PairGain 150-1140-42, Manual

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Revision 01 December 22, 1997 150-319-142-01
24 PairGain Engineering - Plant Series HLU-319 List 4B
The HAIS (HDSL AIS) option provides two selections (1LP and 2LP) for the
T1 transmit outputs at both the HLU-319 List 4B and HRU for HDSL
loss-of-sync conditions. Selecting 1LP causes the AIS pattern to be
transmitted at both T1 outputs when either of the two HDSL loops experience
a loss of sync word (LOSW) condition or when a margin alarm occurs. This
causes the loss of the 12 channels on the surviving loop because they are
replaced by the AIS pattern. However, it allows both down and upstream
equipment to be made aware of the loss of one HDSL loop or of a loop with
low margin. The 1LP selection is the preferred setting to initiate an AIS state
with just one conductor open in either of the HDSL pairs. Short loops, below
about 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 from 5 to 10 dB. Thus, if the margin
alarm is set to 5 dB below the normal margin at turn-up, when one conductor
opens, a minor alarm occurs and causes the AIS condition. This alerts the
maintenance personnel of the problem.
2LP requires both HDSL loops to be out of sync before the AIS signal is
transmitted. This choice preserves the integrity of the 12 surviving channels
when just one loop is lost.
Table 3. HLU-319 List 4B System Setting Menu Options
Option Parameter Description
Q 0* Sets the equalizer to DSX-1 for 0 m to 40 m.
133 Sets the equalizer to DSX-1 for 41 m to 80 m.
266 Sets the equalizer to DSX-1 for 81 m to 121 m.
399 Sets the equalizer to DSX-1 for 122 m to 162 m.
533 Sets the equalizer to DSX-1 for 163 m to 200 m.
* Indicates HLU-319 List 4B factory (default) settings. (Continued)