In this paper, a new class of gradient-based algorithm by using variable step-size technique for a second-order adaptive IIR notch filter is presented. An adaptation step-size parameter for the algorithm is worked out from the output signal and the gradient signal. The adaptive algorithm is used for detection of a sinusoid with additive white Gaussian noise, impulse noise and cancellation of 50-Hz interference in the recording of electrocardiogram signals. The performance of this algorithm is proved here to give high convergence speed, high impulse noise robustness and good efficiency of 50-Hz interference cancellation. Finally, the results of computer simulation are given to demonstrate the performance of the proposed algorithm for the adaptive IIR notch filter.
