CONTENTS

 0     Scope
 1     General
        1.1     Measurement considerations
        1.2     Port definitions
        1.3     Abbreviations
 2     Relative levels at analogue 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 (T_in to E_out)
        3.2     Adjustment of the encoding side (E_in to T_out)
        3.3     Load capacity (overload point)
 4     Short- and long-term variation of loss with time
 5     Nominal impedance and return loss of analogue 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 interference
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 analogue ports E4 and 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
                 11.1.1     In-band input signal
                 11.1.2     Overall requirement
       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, channels between analogue ports
                 14.2.1     Far-end crosstalk
                 14.2.2     Go-to-return crosstalk for channels between 4-wire analogue ports
       14.3     Interchannel crosstalk, channels between analogue and digital ports
                 14.3.1     Far-end and near-end crosstalk measured with analogue test signal
                 14.3.2     Go-to-return crosstalk measured with analogue test signal
                 14.3.3     Far-end and near-end crosstalk measured with digital test signal
                 14.3.4     Go-to-return crosstalk measured with digital test signal
15     Interference from signalling
       15.1     Channels between 4-wire analogue ports
       15.2     Channels between 2-wire analogue ports
       15.3     Channels between 4-wire analogue and digital ports
       15.4     Channels between 2-wire analogue and digital ports
16     Echo and stability at 2‑wire ports, E2
       16.1     Terminal Balance Return Loss (TBRL)
       16.2     Stability Loss (SL)
Appendix I – Alternative measurement methods using band limited noise signals
        I.1        Variation of gain with input level
        I.2        Total distortion, including quantizing distortion
Appendix II – Method of derivation of the signal-to-total distortion ratio for the A-law