Harris Constellation, Installation And Maintenance Manual

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Harris Corporation Constellation™
SERVICE CHANNEL
A
P P E N D I X
D
S
ERVICE
C
HANNEL
Loop System
The Constellation Service Channel is capable of operating as a repeater or a
terminal in a linear system or providing protection in a single or multiple loop
system.
The Service Channel can be set up in the following ways.
•
Linear or loop system
•
Master or slave (for loop system only)
•
External pilot on or off (for slave loop system only)
•
Local off-hook, enable or disable
The Service Channel in a loop system must always have one break in the loop
to prevent the data from propagating in a continuous loop. This break is always
done at the Master site in the A direction. Whenever a system failure occurs
that causes another break in the loop, the Master site must know about this
failure so it can remove its break. The pilot signal communicates this
information to the Master site. As long as there is only one break in the loop, all
system sites will have communication. All Service Channel loop systems, even
in multitude loops, work on this principle.