PairGain 150-1143-03, Руководство пользователя, Страница: 10 / 48

Product Overview 150-451-103-02, Revision 02
2 September 18, 1998 HDU-451 List 3
A
PPLICATIONS
The primary application of the HDU-451 HiGain Doubler is to extend the
delivery of T1 High Capacity Digital Service (HCDS) to customers over
metallic cable pairs, up to 24,000 or 36,000 feet (24 AWG). A doubler
application is shown in
Figure 1 on page 3 . A maximum of two HDU-451
units can be used in tandem on the same circuit.
Table 1 on page 2 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 and the HDU-451 as well as between the HDU-451 and a second
HDU-451 or the HRU. Add 3 dB for each bridged tap and 1 dB for each cable
gauge change.
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.
In order to achieve optimum performance, the electrical length (196 kHz loss)
of all doubler spans should be as close as possible to being equal. This
arrangement usually results in the highest operating loop margins.
Use Table 1 when calculating the electrical length of each span. If it is not
possible to make all spans equal, then choose the span lengths to reduce the
total power consumption of the HLU that powers the doublers. This is done
by minimizing the length of Span 1 and maximizing the length of Span 3.
Table 1. HDSL Loss over Cables
Cable Gauge Loss @ 196 kHz(dB/kft) Ohms per kft
26/0.4mm 3.880 83.3
24/0.51mm 2.841 51.9
22/0.61mm 2.177 32.4
19/0.91mm 1.535 16.1