Reduction of Signal Overshooting Caused by Cutoff Frequency Changing in the Controlled Digital Butterworth Low Pass Filter

Abstract

Digital filters have been widely utilized in modern telecommunications systems, signal processing, and electronic systems applications Signals suffer from different disruption and noises in real life, using filter can eliminate these noises and ensure a clear signal. Sometimes a digital filter might experience a transient event which represented by an overshoot of the signal. This transient may, for example, be the result of changing the cutoff frequency during filter operation by changing its coefficients. In this paper we proposed a compensation technique to remove this overshoot using nth order digital Butterworth LPF filter. The proposed method demonstrates that we can eliminate an overshoot by using multiple filtering processes to the input signal to obtain a clear real signal with minimum to no disruption. By using the MATLAB program, the transient process resulting from the restructuring of the filter was investigated and the formulas were checked compensation of this transient process. It was found that the application of such compensation reduced the negative effects of the transition process. This decrease depends on the order of the filter, the adjustment coefficient (the ratio of cut frequencies before and after adjustment) and the moment of adjustment (for the periodic signal).