10
Issue 2, July 2004
61182118L1-5B
5. TESTING
Testing of the SHDSL circuit from the LTU includes
the following capabilities:
• Self Diagnostics
• Loopbacks
• Bit Error Rate Testing (BERT)
BERT
The 2W/4W SHDSL LTU contains a built-in Bit Error
Rate Test (BERT). The BERT involves injecting and
detecting a Pseudorandom Binary Sequence (PRBS)
toward the network on the selected payload (that is,
G.703 or entire SHDSL payload). The PRBS used in the
SHDSL NTU is PRS15 as defined in ITU-T 0.150 and
0.151. It is also known as a 2e-15 pattern.
The BERT is only accessible via the VT100 terminal
screens. Select “4. Test” from the Main Menu Screen.
From the Test Screen, the SHDSL BERT, G.703 BERT,
and options will appear, as described in
Table 6
.
Table 6. BERT Test Messages
Message
Description
BERT Status:
N/A
This BERT is currently unavailable. Only one BERT can be active at a time. For
example, if SHDSL BERT is active, all others will be N/A.
ACTIVE
This BERT is currently in progress. The source column identifies the originator of the
BERT in progress.
INACTIVE
This BERT is not currently in progress. After selecting a BERT type from the Test
Screen, the BERT Screen will appear, illustrating both BERT statistics and commands.
BERT Commands (with inactive BERT):
Start
Starts the BERT on the selected port/service.
Stop
Stops the BERT in progress.
BERT Commands (with active BERT):
Inject a Single Bit
Error
Injects one bit error into the pattern.
Restart
Clears out all statistics and restarts the BERT.
Statistical Messages:
Bit Error Rate
Total number of bit errors divided by the total number of bits in the current test interval.
Bit Error Count
Total number of bit errors in the current test interval.
Pattern Sync Loss
Count
Total number of times that the BERT has lost pattern sync.
Errored Seconds
Total number of seconds in which at least one bit error has occurred.
Total Elapsed Time
Total time that has elapsed since the test began (Days: Hours: Minutes: Seconds).
BERT status field information:
On
The BERT has started and has pattern sync.
Searching for pattern
The BERT has lost pattern sync.
Off
This BERT is currently off.
