Harris Constellation, Installation & Maintenance

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Constellation™ November 2003
D-2 Service Channel
Loop System Configurations
Single Loop System Using Repeaters
Single Loop System Using Repeaters ( Figure D-1 ) shows the Service Channel’s
settings. Note that the Service Channel setting does not always correspond to
the radio or multiplexer system settings. However, in this case, it does.
To explain how this system works, a pilot A signal is generated from the Master
Repeater A site. The pilot signal propagates through three other Slave Repeater
Service Channels where it is received back at the Master Repeater B. The pilot
is looped and sent back to Master Repeater A where it is detected.
When the pilot is detected, the data is prevented from being transmitted or
received at Master Repeater A. This process causes a break in the loop which is
necessary under normal conditions.
However, if the pilot is not detected because of a system failure, a second break
in the loop is created. The data at Master Repeater A is now allowed to transmit
and receive by removing the original break.
When a sync alarm occurs in one direction, the Service Channel prevents data
from being transmitted or received in that direction.