Ericsson GE-MARC VE MDR Manuals

Maintenance Manual LBI-38696 Printed in U.S.A. Mobile Communications MDR MOBILE RADIO TABLE OF CONTENTS DUPLEXER INTERFACE BOARD . . . . . . . . . . . . . . . LBI-38700 RF BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . LBI-38697 SYSTEM BOARD . . . . . . . . . . . . . . . . . . . . . . . . . LBI-31924 LOGIC BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . LBI-38392 AUDIO BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . LBI-38391 FRONT CAP ASSEMBLY . . . . . . . . . . . . . . . . . . . . LBI-38699 HANDSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LBI-38698 SERVICE SECTION . . . . . . . . . . . . . . . . . . . . . . . LBI-38701 Copyright© March 1992, Ericsson GE Mobile Communications Inc. TABLE OF CONTENTS (Cont’d) Page STATUS INDICATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 No Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Roam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 In Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Bar Status Indicators (||||) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Mute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 AUDIBLE INDICATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 SELF CHECK TEST ALERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 CALL RECEIVED ALERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 CALL ORIGINATE ALERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 SYSTEM BUSY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 OUT OF RANGE ALERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 INVLAID CALLORIGINATE ALERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 CARRIER CONTROL TIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 GE-MARC SYSTEM TONES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 KEY DEFINTIONS/FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 MISCELLANEOUS KEYS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Push-To-Talk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Volume Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Volume Down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 FUNCTION KEYPAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Send . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Clear (CLR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 End . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Recall (RCL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Store (STO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Alphabet Keys (A, B, C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Function (FCN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 NUMERIC KEYPAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 0-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Asterisk (*) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Pound (#) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 TELEPHONE EXTENDED FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 TABLE OF CONTENTS Page SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 RF BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Synthesizer circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Transmitter Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Receiver Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 DUPLEXER INTERFACE/TALK-AROUND BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 AUDIO BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 LOGIC BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 SYSTEM BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 FRONT CAP ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 ACCESSORIES AND OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 PC PROGRAMMER OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 PC PROGRAMMED OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Carrier Control Timer (CTT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Channel Guard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Squelch Tail Elimination (STE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Hook Switch Programming Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Retry Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 HARDWARE AND HARDWARE OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 HANDSET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 HANDSET CABLING OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 OPTION CABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 NOISE SUPPRESSION KIT OPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 POWER CABLE OPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 EXTERNAL SPEAKER OPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 EXTERNAL ALARM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 SYSTEM DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 OPERATIONAL MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 IDLE MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 WAIT MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 READY MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 GLOSSARY OF SYSTEM TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 RADIO OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 VISUAL INDICATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 ALPAHNUMERIC STATUS INDICATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Busy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Retrying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Wait . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 LBI-38696 LBI-38696 1 TABLE OF CONTENTS (Cont’d) Page BASIC OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 VOLUME ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 AREA SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 GROUP SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 CHANNEL ACTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 PLACING A DISPATCH CALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 PLACING AN INTERCONNECT OR DISPATCH OVERDIAL CALL . . . . . . . . . . . . . . . . . . . . 9 ENDING A CALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 RECEIVING A CALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 DIRECT MODE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 CONVENTIONAL MODE OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Call Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Last Digit Clear And Display Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Storing Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Recalling Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Hotkeys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Last Number Redial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Unlocking The Mobile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Locking The MRD Mobile Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Backlilght . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 External Speaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Call Hold (Mute) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Simplex Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 DTMF Digit Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Delay After DTMF Star (*) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 CHANNEL GUARD TONE FREQUENCIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 DIGITAL CHANNEL GUARD CODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 ASSEMBLY DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 INTERCONNECTION DIAGRAMS: 800 MHz Duplex Mobiles (System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Standard 800 MHz Duplex Mobile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 800 MHz Duplex With Talk-Around . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 800 MHz Duplex Mobile (Options) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 APPLICATION DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 SPECIFICATIONS* GENERAL Operating Voltage 13.8 Volts ±20% Battery Drain Receiver (13.8 Vdc) Off .01 Amperes (maximum) Squelched .8 Amperes (maximum) Unsquelched 1.00 Amperes (maximum at 3 Watts audio) Transmitter (13.6 Vdc) 6.0 Amperes (maximum at 10 Watts RF) Channel Spacing 25 kHz Frequency Stability ±2.5 PPM (±.00025%) Temperature Range -30°C to +60°C (-22°F to +140°F) Dimensions (H x W x D) (Less Accessories) Height 54mm (2.15 inches)(body)/62.5mm (2.46 inches) (nose) Width 181.5mm (7.15 inches) Depth 246mm (9.7 inches) Weight 2.55 kg (5.6 pounds) Antenna Impedance 50 Ohms TRANSMITTER Frequency Range 806.0125-820.9875 MHz 851.0125-865.9875 MHz (with Talk-around option only) Output Power 10 Watts (100% duty cycle) Audio Sensitivity 150-250m Vrms Spurious and Harmonics -56 dBc (below the carrier) Audio Distortion 5% maximum @ 1000 Hz Modulation Limiting +5 kHz maximum FM Hum and Noise -45 dB Audio Frequency Response per EIA Standards Within +1, -3dB of a 6dB/Octave pre-amphasis curve from 300-3000 Hz. RECEIVER Frequency Range 851.0125-865.9875 MHz Acceptable Frequency Displacement ±4 kHz minimum Sensitivity (12 dB SINAD) -113 dBm minimum in duplex Spurious Response 70 dB minimum Adjacent Channel Selectivity 65 dB minimum ±25.0 kHz Intermodulation 60 dB minimum Audio Frequency Response Within +2, -8dB of a 6 dB/octave de-emphasis curve from 300-2700 Hz Audio Output 3 Watts Audio Distortion 5% maximum at 1000Hz *These specifications are intended primarily for use by service personnel. Refer to the appropriate Soecification Sheet for complet specifications. LBI-38696 LBI-38696 2 GENERAL DESCRIPTION The Ericsson GE-MARC VE MDR Mobile Radio is a synthe- sized, wideband radio that uses integrated circuits and microcom- puter technology to provide high performance trunked and con- ventional operation. The radio provides 10 Watts of RF power output in the 806.0125-820.9875 MHz and 851.0125-865.9875 MHz bands. The receiver operates in the 851.0125-865.9875 MHz band. All radio functions are stored in a programmable Electrically Erasable PROM (EEPROM). The radio is field programmable using an IBM compatible personal computer with the following equipment: • Serial Programming Interface Module TQ3310 • Programming Cable TQ3361 • MDR Programming Software TQ3355 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 MDR Mobile Radio assembly consists of the following circuit boards and assemblies: • Duplexer Interface Board A4 19D903504 or • Talk-Around Board A4 (optional) 19D903507 • RF Board A2 19D902123G18 • System Board A5 19D901891 • Logic Board A1 19D902172 • Audio Board A3 19D902188 • Handset Interface Board A9 19D903510 • Handset A8 344A3783P1 • Duplexer 19B801362P3 The circuit boards are all mounted on a main casting to provide easy access for servicing. Interconnect plugs are used to connect the boards to eliminate pinched wires and other wiring problems. RF BOARD The RF board includes the programmable frequency synthe- sizer, transmitter exciter, receiver front end and IF circuitry. Synthesizer Circuit The synthesizer generates all transmit and receive RF frequen- cies. The synthesizer frequency is controlled by the microproces- sor located on the Logic Board. Frequency stability is maintained by a temperature compensated reference oscillator module. Trans- mit audio is processed on the Audio and Logic Boards, and applied to the RF board to modulate the VCO and TCXO. Transmitter Circuit The transmitter consists of a fixed-tuned exciter module, a PA module and a power control circuit. The PA module provides up to a 20-Watt output to drive the duplexer. The power control circuit controls the PA module by processing a DC feedback signal from the duplexer interface board to maintain constant output power across the band. The RF output level is internally adjustable for rated power. Thermistors in the control circuit protect the PA from overheating by reducing the power output level. Receiver Circuit The dual conversion receiver circuit consists of a front end section, 45 MHz first IF, a 455 kHz second IF, and FM detector. All audio processing and squelch functions are accomplished on the Audio Board. DUPLEXER INTERFACE/ TALK-AROUND BOARD Two versions of this board exist. The standard duplexer inter- face board contains only a directional coupler and the Talk-around board contains a directional coupler and RF switching circuitry to provide talk around transmit capability. Radio Power distribu- tion is also present on this board. The directional coupler samples the duplexer output and provides a DC signal proportional to the detected power to the RF board power control circuitry. AUDIO BOARD The Audio Board provides analog to digital and digital to analog conversion of the receive and transmit audio for digital processing by the Logic Board. The board also contains analog audio filtering, conventional analog tone processing, and the receiver squelch. LOGIC BOARD The 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 which include an EPROM for controlling the processor and a programmable "personality" memory (an Electrically Eras- able PROM - EEPROM) to store customer frequencies, tones, and options. The microprocessor provides control data to the Digital Signal Processor (DSP), conventional tone generation and detection, frequency data for the synthesizer, and sends and receives data to/from the handset for the LCD display and the keypad commands. SYSTEM BOARD The system Board controls the main input power to the radio. The handset POWER switch and the IGNITION SENSE input lead provide the necessary signals to the MOSFET switching circuit. The board also interfaces all option connec- tions 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 Handset interface board. The Handset interface board provides compression of the microphone audio from the handset. It also provides audio compression for the received audio from the radio to handset speaker audio and external speaker audio paths. A 3-watt power amplifier is provided on the Handset interface board to drive a 4-ohm external speaker. Separate mute control for the external speaker and handset audio are also provided. ACCESSORIES AND OPTIONS PC PROGRAMMER OPTIONS The radio is programmed using an IBM compatible per- sonal computer equipped with a RS-232 port. Option TQ3310 provides the RS-232 serial interface unit and the cable between the PC and the unit. An auxiliary power supply for the unit is also included which is not needed to program the MDR. Option TQ3361 provides the radio programming cable between the PC interface unit and the radio microphone jack. MDR PC programming software Option TQ3355 provides both the 3.5 inch and 5.25-inch diskettes. PC PROGRAMMED OPTIONS Carrier Control Timer (CCT) The Carrier Control Timer turns off the transmitter after the microphone push-to-talk (PTT) switch has been keyed for a pre-programmed time period. A pulsing alert tone will warn the operator to unkey and then rekey the PTT to continue the transmission. The timer can be programmed, using the PC programmer, to time out for 30 seconds to 7.5 minutes in 30 second increments. The timer can be enabled or disabled for each channel. In Duplex mode a quick 2-note alert is heard at the interval of the carrier timer to let the user know that interval has elapsed. 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). Channel Guard may be used only in the conventional mode, not in the GE-MARC trunked mode. Tone frequencies range from 67.0 Hz to 210.7 Hz in 0.1 Hz steps. There are also 83 standard PC programmable digital codes. The Channel Guard tone frequencies and codes are software programmable. Tone frequenies and digital codes cannot be mixed on the same RF frequency/channel. However, multiple channels can be programmed with the same frequency and different CG tones or DCG codes. These tone frequencies and digital codes are listed in Table 1 - Channel Guard Tone Frequencies and Table 2 - Digital Channel Guard Codes (refer to the Table Of Contents). Squelch Tail Elimination (STE) STE is used with tone and digital Channel Guard to elimi- nate 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 handset is either on or off-hook. The STE is enabled for transmit and/or receive by PC programming the radio’s personality. Hook Switch Programming Option "Off Hook Call" originate and "On Hook Call" terminate can be enabled using the PC programmer. When this option is enabled placing the handset on the handset holder will termi- nate a call. When originating a call, the number to be called can be keyed in, or recalled from memory, and when the handset is removed from the holder the call will be initiated without LBI-38696 LBI-38696 3