Patent ID: 6259680
Filing Date: 2001-07-10
Classification: H04B

Abstract:
A method for echo cancellation in a communication system utilizing a bidirectional transmission medium, said method including the steps of:(a) transmitting a first signal in a first direction through said medium at a first signaling rate within a corresponding first bandwidth, said first signal characterized by an echo at said first signaling rate within said first bandwidth;(b) receiving a second signal in a second direction through said medium at a second signaling rate within a corresponding second bandwidth, such that said first and second bandwidths are partially overlapped, said step of receiving said second signal further comprising the steps of:(i) filtering said second signal such that all transmit energy above a Nyquist rate corresponding to said second signal is eliminated; and(ii) sampling said second signal at a sampling rate that is equal to or greater than said Nyquist rate for said second signal;(c) canceling said echo from said second signal, said canceling step comprising the steps of:(i) converting said first signal into a signal having a sampling rate less than a Nyquist sampling rate for said first signal, but equal to said sampling rate for said second signal;(ii) replicating an echo signal at a sampling rate equal to said sampling rate for said second signal; and(iii) subtracting said replicated echo signal from said second signal; whereby said echo canceling is performed within said second bandwidth.