1558A APS
4-14
LAPS Operation
4.9
BERT Testing
The user can perform BERT testing by accessing the Main-
tenance screen. In the lower right hand and left hand por-
tions of the display are the command/toggle/information
fields that are used for BERT testing. These fields and their
use are discussed below.
Pattern: Specifies which pattern will be transmitted during
test. When the 3 or 5-bit, user-defined pattern is chosen, the
user may type in any pattern of 1s and/ or 0s to be transmit-
ted. Pressing <return> with the cursor positioned on this
field will cause the pattern to be transmitted for the period
of time specified in ‘Test Time’. The choices are: QRSS,
1:8, 3:24, all Ones, all Zeros, user definable 3-bit, and
user definable 5-bit.
NOTE: If the 1558A DTE is configured for AMI opera-
tion, the test sets must be set to generate either a 511,
2047, or 1:7 pattern. If the 1558A is configured for B8ZS
operation, any pattern may be used (511, 2047, 1:7,
QRSS, 3:24, etc.). When sending a 1:7 pattern, though,
some T1 test sets inherently cause generation of a yellow
alarm condition.
Test Time: Defines the run-time of test pattern generation
and error accumulation and starts the test. Pressing <return>
with the cursor positioned on this field will cause the
selected pattern to be transmitted for the specified period of
time. If the Maintenance menu is exited, pattern testing is
halted. The choices are: 15 Minutes, 30 Minutes, 45 Min-
utes, 1 Hour, and Continuous.
Runtime: Shows the amount of time elapsed since a timed
Pattern test began. Note that this field only appears on the
screen when a test is running.
Near CRC Errors: A display-only field for viewing the
number of CRC errors which are received at the Near Target
receive path.
Far CRC Errors: A display-only field for viewing the
number of CRC errors which are received at the Far Target
receive.Far CRC Errors are only reported if the 1558A is
configured as a Master. Slave 1558A units do not report Far
CRC Errors.
Reset Errors: Pressing <return> with the cursor positioned
on this field causes both the Near and Far CRC accumula-
tors to be cleared (only if Master 1558A).
It is important to understand that the 1558A does not allow
testing (loop or BERT) on the active path. To perform test-
ing on a given path the user must first configure the path to
the Standby mode, Soft Inhibit mode or Manual Inhibit
mode. Once the path to be tested is in one of these modes,
the LAPS will allow the user to perform testing.
BERT testing can be performed either to loopbacks or
straight away to the far end. To perform a BERT test, the
user should follow the steps discussed below.
1)
Select the path to be tested using the TARGET toggle
field.
2)
Move the cursor highlight to the Pattern field and then,
using the spacebar, toggle the field until the desired user pat-
tern is display. The available patterns are; QRSS, 1:8, 3:24,
all Ones, all Zeros, user definable 3 -bit, and user definable
5-bit.
3)
Next, move the cursor highlight to the Test Time field
and then, using the spacebar, toggle the field to the desired
test time. The choices are 15 minutes, 30 minutes, 1 Hour,
24 Hours, and Continuous.
4)
After performing Steps 1 - 3, move the cursor highlight
to either the Test Time or Pattern field and then momentarily
depress the <enter/return> key. The system will immediately
begin to generate the selected pattern on the selected path
for the selected time interval. Observing the Near and Far
end CRC errors counters will assist the user in determining
if the error problem is occurring in the transmit or receive
path.
Note: The LAPS system cannot generate loops while a
BERT test is in process. Also, if the user exits the ‘Mainte-
nance’ screen while a BERT is running, the BERT stops.
While running the test, the user may reset the CRC error
counters by moving the cursor highlight to the Reset Errors
field and momentarily depress the <enter/return> key. This
will reset the Near and Far CRC error counters to zero. Per-
forming an error reset does not stop the BERT test in
progress.
The user may stop the BERT test at any time by simply
moving the cursor highlight to either the Pattern or Test
Time command fields and then depress the <enter/return >
key. The system responds by turning off the Runtime clock
display. To restart the test, simply depress the <enter/return>
key again. The system responds by applying the selected
BERT pattern and restarting the Runtime clock display.
