Chapter 2 MTR3000 Receiver Module
2.1 Description
The Receiver Module is described in this section. A general description, identification of inputs and
outputs, a functional block diagram, and functional theory of operation are provided. The information
provided is sufficient to give service personnel a functional understanding of the module, allowing
maintenance and troubleshooting to the module level.
2.1.1 General Description
The Receiver Module consists of a Receiver RF board in a clamshell housing assembly. It provides
the Receiver functionality for the MTR3000 Base Station/Repeater and performs highly-selective
bandpass filtering and dual down-conversion of the desired RF signal. A custom Receiver IC then
performs an analog-to-digital conversion of the desired received signal and outputs a differential data
signal to the Station Control Module (SCM).
2.1.1.1 Overview of Circuitry
The Receiver Module contains the following circuitry:
• Frequency Synthesizer Circuitry – Consists a phase-locked loop and Voltage-Controlled
Oscillator (VCO), generates the first LO injection signal
• Varactor-tuned Preselector Filter / Fixed Preselector Filter (800/900 MHz) – Provides
bandpass filtering of the station Receiver RF input
• Receiver Front End Circuitry – Performs filtering, amplification, and the first down conversion
of the Receiver RF signal
• Receiver-specific IC Circuitry – Consists a receiver-specific IC which performs the second
down conversion, filtering, amplification, and analog-to-digital conversion of the receive
signal
• Analog to Digital Converter (ADC) Converter Circuitry – Converts analog Receiver status
signals to digital format for transfer, upon request, to the SCM
• Local Power Supply Regulation – Accepts +8 V, +10 V and +14.2 V inputs and outputs
+2.775 V, +3.3 V, +5 V, +10 V, and +14.2 V operating voltages
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