Motorola MTR2000 T5544 Instruction / Field Service Manual page 155

1
DESCRIPTION
The CLN1211 and CLN1212 Receiver Modules are described in this section. A general description, identification
of inputs and outputs, a functional block diagram, and functional theory of operation are provided. The informa-
tion provided is sufficient to give service personnel a functional understanding of the module, allowing mainte-
nance and troubleshooting to the module level. (Refer also to the Maintenance and Troubleshooting section of
this manual for detailed troubleshooting procedures for all modules in the station.)
General Description
Overview of Circuitry
Motorola Inc., 2005
All Rights Reserved
Printed in U.S.A.
RECEIVER MODULE
MODEL CLN1211 (with Varactor Preselector)
MODEL CLN1212 (without Varactor Preselector)
The Receiver Module provides the receiver functions for the VHF station.
The CLN1211 receiver module includes a varactor-tuned preselector; a
metal external preselector, which replaces the varactor-tuned preselector,
is also available. The receiver module performs highly selective bandpass
filtering and dual down conversion of the station receiver RF signal. A
custom receiver IC then performs an analog-to-digital conversion of the
received signal and outputs a differential data signal to the Station Control
Module.
The Receiver Module contains the following circuitry:
• Frequency Synthesizer Circuitry – consisting of a phase-locked loop
and VCO, generates the first LO injection signal
• Varactor-tuned Preselector Filter – provides bandpass filtering of the
station receiver RF input (not used if metal external preselector is
specified).
• Receiver Front End Circuitry – performs filtering, amplification, and
the first down conversion of the receiver RF signal
• Custom Receiver IC Circuitry – consists of a custom IC which per-
forms the second down conversion, filtering, amplification, and ana-
log-to-digital conversion of the receive signal
• A/D Converter Circuitry – converts analog receiver status signals to
digital format for transfer, upon request, to Station Control Module
• Local Power Supply Regulation – accepts +8V, +10V and +15V inputs
and outputs +5V, +10V, and +15V operating voltages.
Government & Enterprise Mobility Solutions
1301 E. Algonquin Road, Schaumburg, IL 60196
132 to 174 MHz
68P81096E19-B
09/30/05-UP