Kernel adaptive filter

About: Kernel adaptive filter is a research topic. Over the lifetime, 8771 publications have been published within this topic receiving 142711 citations.

Method and apparatus for automatic volume control in an audio system

Abstract: An audio system ( 100 ) is provided with improved adaptive filter ( 206 ) to automatically adjust signal gain depending on the ambient noise level. The original music signal passes through a normalized adaptive filter ( 206 ), and is subtracted from the ambient room signal detected by a microphone ( 120 ), resulting in an error signal that is an estimate of the ambient noise. The error signal is used to update a set of adaptation coefficients so that the normalized adaptive filter more accurately simulates the room transfer function, resulting in an better estimate of the ambient noise. The audio system ( 100 ) is calibrated automatically upon initial use to determine adaptation coefficients and noise threshold level to prevent runaway gain. System parameters are adjusted using a controller ( 124 ) with a user-friendly interface ( 400 ).

Method of performing convergence in a, least mean square, adaptive filter, echo canceller

Abstract: A method is described of decreasing convergence time in an adaptive echo canceller (20). The method includes the step of locating a primary echo within a filter vector based upon relative tap values within the filter vector. The filter vector is then narrowed, based upon the located taps. An estimated error is determined based, in part, upon the narrowed filter vector. An updated filter vector is produced based, in part, upon the estimated error.

Circuits and methods for compensating switched mode amplifiers

Abstract: A system and method for compensating switched mode amplifier (110). The amplifier system includes an adaptive filter (114) coupled to the output of circuitry that recovers the analog signal from the output of the switching amplifier circuitry (113). The adaptive filter (114) derives an inverse transfer function of the forward path through the system. The derived inverse transfer function is used to generate a coefficient map (115) which a compensation filter (121A, 121B) responsively compensates for from variations in the output load of the amplifier system. In the disclosed method, the deriving the inverse transfer function may further include calibrating the adaptive filter continuously, at system startup or in response to user demand.

Generalization of the linear matched filter concept to nonlinear matched filters

Abstract: A nonlinear matched filter based image correlator is investigated. The linear matched filter is expressed as a bandpass function containing the amplitude and phase of the Fourier transform of the reference signal. The bandpass filter function is then applied to a kth law nonlinear device to produce the nonlinear matched filter function. Analytical expressions for the nonlinear matched filter are provided. The effects of the nonlinear transfer characteristics on the correlation signals at the output plane are investigated. The correlation signals are determined in terms of the nonlinear characteristics used to transform the filter. We show that the nonlinear filter results in a sum of infinite harmonic terms. Each harmonic term is envelope modulated due to the nonlinear characteristics of the device, and phase modulated by m times the phase modulation of the linear filter function. The correct phase information of the filter is recovered for the first-order harmonic of the series. The envelope of each harmonic term is proportional to the kth power of the Fourier transform magnitude of the reference signal. We show that various types of filter such as the continuous phase-only filters can be produced simply by varying the severity of the nonlinearity. Nonlinear filters provide higher correlation peak intensity and a better defined correlation spot.