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 a path.
The apparatus measures a round-trip path delay interval of, e.g., a predefined
signaling tone(s) sent between international switching centers while establishing
an outbound call connection over the path. Once the delay is measured, the apparatus
sets echo delay of a corresponding long-haul echo canceller to accommodate that
delay. For a multi-channel facility (e.g., T1 or E1), path delay is separately
measured for each channel on that facility, and 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.
