Circuit Pack Descriptions
7-42 Issue 8.0 July 2002
Quick Reference Summary 7
Transmit Functions 7
The DS3 circuit pack performs the following transmit functions:
a. Receives three B3ZS-coded DS3 signals (44.736 Mb/s) from a DSX-3
panel (or equivalent)
b. Recovers DS3 clock from each DS3 signal
c. Synchronizes and maps each DS3 signal to an STS-1 (51.84 Mb/s)
synchronous payload envelope (SPE)
d. Inserts STS-1 path overhead and pointer bytes
e. Multiplexes three STS-1 signals to a 155.52 Mb/s signal
f. Provides the 155.52 Mb/s signal to an OC48 TRMTR circuit pack.
Receive Functions 7
The DS3 circuit pack performs the following receive functions:
a. Receives a 155.52 Mb/s signal from an OC48 RCVR circuit pack
b. Demultiplexes the 155.52 Mb/s into three STS-1 signals
c. Extracts the path overhead and the embedded DS3 signal from each
STS-1 signal
d. Desynchronizes the DS3 signals
e. Encodes each DS3 signal into a B3ZS format
f. Provides three DS3 signals to a DSX-3 panel (or equivalent).
Timing and Control Functions 7
The DS3 circuit pack performs the following timing and control functions:
a. Selects the primary or secondary 155.52 MHz timing signal from the TG3
(DS1) circuit packs
b. Provides relays for low speed protection switching
c. Provides selector circuitry for high speed protection switching
d. Performs internal fault detection and interfaces with the LNCTL circuit pack
using the board controller local area network (BCLAN)
e. Provides one loopback for each DS3 signal
f. Stores inventory information (CLEI code, serial number, etc.)
g. Controls the circuit pack faceplate FAULT LED.
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