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Loopbacks
L
S
OSS OF
The HAIS option provides two choices for the T-1 transmit outputs at both
the HLU and HRU for HDSL loss of sync conditions.
HAIS S
ET TO
The 1 Loop choice causes the AIS pattern to be transmitted at both T-1
outputs when either of the two HDSL loops experience an out-of-sync
(LOSW) condition or when a margin alarm occurs. This choice causes the 12
channels on the surviving loop to be lost as they are replaced by the AIS
pattern. However, it does allow both downstream and upstream equipment to
be made aware of the loss of one HDSL loop or a loop with a low margin.
This is the preferred setting to be able to initiate an AIS state with just one
conductor open in either of the HDSL pairs. Short loops, below
approximately 16 dB of loss at 200 kHz, can remain in sync with one
conductor open. Since the loop is still in sync, no LOSW condition occurs.
However, the margin on a one-conductor loop drops approximately 5 to 10
dB. If the Margin alarm is set to 5 dB below normal margin at 'turn-up,' then
when one conductor does open, a margin alarm occurs and causes the AIS
condition. This alerts maintenance personnel to the problem.
HAIS S
ET TO
The 2 Loops choice requires both HDSL loops to be out-of-sync (LOSW)
before the AIS signal is transmitted. This choice preserves the integrity of the
12 surviving channels when just one loop is lost.
U
SING THE
HiGain system testing allows you to verify the integrity of the HDSL
channels to the HLU as well as the DS1 channels to the customer and the
HLU DSX-1 interface. The HRU-419 displays system condition messages at
the Remote and Maintenance Terminals, and through color-coded LED
displays on the front panel. The Front Panel Messages are included in
2 on page
5.
46
W
YNC
ORD
1 L
OOP
2 L
OOPS
L
OOPBACK
September 25, 1998
(LOSW) C
(LB) B
UTTON
150-419-100-03>
ONDITIONS
HRU-419 List 1
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