363-206-305
Circuit Pack Descriptions
Issue 3 June 2000
7-25
Protection Circuitry
7
Optional revertive DS1PM circuit pack protection is provided with on-board relays
on the DSX-1 side and with logic selectors at the VT-G level on the OLIU circuit
packs. The SYSCTL controls these relays through two serial interfaces so that a
failure of one serial interface to the DS1PM does not prevent control of the relays.
If +5 V power on the DS1PM fails, the relays default to the protection state. If the
SYSCTL is removed, the relays remain in their current state.
Shorting contacts are provided in the backplane connectors so that when the
circuit pack is removed, the DSX-1 cable pairs short through to the protection bus.
When a DS1PM circuit pack is inserted, the relays are in the protection state until
the SYSCTL determines that the circuit pack is good.
The BBF3 DS1PM circuit pack can be mixed with the BBF1/1B. If mixed, the
protection circuit pack must be a BBF3 DS1PM circuit pack.
Fault Detection Circuitry
7
The DS1PM 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 intrashelf control bus. An out-of-service test is performed
whenever the DS1PM circuit pack is inserted or recovers from a transient failure.
The incoming DS1 signal is monitored for bipolar threshold crossings in excess of
10
-3
, 10
-6
, 10
-7
, or 10
-8
. Incoming VT1.5 signals are monitored for VT AIS, VT LOP,
and yellow.
Loopbacks
7
The DS1PM circuit pack provides a terminal loopback for testing. The terminal
loopback is provided on the DS1PM circuit pack for each DS1 low-speed interface.
The loopback is implemented inside the MUX/DEMUX/DESYNC device and
bridges the desynchronizer output signal (transmitted toward the DSX-1) back into
the DS1 synchronizer input. When the loopback is operated, the DS1 interface
device forces AIS toward the DSX.
Performance Monitoring
7
The DS1PM circuit pack provides PM circuitry for the following performance
parameters:
â–
VT path parameters derived from V5 coding violations
â–
DS1 PM derived from SF/ESF frame format depending on provisioning.
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