User`s guide

Configuration
4-57
6700-A2-GY31-70
July 1999
Table 4-11. VF Impairments
VF Impairment Name Description
Signal/Noise Ratio Expressed in decibels (dB), the ratio of the amplitude of
the signal plus the noise to the amplitude of the noise.
Phase Jitter
(20–300 Hz)
Expressed in degrees, the amount of phase difference
(out-of-phase) between the transmitted carrier signal and
the received carrier signal.
Non-Linear Distortion Expressed in dB, the portion of the channel output that is
nonlinear in relation to the input signal. Harmonic and
intermodulation distortion would cause this kind of
distortion.
Frequency Offset Expressed in Hertz (Hz), the difference between the
transmitted carrier frequency and the received carrier
frequency.
Gain Hits The number of positive or negative gain hits during the
previous 15 minutes. A gain hit is a three dB change
lasting more than four milliseconds.
Phase Hits The number of phase hits during the previous
15 minutes. A phase hit is a phase change to a 1004 Hz
test signal greater than 20 degrees.
Impulse Noise The number of impulse hits during the previous
15 minutes. An impulse hit is a voltage surge of within six
dB of the normal carrier level lasting more than four
milliseconds.
Dropouts The number of dropouts during the previous 15 minutes.
A dropout is a normal carrier level decrease greater than
12 dB lasting more than four milliseconds.
Retrains The number of retransmissions during the previous
15 minutes.
Near End Echo Expressed in dB, the ratio between the transmit signal
and the receiver near end echo of the signal.
Far End Echo Expressed in dB, the ratio between the transmit signal
and the echo from the far end of the signal.
Far End Delay Expressed in milliseconds (Ms), the roundtrip delay of
the far end echo.
Echo Frequency Offset Expressed in Hz, the frequency offset of the far end
echo.
Signal Quality A number used to indicate the quality of the signal
where:
0 Excellent
1 Good
2 Fair
3 Poor
4 No Signal