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Section 150-232-100
Revision 01
Page 3
2. APPLICATIONS
2.01 The primary application of the HLU-232 is to provide a “hot standby” backup unit when used in conjunction with
another HLU-232. Both units require the use of an HSA-232 Shelf Adapter for all applications. The HSA-232 Shelf
Adapter slides into a standard 220-type mechanics shelf, which provides access to the shelf card-edge connector.
2.02 The remote side of the circuit requires two HRU-412 remote units housed in an HRE-422 enclosure.
2.03 The general guidelines require that each loop have less than 35 dB of loss at 196 kHz, with 135 ohms driving
and terminating impedances. Table 1 provides a guide for the loss of various cable gauges at 196 kHz and 135
ohms. The table applies to the HDSL cable pairs between the HLU, HRU and HDU modules. Without specific
insertion loss measurement data, add 3 dB for each bridged tap and 1 dB for each cable gauge change.
TABLE 1. HDSL LOSS OVER CABLES
Cable Gauge
Loss at 196 kHz
(db/kft)
Ohms per kft
26/0.4mm
3.88
83
24/0.51mm
2.84
52
22/0.61mm
2.18
32
19/0.91mm
1.54
16
2.04 The HiGain system operates with any number of other T1, POTS, Digital Data Service (DDS) or other HiGain
systems sharing the same cable binder group. HiGain systems can be used with customers requiring DS1 service
on a temporary or permanent basis. The HiGain system also provides a means of quickly deploying service in
advance of fiber-optic transmission systems. With the HiGain system, service can be provided within hours. Fiber
optic systems can be installed at a leisurely pace and cut-over from the installed HiGain system when convenient to
do so. The installed HiGain system can then be easily removed and utilized elsewhere.
2.05 In addition to all of the standard HDSL line unit features found in the HLU-231, the HLU-232 provides
protection switching capability for applications where automatic switching from the primary circuit to a protection
circuit is required in the event of a primary circuit failure. Switches located on the HSA-232 Shelf Adapter and the
HRE-422 enclosure allow the user to enable (protection operation) or disable (non-protection operation) the
automatic switchover feature.