Triple-Play Service Deployment

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Chapter 4: Troubleshooting the Copper Plant for IP Services
Reversed
The termination of a wire pair is reversed, for example, when a telephone
circuit tip at one end appears as ring at the opposite end.
Split
Between two pairs, one wire of one pair is reversed with one wire of
the second pair. Identify by use of third pair individual wire or by visual
inspection of the color coding at the termination.
Circuit balance
The conventional method of measuring circuit balance is to
measure the amount of power influence or noise to ground on a
pair. The technician then measures the amount of noise that
develops across the pair due to this power influence. Subtracting
noise from power influence gives the circuit balance. Power
influence is AC power line induced interference and is measured in
dBrnc—that is dB reference to noise through a C message filter.
The noise this causes on the pair is also measured in dBrnc.
The measurement result is in dB and the higher the number, the
smaller the amount of noise voltage across tip and ring and the
better the pair balance. A result of 60 dB or greater indicates the pair
has good balance and should be acceptable. For example, if a circuit
has a balance of 60 dB and has 72 dBrnc of power influence, it can
reject 60 dB of that which leaves only 12 dBrnc of noise on the pair.
This is a very small amount of noise and would not affect the
quality of the circuit.