Transmissionparameters Page169 of 544
Option11C and 11C Mini TechnicalReference Guide

Impulse Noise

Impulse noise is defined as noise bursts or spikes that exceed normal peaks of
idle-channel noise. Impulse noise is measured by counting the number of
spikes exceeding a pre-set threshold; it is the number of counts above 55
dBm0 during a five minute interval, under fully loaded busy hour PBX traffic
conditions.
Variation of gain versus level
The variation of gain verses level (tracking error) measures how closely
changes in input levels causes corresponding changes in output levels.
The tracking error is measured in decibels and is defined as the deviation in
gain or loss through a range of input level relative to the gain or loss at the
reference frequency and level of 0 dBmO.
The two methods of measuring the tracking error are listed below.

Method 1

When a noise signal as defined in CCITT, recommendation 0.131 is applied
at the input of any interface, the gain versus level deviation at the output
meets the limits se t out in Table 47 .
Alternatively, when a sine wave input in the frequency range 700 - 1100 Hz
is applied at the input of any interface, the gain vs level deviation at the output
meets the limits given in Table48.
Table 4 6
Impulse Noise
Time Level Counts
5 Minutes >55 dBmO 0
Table 4 7
Variation of gain versus level method 1
Input Level dBm0 Gain Variation dB
-55 to -10 +/-0.5