Recent Advances in Variable Digital Filters

Abstract

Variable digital filters are widely used in a number of applications of signal processing because of their capability of self-tuning frequency characteristics such as the cutoff frequency and the bandwidth. This chapter introduces recent advances on variable digital filters, focusing on the problems of design and realization, and application to adaptive filtering. In the topic on design and realization, we address two major approaches: one is the frequency transformation and the other is the multi-dimensional polynomial approximation of filter coefficients. In the topic on adaptive filtering, we introduce the details of adaptive bandpass/band-stop filtering that include the well-known adaptive notch filtering.

Transfer Function Coefficients Calculation of the High Pass Frequency-Dependent Second-Order Components Using Special Phase Frequency Response Values

“…where 𝑥𝑥 = 0.0792𝑅𝑅𝑅𝑅 + 0.4521 from the ratio (11). As we can see from the graph represented in Fig.…”

“…The input signals processing is performed using frequency-dependent components (FDC), which are a combination of hardware and software [10][11][12][13][14]. In this case, the FDC characteristics depend on the transfer function coefficients, the calculation should take into account the amplitude-frequency response (AFR) and phase-frequency response (PFR).…”

Integrated improvement of the efficiency of computer control system of spatial orientation settings of drilling facilities

“…To improve the system quality, it is proposed to consider low-order tunable bandpass FDCs. Their use in the information and control system can reduce the computational cost and time for calculating new values when tuning the characteristics, as well as by cascading the same-type FDCs to increase the order of the processing path and simplify control [13,14].…”

Increasing the Efficiency of the Information Management System for Controlling the Spatial Orientation of Objects in Geophysical Research

“…To receive a modulated signal at the stationary part, it is necessary to have a bandpass-type FDC with the possibility of tuning the main frequency, the receiving band and the steepness of the AFC. It is difficult to manage such high-order components, because many of the transfer function coefficients of the components are interconnected [10][11][12][13][14]. Therefore, in most cases, for the control of characteristics, various compounds of the low-order FDC are used [15,16], due, for example, to the serial connection of the same type of low-order FDC.…”