Abstract: Signal capture control circuitry for use integrated in a switch for a telecommunications network, includes circuitry for selecting at least one of the call paths corresponding to a given call, for signal capture for analysis. Capture control circuitry for controlling the signal capture on the selected call path and for communicating with the call control circuitry is also provided. Having the signal capture control as part of the switch, and communicating with call control circuitry of the switch, makes it becomes possible to analyse previously inaccessible signals in the switch or in its inputs or outputs. Also, it becomes possible to trigger signal capture based on call control events which do not appear externally.

Abstract: In an echo canceller, an estimated echo signal is produced by an adaptive filter from a receive path signal and is subtracted from an incoming transmit path signal to produce an outgoing transmit path signal. Averages of signal levels on the receive path and the incoming and outgoing transmit paths are produced by exponential averaging. Adaptation of the adaptive filter is inhibited after initial convergence. Adaptation is enabled again in response to an echo attenuation parameter being less than a first threshold value and a variation of an echo attenuation parameter being less than a second threshold value, this situation representing a detected echo path change. The detection of an echo path change is inhibited in the presence of a near end signal.