AUDIO BOARD
All of the data signals to and from the transceiver are
processed by the audio board. Functions provided by the audio
board circuitry include the receiver noise squelch, received
data filtering and amplification, transmit data filtering and
amplification, transmit deviation limiting, received high speed
(4800 baud) data filtering and limiting, and transmit data wave
shaping.
LOGIC BOARD
The logic board contains the microprocessor and associ-
ated support circuitry, EEPROM field programmable memory,
EPROM software, a custom high-speed data modem IC and
DAC. This board provides all the signalling functions (4800
baud high-speed and subaudible low-speed data generation
and detection) as well as alert tones, data loading for the
transceiver synthesizer, and control of transmit and receive.
The individual radio personality is field programmable using
the Electrically Erasable PROM (EEPROM).
ACCESSORIES AND OPTIONS
SQUELCH TAIL ELIMINATION (STE)
(Conventional Mode)
STE is used with 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 250 ms. 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
receive by PC programming the radio’s personality.
PC PROGRAMMING OPTIONS
The radio is programmed using an IBM compatible per-
sonal computer equipped with an RS-232 connector. Option
TQ-3310 provides the RS-232 serial interface unit and the
cable between the PC and the unit. Programming cable
19B801417P8 is used between TQ-3310 and the MTD Data
Only radio. An auxiliary power supply for the unit is also
included which is not needed to program the MTD.
NOISE SUPPRESSION KIT OPTION
Noise Suppression Kit Option PD1A (19A148539G1) is
available for installations where excessive alternator or elec-
trical noises present on the power cable do not permit the radio
to operate properly. Refer to the interconnect diagram.
REMOTE DATA TERMINAL OPTION
The Remote Data Terminal Option is required for data
operation over the RF to and from a mobile data terminal. The
Remote Data Interface (RDI) Option (19A149654P1) trans-
fers the data between the radio and the Remote Data Terminal.
POWER CABLE
A spare 9-foot power cable Option CC7F (19B801358P2)
is available for installations requiring more than the standard
9-foot cable.
SYSTEM DESCRIPTION
The MTD 900 MHz (digitally trunked) Data Only mobile
radio system provides fast access to available RF channels and
a degree of privacy due to selective signalling. This also
eliminates annoyance of other system user’s conversations
while ensuring that intended calls are not missed.
The system uses 4800 baud high-speed digital signalling
to identify individual units and user groups. The programming
used to determine transmit encoded groups and decoded re-
ceived groups is contained in the personality EEPROM con-
tained in the mobile. This information is individually
programmed to each user’s needs via the PC programmer for
the radio.
Typical system configuration consists of at least 2 repeater
stations (with a maximum number of 20), and the associated
mobiles. One repeater always is a control channel which is
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 frequencies
programmed in the personality EEPROM for a control chan-
nel. When a control channel is found the mobile locks onto the
frequency and monitors the data for a channel assignment
(incoming call).
LBI-38710
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