Echo Canceller Employing Dual-H Architecture Having Split Adaptive Gain Settings

Abstract

An echo canceller circuit is set forth. The echo canceller circuit includes a digital filter having adaptive tap coefficients to simulate an echo response occurring during a call. The adaptive tap coefficients are updated during the call using a Means Squares process. A tap energy detector is also employed. The tap energy detector identifies and divides groups of taps having high energy from groups of taps having low energy. The high energy tap groups are smaller in number than the low energy tap groups. The high energy tap groups are adapted separately from the low energy tap groups using the Least Squares process. Still further, the high energy tap groups may be adapted using an adaptive gain constant a while the low energy tap groups are adapted using an adaptive gain constant a′, wherein a>a′.

1 . A method for processing adaptive tap coefficients for echo cancellation, the method comprising:
 dividing the adaptive tap coefficients into a high energy tap group and a low energy tap group;   adapting the high energy tap group separately from the low energy tap group using adaptive gain coefficients.   
   
   
       2 . The method of  claim 1  further comprising dividing the adaptive tap coefficients into a plurality of windows and designating a window having higher energy as the high energy tap group. 
   
   
       3 . The method of  claim 1  further including adapting the high energy group and the low energy tap group using Normalized Least Squares. 
   
   
       4 . The method of  claim 1  further including adapting the high energy tap group using a first adaptive gain coefficient and adapting the low energy tap group using a second adaptive gain coefficient. 
   
   
       5 . The method of  claim 4  wherein the first adaptive gain coefficient is greater than the second adaptive gain coefficient. 
   
   
       6 . The method of  claim 4  further including controlling speed of convergence and steady state error for adapting the high energy tap group and the low energy tap group as a function of adjusting the first adaptive gain coefficient and the second adaptive gain coefficient. 
   
   
       7 . The method of  claim 1  including adapting the high energy tap group separately from the low energy tap group based on an existence of a non-linear echo path response. 
   
   
       8 . The method of  claim 1  including adapting the high energy tap group separately from the low energy tap group based on an existence of a data call. 
   
   
       9 . The method of  claim 1  including adapting the high energy tap group separately from the low energy tap group based on an existence of a narrow bandwidth signal. 
   
   
       10 . An apparatus for processing adaptive tap coefficients for echo cancellation, the apparatus comprising:
 a divider module to divide the adaptive tap coefficients into a high energy tap group and a low energy tap group;   an adaptation module to adapt the high energy tap group separately from the low energy tap group using adaptive gain coefficients.   
   
   
       11 . The apparatus of  claim 10  wherein the divider module is arranged to divide the adaptive tap coefficients into a plurality of windows and designate a window having higher energy as the high energy tap group. 
   
   
       12 . The apparatus of  claim 10  wherein the adaptation module is arranged to adapt the high energy group and the low energy tap group using Normalized Least Squares. 
   
   
       13 . The apparatus of  claim 10  wherein the adaptation module is arranged to adapt the high energy tap group using a first adaptive gain coefficient and adapt the low energy tap group using a second adaptive gain coefficient. 
   
   
       14 . The apparatus of  claim 13  wherein the first adaptive gain coefficient is greater than the second adaptive gain coefficient. 
   
   
       15 . The apparatus of  claim 13  further including a control module to control speed of convergence and steady state error for adapting the high energy tap group and the low energy tap group as a function of adjusting the first adaptive gain coefficient and the second adaptive gain coefficient. 
   
   
       16 . The apparatus of  claim 10  wherein the adaptation module is arranged to adapt the high energy tap group separately from the low energy tap group based on an existence of a non-linear echo path response. 
   
   
       17 . The apparatus of  claim 10  wherein the adaptation module is arranged to adapt the high energy tap group separately from the low energy tap group based on an existence of a data call. 
   
   
       18 . The apparatus of  claim 10  wherein the adaptation module is arranged to adapt the high energy tap group separately from the low energy tap group based on an existence of a narrow bandwidth signal. 
   
   
       19 . A computer program product comprising a computer readable medium having computer readable code stored thereon, which, when executed by a processor, causes the processor to:
 divide adaptive tap coefficients into a high energy tap group and a low energy tap group; and   adapt the high energy tap group separately from the low energy tap group using adaptive gain coefficients.   
   
   
       20 . The computer program product of  claim 19  wherein the computer readable code, when executed by the processor, causes the processor to divide the adaptive tap coefficients into a plurality of windows and designate a window having higher energy as the high energy tap group.