Quantization Distortion; Intermodulation Distortion - Nortel Meridian 1 Succession 1000 Manual

Page 162 of 236

Quantization distortion

Intermodulation distortion

553-3001-182 Standard 1.00
Transmission characteristics—A-Law
Table 47
Crosstalk—A-Law
Connection
Line to line
Line to trunk
Trunk to trunk
Quantization distortion, shown in Table 48, is the distortion introduced when
an analog signal is encoded to digital format, and then decoded to analog
format. The quantization noise is the difference between the original analog
speech signal and the analog signal (speech plus noise) resulting from the
decoding process.
Table 48
Quantization distortion—A-Law
Input level
(dBm0)
0 to –30
–31 to –40
–41 to –45
Note: Input signal is 820 Hz sine-wave; output is measured with
psophometric weighting.
With the input driven with a composite signal consisting of two sine-wave
signals (denoted as f1 and f2), each in the range of 450–2050 Hz (but not
harmonically related) and of equal level in the range of –21 to –4 dBm0, the
system does not produce any 2f2-f1 intermodulation product at the output
October 2003
Crosstalk attenuation
(dB)
> 75
> 75
> 75
Minimum signal/distortion ratio
(dB)
33
27
22