Implementation of harmonic IIR notch filter with the TMS320C55x

A sinusoidal signal and its harmonics are often regarded as interferences to a system in many applications. This paper presents a harmonic infinite impulse response (IIR) notch filter in cascade form, and its implementation with digital signal processor (DSP) TMS320C55x for filtering out the sinusoid and its harmonics is introduced. The experiment results are demonstrated. One advantage of an adaptive filter is that it can track the frequency of the interference. An adaptive harmonic IIR notch filter is especially useful when the interfering sinusoid and its harmonics drift slowly in frequency. In this study, the adaptive algorithm for the harmonic IIR notch filter is presented, the LMS algorithm is applied to the first second-order section of the harmonic IIR notch filter to make it adaptively meet the application requirement.