Patent ID: 6925175

Claim:
Apparatus for an echo control device for use in canceling echo occurring in a communication channel and over a communication path that connects near- and far-end locations, the apparatus comprising: a far-end echo canceller having a delay register, the delay register imparting a given amount of delay to an input signal applied to the far-end echo canceller and destined for transmission over the path to the far-end location; and a measurement circuit for measuring length of the path and adjusting, in response to the measured length, the given amount of delay provided by the delay register, wherein the measurement circuit comprises: at least one detector for detecting first and second signals provided over the path so as to provide first and second detection outputs, respectively, wherein the first signal is provided by a first network switching system associated with the near-end location and the second signal is provided by a second network switching system associated with the far-end location and in response to reception of the first signal; and a long-haul processor, responsive to occurrence of first and second detection outputs, for measuring the path length and for providing a current delay value associated with the measured length, wherein the current delay value is used to set the given amount of delay provided by the register.