Synthesis of digital the high-pass filters with quasi-monotonic step response based on the Bessel and Gaussian low-pass filters
Abstract
Synthesis of digital the high-pass filters with quasi-monotonic step response based on the Bessel and Gaussian low-pass filters
Incoming article date: 19.12.2018Digital signal processing is commonly used in system engineering of a new state of the art. The monotonic (maximally-flat) step response of the high pass filter is required, for example, in the case of testing for a negative signal present against the background of the positive rectangular impulse of rather higher amplitude. Or, conversely, to determine whether a positive signal is present against the background of the negative rectangular impulse. As this takes place, a signal pass is allowed, but a false detection is not allowed. The reason of the false detection can be a negative overshoot on the step response of the high-pass filter that is used for suppressing a dc component and decreasing flicker noises. This case we can see in electromyography, for example, when weak nerves signal follows the strong test electrical pulse. Approximations of analog filters via a bilinear transformation had been used to research of digital filters Bessel and Gaussian filters differing in the greatest step response monotone (especially Gaussian filters) and the results of these researches are outlined in this paper. The block diagrams of digital filters featuring a more monotonous step response, but with an overshoot on the frequency response in a passband near to the cutoff frequency are offered. The requirements have been analyzed at which a negative effect of this overshoot is being reduced.
Keywords: filter, digital, high pass, HPF, monotonic, maximally-flat, step response