# US 2013/0156210 A1 · Training an echo canceller in severe noise > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156210 A1 - Document ID: US20130156210A1 - Status: Published application - Kind: A1 - Application number: 13/719,742 - Filed: 2012-12-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Assignees: LSI Corporation - Inventors: David G. Shaw - Web page: https://patentgrep.com/patent/US20130156210A1 ## CPC - G10K 11/16: Methods or devices for protecting against, or for damping, noise or other acoustic waves in general (G10K11/36 takes precedence) - H04M 9/082: {using echo cancellers (echo cancellers per se H04B3/23)} - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08) ## Abstract An apparatus includes a non-adaptive filter, an adaptive filter, and a controller. The non-adaptive filter may have non-adaptive filter coefficients and be configured to develop a non-adaptive error signal as a function of the non-adaptive filter coefficients. The adaptive filter may have adaptive filter coefficients and be configured to develop an adaptive error signal as a function of the adaptive filter coefficients. The controller may be configured to monitor a quality of the non-adaptive and adaptive error signals and perform one or more of a full coefficient update, a partial coefficient update and a fractional coefficient update of the non-adaptive filter coefficients based on a comparison of the quality of the adaptive error signal to a determined current best-attained performance measurement. ## Claims ### Claim 1 An apparatus comprising: a non-adaptive filter, said non-adaptive filter having non-adaptive filter coefficients and configured to develop a non-adaptive error signal as a function of said non-adaptive filter coefficients; an adaptive filter, said adaptive filter having adaptive filter coefficients and configured to develop an adaptive error signal as a function of said adaptive filter coefficients; and a controller configured to monitor a quality of said non-adaptive and adaptive error signals and to perform one or more of a full coefficient update, a partial coefficient update, and a fractional coefficient update of said non-adaptive filter coefficients based on a comparison of said quality of said adaptive error signal to a determined current best-attained performance measure. ### Claim 2 (depends on 1) The system according to claim 1, wherein said controller is further configured to update said non-adaptive filter coefficients only when said quality of said adaptive error signal exceeds said determined current best-attained performance measure. ### Claim 3 (depends on 1) The system according to claim 1, wherein said controller is further configured to update said determined current best-attained performance measure based on a comparison of said quality of said non-adaptive and said adaptive error signals only when said quality of said adaptive error signal exceeds said determined current best-attained performance measure. ### Claim 4 (depends on 1) The system according to claim 1, wherein said quality of said non-adaptive error signal is a ratio of said non-adaptive error signal to an outgoing signal and said quality of said adaptive error signal is either (i) a ratio of said adaptive error signal to said outgoing signal or (ii) a ratio of said adaptive error signal to said non-adaptive error signal. ### Claim 5 (depends on 1) The system according to claim 1, wherein said non-adaptive filter is a foreground filter and said adaptive filter is a background filter. ### Claim 6 (depends on 1) The system according to claim 1, wherein said quality is represented by a signal strength level. ### Claim 7 (depends on 1) The system according to claim 1, wherein said controller is further configured to replace said determined current best-attained performance measure with said adaptive error signal when said quality of said adaptive error signal exceeds said determined current best-attained performance measure. ### Claim 8 A method of updating filter coefficients in a dual path adaptive filter, said method, comprising: generating a first error signal as a function of an incoming signal, an outgoing signal and filter coefficients of a first filter; generating an second error signal as a function of said incoming signal, filter coefficients of a second filter, and either said outgoing signal or said first error signal; monitoring a quality of said first and said second error signals; and updating said first filter coefficients based on a comparison of said quality of said second error signal to a determined current best-attained performance measure, wherein said first filter coefficients are updated using said second filter coefficients and a fractional coefficient updating technique. ### Claim 9 (depends on 8) The method according to claim 8, wherein updating said first filter coefficients occurs only when said quality of said second error signal exceeds said determined current best-attained performance measure. ### Claim 10 (depends on 8) The method according to claim 8, further comprising updating said determined current best-attained performance measure based on a comparison of said quality of said first and said second error signals only when said quality of said second error signal exceeds said determined current best-attained performance measure. ### Claim 11 (depends on 8) The method according to claim 8, wherein said quality of said first error signal is a ratio of said first error signal to said outgoing signal and said quality of said second error signal is either a ratio of said second error signal to said outgoing signal or a ratio of said second error signal to said first error signal. ### Claim 12 (depends on 8) The method according to claim 8, further comprising updating said determined current best-attained performance measure employing a smoothed average associated with said first error signal and said second error signal. ### Claim 13 (depends on 8) The method according to claim 8, wherein a speed of an averaging process used when the filter coefficients of the second filter modify the filter coefficients of the first filter is proportional to a predefined averaging parameter. ### Claim 14 (depends on 8) The method according to claim 8, further comprising replacing said determined current best-attained performance measure with said second error signal when said quality of said second error signal exceeds said determined current best-attained performance measure. ### Claim 15 An echo canceller, comprising: a non-adaptive filter having non-adaptive filter coefficients and configured to develop a non-adaptive error signal as a function of an incoming signal, an outgoing signal and said non-adaptive filter coefficients; an adaptive filter having adaptive filter coefficients and configured to develop an adaptive error signal as a function of either (i) said incoming signal, said outgoing signal and said adaptive filter coefficients or (ii) said incoming signal, said non-adaptive error signal and said adaptive filter coefficients; and a system for updating of said non-adaptive and said adaptive filter coefficients, including a controller configured to (i) monitor a quality of said non-adaptive and said adaptive error signals and (ii) update said non-adaptive filter coefficients based on a comparison of said quality of said adaptive error signal to a determined current best-attained performance measure, wherein said non-adaptive filter coefficients are updated using said adaptive filter coefficients and a fractional coefficient updating technique. ### Claim 16 (depends on 15) The echo canceller according to claim 15, wherein said controller is further configured to update said determined current best-attained performance measure based on a comparison of said quality of said non-adaptive and said adaptive error signals only when said quality of said adaptive error signal exceeds said determined current best-attained performance measure. ### Claim 17 (depends on 15) The echo canceller according to claim 15, wherein said quality of said non-adaptive error signal is a ratio of said non-adaptive error signal to said outgoing signal, and said quality of said adaptive error signal is either a ratio of said adaptive error signal to said outgoing signal or a ratio of said adaptive error signal to said non-adaptive error signal. ### Claim 18 (depends on 15) The echo canceller according to claim 15, wherein said non-adaptive filter is a foreground filter and said adaptive filter is a background filter. ### Claim 19 (depends on 15) The echo canceller according to claim 15, wherein said quality is represented by a signal strength level. ### Claim 20 (depends on 15) The echo canceller according to claim 15, wherein said controller is further configured to replace said determined current best-attained performance measure with said adaptive error signal when said quality of said adaptive error signal exceeds said determined current best-attained performance measure.