363-206-305
Circuit Pack Descriptions
7-18
Issue 3 June 2000
The BBF3 DS1PM circuit pack can be mixed with the BBF1B. If mixed, the
protection circuit pack must be a BBF3 DS1PM.
Fault Detection Circuitry
7
The DS1 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 DS1 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 DS1 circuit pack provides a terminal loopback for testing. The terminal
loopback is provided on the DS1 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 DS1 circuit pack monitors VT path parameters derived from the V5 coding
violations.
Power Circuitry
7
The OLIU circuit packs supply +5 V power to the DS1 circuit packs. These two
inputs are diode ORed and the output is fused and then filtered before it is used to
power the rest of the circuit pack. A failure of the fuse causes the red FAULT LED
to light.
DS1 Hardware Settings
7
The line coding and line build out (LBO) are switch settable. (Other parameters
are provisioned through the software.) The locations of the DS1 circuit pack option
switches are shown in Figure 7-8 and Table 7-1and Table 7-2.
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