User's Manual

68P81093C75-O December 1, 2000 3-1
Introduction
3
General
The Motorola PDR 3500 provides conventional analog, ASTRO™ ,
ASTRO CAI™ , and SECURENET™ capabilities in a compact,
software-controlled design. The station architecture and
microprocessor-controlled Station Control Module allow for fast
and reliable upgrading. FLASH memory in the Station Control
Module allows software updates to be performed locally (using
serial port), or remotely via modem.
Compact Mechanical
Design
The entire unit is housed in a lockable rugged, black aluminum
extruded case weighing approximately 4l lbs. Internal components
are mounted in a custom, removable chassis, designed to fit a 19"
rack.
State-of-the-Art
Electrical Design
Transmitter Circuitry
The station transmitter circuitry is designed for 50% duty cycle
operation at full rated power. Output power is continuously
monitored by an internal calibrated wattmeter. The wattmeter output
feeds a power control loop, continually adjusting and maintaining
the desired output power. All adjustments are electronic, including
deviation and output power.
Receiver Circuitry
The station receive circuitry features multiple bandwidth capability
(12.5, 25, or 30 kHz, depending on band), as well as ASTRO digital
operation. Injection signals for the 1st and 2nd local mixers are
generated by frequency synthesizer circuitry and are electronically
controlled by the Station Control Module. All receive signals
(analog, SECURENET , ASTRO , and ASTRO CAI ) are detected and
digitized before being sent to the Station Control Module; this
provides improved audio quality, consistent throughout the coverage
area.
Station Control Module The Station Control Module is microprocessor-based and features
extensive use of ASIC and digital signal processing technology. The
module serves as the main controller for the station, providing signal
processing and operational control for the station modules.