Rec. ITU-T Q.551 (01/1994) … TRANSMISSION CHARACTERISTICS OF DIGITAL EXCHANGES
FOREWORD
CONTENTS
1 Introduction
1.1 General
1.2 Definitions
2 Characteristics of interfaces
2.1 Two-wire analogue interfaces
2.2 Four-wire analogue interfaces
2.3 Digital interfaces
3 Voice-frequency parameters of a connection between two interfaces of the same exchange
3.1 General
3.2 Transmission loss through the exchange
3.3 Group delay
3.4 Noise and total distortion
3.5 Crosstalk
3.6 Discrimination against out-of-band signals applied to the input interface
3.7 Spurious out-of-band signals received at the output interface
3.8 Echo and stability
4 Exchange transfer function - jitter and wander
Annex A … Information on the formulae used in this Recommendation to calculate weighted noise and signal-to-total distortion.
A.1 General
A.2 Weighted noise
A.3 Total distortion including quantizing distortion