restricting calls to specific radios through the use of a Continuous Tone Coded

Squelch System (CTCSS), or a Continuous Digital Coded Squelch System (CDCSS). Tone frequencies range from

67.0 Hz to 210.7 Hz in 0. 1 Hz steps. Ther e are 83 standard PC programmable digital codes. The Channel Guard tone frequencies and codes are software programmable. Both tone frequencies and digital codes may be used. These codes and frequencies are listed in T able 1 - Channel Guard Tone

Frequencies and Table 2 - Digital Channel Guard Codes.

NOTE

To reverse the polarity of the digital Channel Guard codes in the PC programmer, type I ("inverted") before the code number, i.e. I023.

Squelch Tail Elimination (STE)

STE is used with tone and digital Channel Guard to eliminate squelch tails. The STE burst is transmitted when the microphone PTT is released. The receiving radio decodes the burst and mutes the receiver audio for 250ms. This mute time allows the transmission to end and to mute the squelch tail. The radio looks for STE on the received signal when the microphone is either on or off-hook. The STE is enabled for transmit and / or r eceive by P C p rogramming the r a d i o’s personality .

Retry Option

If no channel is free, the radio can be programmed to activate the Call Retry state and display ’RETRYING’ in the display. Retrying causes the radio to re vert to Idle m ode and scan for an incoming call while trying to acquire a free repeater approximately every 5 seconds for a 2 minute period.

Page 5

LBI-38848D

HARDWARE AND

HARDWARE OPTIONS

The location and pla cement of system har dware op tions are shown on Sheet 4 of the 800 MH z Dual Format MDX Mobile Interconnect Diagrams.

OPTION CABLE

Option Cable Option PMCD7Z (19C851585P14) is used to bring all option connections from the System Board through the back of the radio to the outside. This cable is required with all external options.

NOISE SUPPRESSION KIT OPTION

Noise Suppression Kit Option PMPD1A (consisting of Filter 19A148539G1 and Installation Manual LBI-31363) is available for installations where excessi ve alternator or electrical noises, present on the power cable, do not permit the radio to operate properly. Refer to the interconnect diagram for the radio and options.

POWER CABLE OPTION

18-foot Power Cable Option PMCD9A, (19B801358P17), is available for installations requiring more than the standard 9-foot cable.

EXTERNAL SPEAKER OPTION

External S peaker and Cable Option PMZM1T provides the user with a five-inch waterproof speaker in a LEXAN housing. PMCC9M is an 18 inch in terconnecting cable for the speaker. The radio’s 10-watt amplifier drives the speaker’s 4-ohm impedance. The speaker leads are connected to pins 2 and 9 of Option Cable Option PMCD7Z (19C851585P14), using External Speaker Cable Option PMCC9M (19A149590P8) (18 inches) included in the PMZM5T kit. A 16-foot cable, Option PMCD1W (19A149590P10 ) is also available.

EXTERNAL ALARM

External Alarm Horn Relay Option PMSU1C (19A705499P1) can sound the vehicle horn when a ca ll is received. The option connects to pin 13 of Option Cable Option PMCD7Z (19C851585P14) and is controlled by a front panel option switch.

SYSTEM DESCRIPTION

EDACS

The Dual Format MDX mobile 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 sc heme , la rge user gro ups can be a cc ess ed s imul taneously 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 su it each users needs via th e PC progra mmer for the radio.

The typical system configuration consists of at least 2 repeater stations (with a maximum number of 25) and the associated mobiles. One rep eater alw ays is a co ntrol channe l dedicated to sending out continuous control data and also to receive channel request data from the mobiles. When a mobile is first turned on, it scans the available list of fr equencies programmed in the personality EEPROM for a control channel. When a control channel is found, the mobile locks on to the frequency and monitors the data for a channel assignment (incoming call).

When receiving a channel assignment (incoming call), the monitoring mobile 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 mobile 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 mobile returns to the control channel frequency.

T o 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 mobile and transmits back a voice channel assignment on an unused channel.

When all available voice channels are in use, the control channel places the mobile into a queue, transmits a queue message back to the mobile, and will give a channel assignment to the requesting mobile 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 mobile and an alert signal is given to the user.

After the initiating mobile 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 mobile 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 mobiles are sent back to the control channel.

In normal operation, the transmitting mobile sends a high speed data burst to indicate that the user has unkeyed, causing all listening mobiles to switch back to the control channel.

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 mobile-to-mobile communications.

GE-MARC

The a repeater for each chan nel and th e users’ mobile radio uni ts. The system uses tone signalling with each mobile being assigned two and/or four tone group tone sequences. Groups of mobiles are assigned the same tones so that any unit can talk to all other units in the same group. A b lock diagram of the

GE-MARC MDX

When originating a call, the mobile identifies an idle repeater channel and interrogates it with a single burst of

"busy"

of interrogating mobile detects the acquisition tone, it then transmits its collect and group tones which the repeater regenerates for all idle mobile units in the system.

stop on the active channel if any of the programmed collect tones are detected and wait for group tone(s).

alert the operator of an incoming call and open their audio circuits. If the correct sequence is not detected, the idle mobiles will resume scanning the channels. Once the mobile is

"locked"

times out or the operator terminates the call.

tone; the repeater keys its transmitter and sends a burst

"acquisition"

The idle mobiles, which continually scan all channels, will

If the correct tone sequence is detected, the mobiles will

on a channel, it will remain there until the repeater

trunked mobile radio system consists of

is shown in Figure 1.

tone back to the mobile unit. When the

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 2.

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 u ser pla ce s a call. The ra dio r emain s 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 3.

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 mobile 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 mobile then looks for busy tone for a 90 millisecond period. If four tones are properly decoded, the mobile will then look fo r busy tone for 270 milliseconds.

When no valid tones are found, the mobile will resume scanning for a call with the next channel. When a busy tone is found, the mobile will enter the Ready mode. If busy tone is not detected, the mobile remains in the Idle mode and continues scanning channels looking for an incoming call.

Removing the ha nd set fr om th e ha ng er, pressing the PT T switch or pressing the SEND key on the handset 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 " 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 mobile will sound the low-fr equency tone and then return to the Idle mode and display

"BUSY".

If a channel with no busy tone is found, the mobile 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 mobile proceeds to transmit the group tones (either two or four tones). If a four-tone sequence is sent, the mobile 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

RETRYING

" in the display.

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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 p ush-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 causin g the unit to revert to Idle mode.

NOTE

If a call is initiated and a sequence of five beeps is sounded, the user cannot access the radio system because the m obile is out of receive range or is inoperative. Any subsequent call will be ignored for 20 seconds.

Figure 2 - GE-MARC Operational Modes

Figure 3 - Signal Timing Figure 1 - GE-MARC Block Diagram

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 fr om Idle mode (only) as the user presses the PTT switch on the microp hone, or comes "off-hook". 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 mobile 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 mobiles 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 mobile 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 mobiles 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 mobile and/or repeater.

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In a two-tone call, the mobile sends the collected tone for a programmable duration. In the four-tone call, the mobile always sends a 90-millisecond collect tone which the repeater regenerates and sends for the correct duration.

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 mobile and 180 milliseconds from the repeater.

RADIO OPERATION

A complete set of operating instructions for the Dual Format MDX ar e provided in LB I-38846 and ar e 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 communication s area and grou p. In this mode, audio channe l selection is also transparent to the user and is controlled via tone signalling.

In Conventional mode, the user s elects a channel and communicates on that channe l. In this mode , a syste m 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. Mo st features describe d in these op erating instructions can be enabled or disabled through programming. Both of these important factors must be considered when addressing the following instructions.

USER INTERFACE

Operating controls are located on the radio front panel and microphone.

The front panel LCD provides radio status and communication control information to the operator. The keypad is used for m an ua l n um be r en try f or i n dividu al cal ls ac ces s t o a telephone interconnect system and activation of various EDACS, GE-MARC, and conventional features.

Turning The Radio ON/OFF

The radio is turned ON/OFF by pressing the PWR

button in the upper left corner of the front panel. A self diagnostic test is performed when the radio is first turned on if enabled through programming. To turn the radio OFF, press the PWR button again.

ALERT TONES

The Dual Format MDX radio genera tes a set of unique

alert tones to indicate operating status. The following section identifies and describes the alert tones used in the Dual

Format MDX radio for Conventional, GE-MARC, and EDACS applications.

EDACS APPLICATIONS

CALL ORIGINATE ALERT

CALL QUEUED If one short, high-pitched tone sounds

AUTOKEY When the PTT is keyed to place a call on

SYSTEM BUSY If y ou press the PTT key and hear three

CALL DENIED A single, low-pitched beep sounds when

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.

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 a v ail able (see AUTOKEY).

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 generat es 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.

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.

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-OFRANGE/ 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

CALL ORIGINATE ALERT

INVALID CALL ORIGINATE ALERT

SYSTEM TONES

OUT-OFRANGE ALERT

If programmed, a single alert tone sounds when a group c all is received and a twotone alert (one high followed by one low tone) sounds for an individual call.

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 i s ready for normal conversation.

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.

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.

If NO SVC is d i s pl ayed and five beeps are sounded after attempting to place a trunked call, the radio is out of range of the GEMARC 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

SYSTEM TONES

(GE-MARC and Conventional operation.) A pulsed-tone signal is sounded for a preprogrammed time after PTT is pre ssed. 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.

The GE MARC radio may genera te other system tones to alert the user of custom programmed events. Contact the GEMARC system operator for details about these alert tones.

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