Rec. ITU-T G.712 (09/1992) – TRANSMISSION PERFORMANCE CHARACTERISTICS OF PULSE CODE MODULATION CHANNELS
FOREWORD
CONTENTS
0 Scope
1 General
    1.1 Measurement considerations
    1.2 Port definitions
2 Relative levels at voice-frequency ports
    2.1 Relative levels at 4-wire ports (E4)
    2.2 Relative levels at 2-wire ports (E2)
3 Adjustment of actual relative levels
    3.1 Adjustment of the decoding side (Tin to Eout)
    3.2 Adjustment of the encoding side (Ein to Tout)
    3.3 Load capacity (overload point)
4 Short- and long-term variation of loss with time
5 Nominal impedance and return loss of voice frequency ports
    5.1 Nominal impedance
    5.2 Return loss
6 Impedance unbalance about earth
    6.1 Longitudinal conversion loss
    6.2 Longitudinal conversion transfer loss
7 Attenuation/frequency distortion
8 Group delay
    8.1 Absolute group delay
    8.2 Group delay distortion with frequency
9 Idle channel noise
    9.1 Weighted noise
    9.2 Single frequency noise
10 Discrimination against out-of-band signals
    10.1 Input signals above 4600 Hz at analogue ports E4 and E2
    10.2 Input signals below 300 Hz at 2-wire analogue port E2
    10.3 Overall requirement (4-wire only)
11 Spurious signals at the channel output port
    11.1 Spurious out-of-band signals at the channel output port
    11.2 Spurious in-band signals at the channel output port
12 Total distortion, including quantizing distortion
13 Variation of gain with input level
14 Crosstalk
    14.1 General
    14.2 Interchannel crosstalk, analogue-to-analogue channels
    14.3 Crosstalk measurements of individual primary multiplexers
15 Interference from signalling
    15.1 4-wire analogue to 4-wire analogue channels
    15.2 2-wire analogue to 2-wire analogue channels
    15.3 4-wire analogue-to-digital channels
    15.4 2-wire analogue-to-digital channels
16 Echo and stability at 2-wire ports, E2
    16.1 Terminal balance return loss (TBRL)
    16.2 Stability loss (SL)
ANNEX A – Alternative measurements using band limited noise signals
ANNEX B – Method of derivation of the signal-to-total distortion ratio for the A-law
ANNEX C – Alphabetical list of abbreviations used in this Recommendation