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Chapter 2 — Transmission parameters
Idle Channel Noise
Impulse Noise
553-3121-100
Standard 2.0
Idle channel noise is noise in the absence of a signal. It is the short-term
average absolute noise power, measured with C-message weighting. The
3 k Hz flat measurement uses equal weighting for all frequencies in the
20-3000 Hz range. The values are shown in Table 9.
Table 9
Idle Channel Noise
Connection
Line — Line
Line — Trunk
Trunk — Trunk
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.
Table 10
Impulse Noise
Time
5 Minutes
September 1998
Message
Noise
dBrnC0
<20
<20
<20
Level
>55 dBmO
3 kHz
dBm0
<29
<29
<29
Counts
0
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