363-206-285
Circuit Pack Descriptions
Issue 3 June 2001
7-21
Fault Detection Circuitry 7
The TG circuit pack has in-service and out-of-service built-in test capability. In-service
testing is continuous and errors are reported when they occur to the SYSCTL via the
intra-shelf control bus. An out-of-service test is performed whenever the TG circuit pack
is inserted or recovers from a transient failure.
The incoming DS1 references are monitored for:
â– LOS (128 consecutive zeros)
â– DS1 AIS
â– LOF
â– Excessive out-of-frame count
â– Greater than 10
-3
bit error ratio (BER).
Power Circuitry 7
The TG circuit pack receives two sources of −48 volts which are diode ORed, fused,
and filtered prior to conversion to a +5 volt source to power the rest of the circuit pack. A
failure of the fuse or converter causes the red FAULT LED to light.
TG Hardware Settings 7
The TG circuit pack option switches provide the following functions:
■DS1 Reference Line Coding — Selects either alternate mark inversion (AMI) or
AMI with bipolar 8-zero substitution (B8ZS) line coding for both DS1 input and
DS1 output.
■DS1 Reference Format — Selects either super frame (SF) or extended super
frame (ESF) for both DS1 input and DS1 output.
■Timing Mode — Sets timing mode to free run, external DS1, or line (formerly
loop) timed.
■DS1 output mode — Sets DS1 output (SF or ESF "all ones" signal) for intra-shelf
timing derived either from DS1 external input or from network timing distribution
derived from received line. Reference for DS1 timing output is taken from either
the main or function unit C OLIU groups.
â– Sets equalizer switch for proper cable length when provisioned for SYNC OUT
mode. Equalizer settings will be automatically set to shortest cable length when
the DS1 output is provisioned for MULT mode.
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