System for the generation of a time variant signal for suppression of a

Abstract

System for the generation of a time variant signal (sec(t)) for suppression of a primary signal (d(t)), provided with a control unit (1) provided with an adaptive digital filter (10, 11) for providing a cancellation control signal (u(t)), cancellation-generating unit (2) for generating a cancellation signal which is propagated along a secondary path with a transfer function and then providing the time variant signal (sec(t)), sensor unit (4) for measuring a residual signal (.epsilon.(t)), update unit (5) provided with a first input for receiving the output signal (y(t)), a second input for receiving the cancellation control signal (u(t)), and a third input for receiving said reference signal (x(t)), wherein the update unit (5) is provided with a prediction filter (8) which is arranged to calculate a predicted value (y.sub.pred (t)) based on the signals actually received on the first, second, and third inputs such that said predicted value (y.sub.pred (t)) equals an anticipated, calculated output value of the sensor unit (4), calculated under the assumption that filter coefficients of the adaptive digital filter (10, 11) were already updated in accordance with the signals actually received on the first, second, and third inputs, said predicted value (y.sub.pred (t)) being used by the update unit to calculate the update signal (up(t)) to be transmitted to the control unit (1).