User's Manual

800MHz & VHF Cell Enhancers
Maintenance Handbook
H/book Number:-50-078001HBKM
Issue No:-
A
Date:-02/09/2004
Page:-
68 of 88
5.18 1 & 3 Stage Alarm/Simplex/Mute PCB (12-002804 & 12-002213)
5.18.1 Description
In systems using simplex channel switching, it is necessary to be able to distinguish
between a ‘normal’ switching operation and erroneous modes where faults in the detector
circuitry may cause data errors but not necessarily fire the alarms. The simplex
alarm/mute board is designed to differentiate between normal and spurious switching
signals for single or multiple stage amplifiers.
5.19 Simplex Controller PCB (12-002811)
5.19.1 Description
The Simplex controller logic PCB monitors the receiver squelch output for a signal change
and activates the supply switching for either the uplink or down link path accordingly. In
normal operation, the low level Rx path is activated, and the associated Tx path is switched
off. When a signal is detected by the Rx Squelch module, the Rx squelch output goes low
(0v), which triggers the controller logic PCB. The PCB mutes the power supply to the
opposite path Rx LNA’s and switches on the power to the output power stage. In order to
prevent the power stage noise blocking the opposite path’s low level receiver, the power
amplifier is normally muted.