User Guide

NSD-5
3. System Module PAMS Technical Documentation
Page 48 Nokia Corporation Issue 1 05/02
the baseband for Tx out-of-lock detection.
2nd Rx VHF LO Synthesizer
This submodule contains a VHF VCO, a loop filter, and a single synthesizer. This synthe-
sizer is only tuned to a single frequency. The LO converts the received signal to baseband
data. This submodule will use a mask programmable synthesizer (Fujitsu).
System Reference Oscillator (VCTCXO)
This submodule is the reference clock for the engine. It is a voltage-controlled tempera-
ture compensated crystal oscillator that can be pulled over some range of its output fre-
quency. This allows for an AFC function to be implemented for any frequency accuracy
requirements. The oscillator is temperature compensated to maintain tight center fre-
quency control. Closed loop AFC operation will allow very close frequency tracking of the
base station to be done in PCS mode. This will enable the unit to track out aging effects
and give the required center frequency accuracy for CDMA in PCS bands.
Figure 24: The block diagram of synthesizer