363-206-305
Circuit Pack Descriptions
Issue 3 June 2000
7-45
T1EXT Quick Reference Summary
7
Transmit Functions
7
Major transmit functions of the T1EXT circuit pack are as follows:
a. Receives two AMI or B8ZS encoded DS1 signals from a T-line
b. Recovers DS1 and NRZ data from each DS1 signal
c. Synchronizes and maps each data signal to a VT1.5 synchronous payload
envelope (SPE)
d. Inserts VT path overhead
e. Multiplexes two VT1.5 SPEs to a byte-interleaved VT-G signal
f. Provides the VT-G signal to an OLIU circuit pack.
Receive Functions
7
Major receive functions of the T1EXT circuit pack are as follows:
a. Receives a SONET VT-G frame synchronizing signals from its associated
OLIU
b. Demultiplexes the VT-G into two VT1.5 signals
c. Terminates VT path and the embedded DS1 signal from each VT1.5 SPE
d. Desynchronizes the DS1 signals
e. Encodes each DS1 signal into either AMI or B8ZS format
f. Preequalizes (with line build out) each DS1 and provides them to a T-line
as bipolar signals.
Control Functions
7
The major control functions of the T1EXT circuit pack are as follows:
a. Protection switching for OLIU circuit pack protection
b. VT path overhead processing
c. Internal fault detection
d. Inventory information (
CLEI
code, date of manufacture, etc.)
e. Monitors a DS1 signal with SF or ESF frame format and generates PM
data.
f. Provides simplex 60mA line current.
Maintenance Signal Functions
7
The major maintenance signal functions are as follows:
a. Monitors DS1 signal for near-end and far-end performance
b. Detects VT path AIS
c. Inserts DS1 AIS toward fiber and toward T-line
d. Inserts and detects VT path yellow signal.
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