Apparatus and an accompanying method for use in a long-haul echo control device for detecting changes in path length and compensating the performance of an echo canceller therein

摘要

Apparatus and accompanying methods for use in a long-haul echo control device to automatically measure sufficient changes in path length and compensate a long-haul echo canceller for resulting variations in echo occurring over those paths. Specifically, the inventive apparatus measures a round-trip path delay interval of, e.g., a predefined signalling tone(s) sent between international switching centers during the course of establishing an outbound call connection over that path. Once this delay interval is measured, the apparatus commensurately sets echo delay of a corresponding long-haul echo canceller to accommodate this path delay. For a multi-channel facility (e.g., T1 or E1), path delay is separately measured for each channel on that facility. Should the measured path delay sufficiently change for any one such channel, then the apparatus changes the echo delay to the same amount for the corresponding echo canceller associated with each and every channel on that facility.