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Circuit Pack Descriptions
7-90 Issue 3 June 2001
Power Circuitry 7
The BBG19 DS3 circuit pack receives two sources of −48 volts that are in turn
diode ORed, fused, and filtered before conversion to +5 volts to power the rest of
the circuit pack. A failure of the fuse or converter causes the red FAULT LED to
light.
BBG19 DS3 Quick Reference Summary 7
Transmit Functions 7
The BBG19 DS3 transmit functions are as follows:
■ Receives a B3ZS-encoded DS3 signal from a data services device
■ Recovers DS3 clock and NRZ data
■ Optionally checks and/or corrects P-bit parity errors
■ Synchronizes the data signal to STS-1 signal rate
■ Inserts STS-1 path overhead
■ Provides the STS-1 signal to the OLIU circuit packs.
Receive Functions 7
The following receive functions are performed by the BBG19 DS3 circuit pack:
■ Desynchronizes the incoming STS-1 signal
■ Terminates the STS-1 path
■ Optionally checks and/or corrects P-bit parity errors
■ B3ZS encodes the outgoing DS3 signal
■ Pre-equalizes the DS3 signal (with LBO) and transmits it to a data services
device.
Control Functions 7
The major control functions are as follows:
■ STS-1 path overhead processing
■ Internal fault detection
■ Inventory information (
CLEI
code, date of manufacture, etc.).
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