JPS57140040A - Echo canceller - Google Patents

Abstract

PURPOSE:To decrease the hardware, by providing a virtual adder, and virtually adding the content of a storage circuit of a transversal filter to a nonlinear code for tap coefficient correction, and renewing the storage circuit from the result. CONSTITUTION:A tap coefficient of a transversal filter synthesizing a virtual echo signal from a reception signal is stored in a storage circuit 3' in the form of nonlinear code. The nonlinear code in tap coefficient correction amount DELTAh from a corrective amount operator inputted from a terminal 1, and the content of the circuit 3' are compared at a comparison circuit 41, and according to the result of comparison, a larger signal between an output signal of the circuit 3' and the corrected amount DELTAh is selected at a selection control circuit 42, and the constituting bit is sent to an addition circuit 43. The circuit 43 adds or subtracts the predetermined value with a control signal from the circuit 42, the output signal is simulated as the sum between the tap coefficient and the amount of correction, the content of the tap coefficient stored in the circuit 3' is rewritten and multiplied by a reception input signal at a multiplication circuit 5 and outputted from a terminal 6 as a virtual echo signal.