Service manual

1-2 Description: Introduction
1.1.2 Electrical Design
1.1.2.1 Transmitter Circuitry
The base station/repeater transmitter circuitry is designed for continuous duty operation and may be
operated at full rated power. Output power is continually monitored by an internal directional coupler.
The forward power voltage from the coupler feeds a power control loop which continually adjusts and
maintains the desired output power. All adjustments are electronic, including deviation and output
power.
1.1.2.2 Receiver Circuitry
The base station/repeater receiver circuitry features multiple bandwidth (12.5 kHz, 20 kHz, 25 kHz,
and 30 kHz) capability. Injection signals for the first and second mixers are generated by frequency
synthesizer circuitry electronically controlled by the Station Control Module (SCM). All receive
signals (analog) are detected and digitized before being sent to the SCM, providing improved,
consistent audio quality throughout the coverage area.
NOTE: For UHF band, 30 kHz bandwidth is not supported.
For digital mode, only 12.5 kHz bandwidth is supported.
1.1.2.3 Station Control Module
The SCM is microprocessor-based and features extensive use of ASIC and digital signal-processing
technology. The SCM serves as the main component for the base station/repeater, providing signal-
processing and operational control for the base station/repeater modules.
1.1.2.4 Wireline Circuitry
The station wireline circuitry options provide a wide variety of telephone interfaces and remote
control mechanisms such as Tone Remote Control and DC Remote Control. Telephone line
connections are easily made to the wireline circuitry via connectors on the rear of the station.