Rev. 11/10/00
17
Testing DSSC, DAML, OR UDC Pair Gain Line
DSSC
,
DAML
, and
UDC
pair gain lines carry approximately 70 to 130 VDC
between the Central Office Terminal (COT) and the Remote Terminal Unit
(RTU)
located at the subscriber end. These lines also exhibit Stressed Noise readings of
80 dBrnC and higher in the
Stress
test mode. The excessive voltage on these lines
will not harm the Sidekick but the readings become invalid. To ensure accurate
readings when testing pair gain lines, follow the simple rules listed below:
1.
Be familiar with local procedures when disabling a pair gain system that
serves more than one customer.
2.
If local procedures permit, disconnect the C.O. pair from the
RTU
. Or, if so
equipped, use the disconnect switch on the
RTU
to isolate the C.O. pair.
The line running between the
COT
and
RTU
will revert to a
POTS
line in
approximately 60 seconds. Perform Sidekick tests as usual.
NOTE
:
Because it is normal for the
COT
to transmit a 130
VDC
pulse every
one (1) to five (5) minutes, the meter will also pulse.
3.
Full path (subscriber to C.O.) testing can be accomplished by disconnecting
and jumping past the
RTU
.
NOTE
:
Testing pair gain lines from the subscriber side (instrument to
RTU
)
can be done without disabling or disconnecting the
RTU
.
Troubleshooting Tips
The closer you are to the source of the trouble, the higher the Stressed Noise
readings will be. Example: If a pair exhibits a reading of 40 dBrnC on the F2
distribution at the cross-connect and a reading of 50 dBrnC at the protector/
SNI
,
you can assume that the trouble is closer to the customer premise. If Stressed
Noise readings decrease (below 50) as you move toward the cross-connect or
beyond the customer’s serving terminal, you can assume that you were closer to
the trouble at the protector/
SNI
.
The Sidekick will read pulses sent across the pair from Maintenance Test Units
(
MTU
s') in the
Leakage
test mode. If this happens, simply set the
Reverse
switch
to the opposite position.
MTU
s' will also create an imbalance on the line when you
test from the customer side. To compensate, remove the
MTU
from the line while
performing the
Stress
test from the customer side.
Construction Wire ("C" Rural) will produce high Stressed Noise readings (50+
dBrnC). In this case, simply verify that the wire reads the same at both ends.
The following examples illustrate some typical faults. Readings of 30 dBrnC at the
cross-connect are taken with the jumper in place. Readings given for the C.O., F1,
and F2 are taken with the jumper disconnected. All readings are in dBrnC units.
