363-206-285
Circuit Pack Descriptions
Issue 3 June 2001
7-93
removed and processed, and the 28 VT1.5s are stripped of their overhead to
produce 28 DS1s. The DS1s are then multiplexed back into the DS3.
Detailed Description of Operation 7
Transmission Circuitry 7
Transmit Direction. Figure 7-36 provides an overall block diagram of the BBG20
TMUX circuit pack. The transmit direction is the direction towards the STS-1
signal, and receive direction refers to the direction towards the DSX-3. In the
transmit direction, the BBG20 TMUX receives an incoming B3ZS encoded DS3
signal from the DSX-3. A closed protection relay contact routes the DS3 to a
circuit that splits the signal and sends one output to the companion (standby)
circuit pack and the other to its own receiver. The BBG20 TMUX receiver
performs equalization and clock recovery. The TMUX circuitry performs B3ZS
decoding and demultiplexes it into 28 DS1s. Performance monitoring is performed
on the DS1s before they are mapped into floating VT1.5s. The 28 VT1.5s are then
multiplexed into an STS-1 payload envelope using SONET asynchronous
mapping. The STS-1 path overhead and pointer bytes are added and the resulting
signal is sent to the high-speed OLIU circuit pack.
Receive Direction. The BBG20 TMUX receives STS-1 or VT1.5 data from both the
active and standby OLIUs, performs pointer interpretation, processes and
removes the path overhead, and strips the 28 VT1.5s of their overhead to produce
28 DS1s. The DS1s are then multiplexed back into the DS3.
A jumper allows the user to insert or remove an LBO network to provide the
required signal level and shape at the DSX-3.
To Next Page
Loading...
Need help?
General
