1
General
2
Characteristics of interfaces
2.1 Characteristics of interface C2
2.1.1 Exchange impedance
2.1.2 Impedance unbalance about earth
2.1.3 Relative levels
2.2 Characteristics of interface Z
2.2.1 Exchange impedance
2.2.2 Impedance unbalance about earth
2.2.3 Relative levels
3
Characteristics of half-connections
3.1 Characteristics common to all 2-wire analogue interfaces
3.1.1 Transmission loss
3.1.2 Group delay
3.1.3 Single frequency noise
3.1.4 Crosstalk
3.1.5
Total distortion including quantizing distortion
3.1.6 Discrimination against out-of-band
signals applied to the input interface
3.1.7 Spurious out-of-band signals received at
the output interface
3.1.8 Echo and stability
3.2 Characteristics of interface C2
3.2.1 Nominal value of transmission loss
3.2.2 Noise
3.2.3 Values of total distortion
3.3 Characteristics of interface Z
3.3.1 Nominal value of transmission loss
3.3.2 Noise
3.3.3 Values of total distortion
Appendix I –
Impedance strategy in 2-wire networks
I.1 Introduction
I.2 General equations for
unloaded cables
I.3 General impedance
considerations of a hybrid
I.3.1 Cable input impedance Z2 and the hybrid input impedance ZT
I.3.2
Balance impedance ZB
I.4 Echo considerations
I.4.1 Talker echo loudness rating TELR
I.4.2 Sidetone masking rating STMR and listener
sidetone rating LSTR
I.5 Applications
I.6 Analysis of loop
impedance variation by means of a special impedance diagram
I.7 Conclusions
I.8 Examples of impedances
Z2
and compromise nominal impedances ZTand ZB
I.8.1 Cable input impedance Z2 and hybrid input impedance ZT
I.8.2 Balance impedance ZB
I.8.3 Application of the special impedance
diagram
I.8.4 Echo considerations