Bit Error Rate Tester (Bert); Searching For Pattern; Table 11. Key To Symbols Used In Table 10 - ADTRAN Express 6500 Series Installation And Maintenance Practice

Directions
Customer (to NTU)
Network (to LTU)

Bit Error Rate Tester (BERT)

The SHDSL 2-Wire/4-Wire LTU provides an internal bit error rate tester (BERT) for the
injection and observation of a pseudo-random bit sequence (PRBS) to and from the SHDSL
interface on a per service basis.
The BERT runs only one test at a time. When the SHDSL 2-Wire/4-Wire LTU is injecting
PRBS, all ones are transmitted to the applicable G.703 port. The LTU BERT provides the
following ITU-T O.150 and O.151 compliant PRBS patterns:
• ALT
• 2047
• 2E15-1
• QRSS
The observation of data on a service under test commences automatically when a BERT test is
started. The following statistics become available on the VT100 screens and by EOC response
message when polled by NMS:
• Bit Error Rate (of format from 0.00x10E-0 to 9.99x10E-9)
• Bit Error Count (the number of bit errors during the test period)
• Pattern Sync Loss Count (the number of times a PRBS pattern sync has been lost during
the test period)
• Errored Seconds (a second that contains one or more PRBS bit errors)
• Outage Seconds (a count of ten or more consecutive Error Seconds - No outage indicates
one second occurs with no errors)
• Total Elapsed Time (of format DD:HH:MM:SS)
• BERT Status
– On
– Off

Searching for Pattern

The SHDSL 2-Wire/4-Wire LTU is able to reset the BERT counters when requested to do so by
an NMS or VT100 test screen. Injection of a single bit error from the NMS, VT100 test screen,
or front panel BERT pushbutton is also possible.
61230011L1-5B
Table 11. KEY to Symbols used in
No Loop
Customer Transparent
Customer Non-Transparent
AIS
Table 10
Loopbacks
LTU
AIS
Troubleshooting
Dual Sided
Network Transparent
Network Non-Transparent
19