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The physical location of the doublers is driven by the following three deployment rules:
1Place the enclosures at the electrical limits, 35 dB, of each span. This places the first doubler at the 35 dB location, the second at 70 dB, and so on, allowing the maximum circuit range to be realized.
Caution must be observed when pushing doubler spans to their 35 dB maximum range. Refer to ADC’s Technical Advisory
2If Rule 1 is not applicable, then try to make all spans the same electrical length (same 260 kHz loss). This minimizes the maximum span loss and assures maximum operating margin, resulting in optimal transmission performance on the HDSL cable pairs. If specific application constraints preclude using Rule 2, or if two different circuit layout choices have the same maximum span loss, then use Rule 3.
3If Rules 1 and 2 are not applicable, make the spans closer to the ELU as short as possible while making the spans farther from the ELU as long as possible. This choice minimizes the I2R loss in the cable pairs, and reduces the thermal stress on the ELU. Following this rule minimizes the power consumption and dissipation of the ELU that provides the doubler power.
Only those ERUs that have a local powering option can be used in local
4 | January 26, 2000 |