1
Scope
2 References
3 Terms and definitions
4 Abbreviations and acronyms
5 Characteristics of ALC devices
5.1 General
5.2 ALC characteristics
5.3 Tandemed operation
5.4 Delay performance
6 Test signals
6.1 Test signal for level and gain
checks
6.2 Electrical circuit noise
6.3 Environmental noise
7
Tests
7.1 Stability
7.1.1 Networks without pre-existing echo control
7.1.2 Networks with echo control
7.2 Echo
7.3 Noise tolerance
7.4 Signalling tones
7.4.1 DTMF tests
7.5 Voiceband data and facsimile
transmission
7.5.1 Disabler characteristics
7.5.2 Tests to confirm satisfactory voiceband data and fax performance when
an ALC device is not disabled by 2100 Hz
Annex A – Guidance for measuring signal levels in
networks
Appendix I – Guidance for the design of Automatic Level
Control (ALC) algorithms and their placement in the PSTN
I.1 Introduction
I.2 Discussion
I.3 ALC considerations
I.3.1 Location of ALC
I.3.2 Algorithmic and subjective
considerations
I.3.3 Equipment issues
I.3.4 Echo
I.3.5 Loop stability
Appendix II – Considerations relating to ALC deployment
II.1 Location of ALC
II.2 Tandemed operation