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6.4.2 Loops and Patterns
The following section describes the Remote Loopback/BER test
modes.
When Remote Loop/511 or Remote Loop/511/E
Remote Digital
is enabled via the front panel switch, the
Remote unit's Restart Timer is set to one
minute. This is because when the 511/511E
generator is initiated on the local unit, the
Remote framer begins seeing unframed pack-
ets. The Remote unit can not distinguish the
511/511E pattern from the line being disconnect-
ed, so the Restart Timer has been lengthened to
allow the pattern generator to function. Once the
511/511E test is started, the Local unit changes
its' Restart Timer to one minute. The pattern
originates within the Processor and is sent to
the Remote unit. It is then looped back to the
Local unit where it is evaluated for errors. After
45 seconds, the Pattern Generator will timeout
and stops sending the pattern. The ER led will
begin blinking until the user turns off the
511/511E switch.
Loop
Framer
Pattern
Line
Contr
ol
Gen/Det
Processor
Figure 11: Block Diagram Two Model 1089s Communicating over the DSL Span
6.4.3 Using the V.52 (BER) Test Pattern Generator
To use the V.52 BER tests in conjunction with the Remote Digital
Loopback tests, follow these instructions:
1.
Locate the Remote Loop/511 & Remote Loop/511E toggle
switch on the front panel of the 1089 and move it DOWN.
This activates the Remote Loop with V.52 BER
and transmits a "511" test pattern into the loop. If any errors
are present, the local unit's red "ER" LED will blink
sporadically.
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Loop
Pattern
Framer
Gen/Det
Contro
l
Processor
2.
If the above test indicates no errors are present, move the
test switch V.52 toggle switch UP, activating the "511/E" test
with intentional errors present. If the test is working properly,
the local unit's red "ER" LED will blink. A successful "511/E"
test will confirm that the link is in place, and that the Model
1089's built-in "511" generator and detector are working
properly.
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