150-712-200-02
Appendix A - Technical Reference
HRE-712 List 1 and List 2
July 26, 2000
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The physical locations of the HRE-712 doubler enclosures are determined by three deployment rules:
1
The first and most important deployment rule is to place the enclosures at the electrical limits of 35 dB of
each span. This places:
•
First doubler at the 35 dB location
•
Second doubler at the 70 dB location
•
Third doubler at the 105 dB location
•
Fourth doubler at the 140 dB location
This allows the maximum range of 175 dB to be realized, if the fifth span to the remote unit is also 35 dB.
2
If the first rule is not applicable and 35 dB spans cannot be implemented, the second rule is to make all the
spans the same electrical length (same 196 kHz loss). This minimizes the maximum span loss and ensures the
maximum operating margin, resulting in optimum transmission performances. Use Rule 3 if specific
application constraints prevent using Rule 2, or if two different circuit layout choices have the same
maximum span loss.
3
The third rule minimizes the power consumption and dissipation of the HLU which provides the doubler
power. Rule 3 requires Span 1 to be a minimum and Span 3 to be a maximum. This choice minimizes the I
2
R
loss in the cable pairs and reduces the thermal stress on the HLU.
Refer to HiGain technical advisory number TA-015, titled HiGain Operating Ranges, for more detailed
information regarding doubler deployment rules.
Only the HDU-409 and HDU-407 doublers can be used in circuits with more than three spans
(three or four doublers).
