27
CHAPTER 5: Operation
Figure 5-9. Data mode with 511/511E.
5.3.4 U
SING THE
V.52 (BER) T
EST
-P
ATTERN
G
ENERATOR
To use the V.52 BER tests in conjunction with the remote digital loopback tests (or
with local line loopback tests), follow these instructions:
1. Locate the 511/511E toggle switch on the front panel of the Line Driver and
move it UP. This activates the V.52 BER test mode and transmits a 511 test
pattern into the loop. If any errors are present, the local modem’s red ER
LED will blink sporadically.
2. If the above test indicates no errors are present, move the V.52 toggle switch
DOWN, activating the 511E test with errors present. If the test is working
properly, the local modem’s red ER LED will glow. A successful 511E test will
confirm that the link is in place, and that the Line Driver’s built-in 511
generator and detector are working properly.
NOTE
The above V.52 BER tests can be used independently of the remote
digital loopback tests. This requires two operators: one to initiate and
monitor the tests at the local Line Driver and one to do the same at the
remote Line Driver. In this case, the test pattern sent by each Line Driver
will not be looped back, but will be transmitted down the line to the
other Line Driver. While one operator tests, the other monitors for
errors.
Framer
Processor
Processor
Framer
Pattern
Gen./Det.
Pattern
Gen./Det.
Loop
Control
Loop
Control
Line
X
X
X
X
