2.1.1.2.1
Exciter
The exciter on the XCVR RF board provides the transmitter functions for the base radio. The exciter
circuitry generates a low-level, modulated RF signal that passes to the power amplifier. It supports
various modulation types as well as bandwidths up to 25 kHz, through software programming.
The exciter also provides a controlled output power level to the power amplifier.
2.1.1.2.2
Receiver
The receiver provides either single receiver input or dual (HPD or TDMA) receiver inputs for dual
diversity. The receiver also provides enhanced diagnostic capabilities using an on board noise source
generator. It includes a wide tuning range (electronic varactor-tuned) preselector. The preselector is
electronically tuned to the desired receive frequency anywhere between 792–825 MHz, UHF R1 380–
435 MHz, UHF R2 435–524 MHz, or VHF 136–174 MHz.
2.1.1.3
Transceiver External Interfaces
The transceiver external interfaces include seven external ports, a switch, and LEDs. If a transceiver
option card is part of the transceiver, there are four additional external ports. See
Radio Front Connections on page 110
for information on the LEDs.
2.1.1.3.1
Transceiver Switch
The multifunction RESET switch on the front of the transceiver module is accessible through the drop-
down door to the left of the fans. The RESET switch has two functions:
Figure 7: Transceiver RESET Switch (viewable through the drop-down door)
Table 29: Transceiver Front RESET Switch Functions
User Action
Result
Press switch for less than 1 second
Toggles between Tx Inhibit and Tx Enable (LED
3 blinks amber)
Press switch for more than 3 seconds, then re-
lease
Transceiver Control Module Reset
MN003286A01-E
Chapter 2: GTR 8000 Base Radio Theory of Operation
63