Search

Search Results

• METHOD AND ALGORITHM FOR SYNTHESIS OF CONTROLLED CHEBYSHEV DIGITAL FILTERS OF THE FIRST KIND OF LOW FREQUENCIES BASED ON THE BILINEAR TRANSFORMATION METHOD

  I.I. Turulin, S.M. Hussein

  2022-11-01

  Abstract ▼

  The article presents a technique for the synthesis of controlled digital recursive Chebyshev lowpass
  filters of the first kind with an infinite impulse response. The frequency response of such filters has
  ripples in the passband and is as flat as possible in the stopband. Controllability is understood as an
  explicit dependence of the filter coefficients on the cutoff frequency. The technique is based on the bilinear
  transformation of the transfer function of the analog low-pass filter prototype and the frequency
  transformation of the amplitude-frequency characteristics of the obtained digital filter. The main idea ofthe technique is that for an analog prototype filter with a cutoff frequency of 1 rad/s, the parameters of
  the transfer function of biquadratic or bilinear links, which have the dimension of frequency, will be
  numerically equal to the correction factors for similar parameters of a controlled filter with an arbitrary
  cutoff frequency. As an example, the synthesis of a digital Chebyshev filter of the first kind of the fifth
  order is considered. In this article, the transfer function of an arbitrary order filter is represented as a
  cascade connection of II order links if the filter is of an even order. In the case of an odd order greater
  than one, one cascaded link of the first order is added. Despite the relative simplicity of the frequency
  conversion, in its practical use for digital filters synthesized using computer-aided design of digital filters
  (or using reference books containing calculated prototype low-pass filters for various approximations
  of the frequency response of an ideal low-pass filter), a series arises non-trivial specific moments
  that complicate the engineering use of this method of synthesizing controlled digital filters. Therefore, in
  addition to the technique, a step-by-step algorithm has been developed that allows one to synthesize a
  filter without knowing these moments. The algorithm is implemented in the Mathcad environment; as
  an example, a digital recursive Chebyshev filter of the 1st kind of the 5th order is calculated.
  The example shows the calculated coefficients of a digital controlled low-pass filter, which explicitly
  depend on the cutoff frequency, the amplitude-frequency characteristics of this filter and its lowfrequency
  prototype converted into a filter with the same cutoff frequency, the amplitude-frequency
  characteristics are given in the same coordinates. Due to the good formalization of the algorithm, the
  latter is suitable for the implementation of computer-aided design systems for controlled digital
  Chebyshev low-pass filters of the first kind.

• ANALYSIS OF STABILITY AND FEATURES OF PRACTICAL IMPLEMENTATION OF HOGENAUER FILTERS AS RECURSIVE DIGITAL FILTERS WITH FINITE IMPULSE RESPONSE

  I.Е. Moiseenko , S. P. Tarasov , I.I. Turulin

  37-46

  2025-10-01

  Abstract ▼

  The article considers the issues of stability of cascade integrator-comb (CIC) filters used in digital signal processing, including decimation and interpolation. A brief review of modern publications on the architectural optimization of CIC filters is given. The main attention is paid to increasing the stability of filters to the overflow of the bit grid, analyzing their stability and the method of synthesis of recursive FIR filters (filters with a finite impulse response). For a better understanding of the nature of the stability of CIC filters, the paper presents mathematical calculations illustrating the features of the accumulation of the constant component for various block configurations. A change in the structure of the CIC filter is proposed, consisting in the permutation of the integrator and comb filter blocks. It is proved that such a change prevents the accumulation of the constant component of the signal in the integrators and, therefore, eliminates the overflow of the bit grid due to the accumulation of the constant component in the integrator. This approach is based on the property of linear filters, according to which changing the order of inclusion does not affect the transfer function. amplitude-frequency characteristic, but in the case of digital implementations it allows to significantly reduce the probability of overflow. The possibilities of hardware and software implementation of such structures are considered from the point of view of minimizing the loss of accuracy and increasing the reliability of digital signal processing systems. It is proposed to use integers or numbers with a fixed point to eliminate the accumulation of quantization errors. In addition, a program in Python was developed that implements a CIC filter taking into account the stability of the constant component in the input signal and the accurate execution of operations. The obtained results are compared with modern approaches presented in scientific research in recent years. The proposed solutions can be useful in developing digital filters for systems with limited computing resources and increased stability requirements.

• PRINTED LATTICES APPLICATION TO ELECTROMAGNETIC WAVES POLARIZATION CONTROL AT MICROWAVES

  А.О. Kasyanov

  38-60

  2025-07-31

  Abstract ▼

  The paper is devoted to consideration of variants of solution to some problems of diffraction
  for printed arrays with anisotropic inhomogeneities. The rotation of the plane of polarization is
  realized by means of a twist-reflector. On the basis of computational and full-scale experiments it
  was shown that twist reflectors based on microstrip reflective type antenna arrays (RAA) can be
  quite broadband. The obvious advantage of such twist-reflectors is simplicity of the technology of
  their manufacture, small thickness and weight. In addition, in twist-reflectors based on printed
  RAA, it is possible to constructively realize the necessary phase distributions of the field on their
  surfaces. Thus, it becomes possible to use such twist-reflectors to create phase-correcting twistreflectors.
  It is shown that introduction of impedance loads in the construction of the re-radiating
  elements of the printed RAA opens additional possibilities for controlling the field scattered by it.
  Thus, twist reflectors with improved characteristics can be realized on the basis of microstrip-pin
  RAA. The results of numerical studies based on the author algorithms and computational programs
  are presented. Besides, spatial polarizing filters and a controllable twist-reflectors based
  on microstrip RAA are considered. If microstrip elements of a twist-reflector contain controllable
  loads, then qualitatively new type of the microwave device is formed. This device enables to control
  polarization of the scattered field. Such devices can be named by polarizing modulators or
  manipulators. By means of printed RAA with elements of complex topology the spatial polarizers,
  which can transform electromagnetic waves with linear polarization in waves with rotating polarization
  and, in particular, in waves with circular polarization, are realized

• REDUCTION APPROACH OF TRANSIENT PROCESS OVERSHOOT IN CONTROLLED TUNABLE LOW PASS DIGITAL FILTER

  Al-Karawi Hussein Shakor Mogheer, I.I. Turulin

  2022-08-09

  Abstract ▼

  Digital signal processing is widely used in modern technology, including robotics, medical
  technology, etc. Thus, the controlled digital filters are used to eliminate the constant component of
  the output signal at the output of an analog-to-digital converter. This also reduces the low-frequency
  interference level spread out on the frequency axis to the left of the lower boundary of the signal
  spectrum. In actual situations, signals are subjected to a variety of disruptions and noises; however,
  applying a filter may suppress these noises and produce a clean signal. Controllability means the
  explicit dependence of the filter coefficients on the cutoff frequency. A transient occurrence can arise
  in a digital filter, which is indicated in the overshoot of the signal. A change in the cutoff frequency
  during filtering operation could cause this transient event. In this report, a Butterworth LPF filter is
  used to offer a compensation strategy for reducing this overshoot. A transient is an overshoot (drive)
  in the result timing chart. This drive is an after effect of the adjustment of the coefficients (boundaries)
  of the filter during filtering (this is classified "on-the-fly tuning"). 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).

• ANALYSIS OF CERTAIN WEIGHT FUNCTIONS (WINDOWS) AND THEIR APPROXIMATIONS FOR IMPLEMENTATION OF CONTROLLED RECURSIVE LOW-PASS FILTERS WITH A FINITE IMPULSE RESPONSE ON THEIR BASIS

  T.V. Shushkevich , А.А. Morozov, I. I. Turulin

  2021-11-14

  Abstract ▼

  There are various types of weighting functions, the so-called windows in digital signal processing,
  such as rectangular (Dirichlet window), triangular (Bartlett window), Vallee-Poussin window,
  Kaiser-Bessel window, Barsilon-Temesh window, Hann, Bohman, Blackman, Gauss (Weierstrass),
  Dolph - Chebyshev, Hamming windows and many others and ideal characteristics of standard filters
  such as low-pass, high-pass, bandpass filters. The purpose of this review article is to determine the most
  suitable weighting function for implementation on its basis of a controlled recursive low-pass filter with
  a finite impulse response. This article presents an analysis of only some of the above windows and their
  approximations, namely the Dolph - Chebyshev window, the Gauss (Weierstrass) window and the
  Hamming window. In addition to the analysis, the synthesis of recursive filters with a finite impulse
  response for weighting data based on the selected windows and their approximations was considered.
  The method of synthesis of Dolph-Chebyshev windows is considered. The implementation of the Gauss
  (Weierstrass) window is considered. Methods for approximating the Hamming window and methods
  and several algorithms for developing filters with FIR in the form of this window are considered. The
  estimation of parameters dependencies some quick window of the maximum level of the side lobes.
  Based on the data obtained, conclusions were drawn about the selection of the most suitable and
  demonstrating maximum performance windows, suitable for implementation on its basis of a controlled
  recursive low-pass filter with a finite impulse response.

• ANALYSIS OF MATLAB SYSTEM APPLICABILITY FOR SYNTHESIS OF CONTROLLED BUTTERWORTH DIGITAL RECURSIVE IIR FILTERS

  Hussein Sh. Mogheer, I. I. Turulin

  2021-08-11

  Abstract ▼

  A number of digital signal processing applications use controlled IIR digital recursive filters.
  The word " controlled " refers to filters whose structure ratios clearly depend on the cut rate or
  boundary frequencies. Controlled IIR filters can be synthesized using a variety of tools to compute
  traditional, uncontrolled IIR filters. The article dealt with the synthesis uncontrolled IIR filters and
  analyzed the suitability of the presentation of the results of synthesis for the construction of controlled
  IIR filters. The design techniques based on MATLAB (2021a) and the fundamental concepts of IIRButterworth
  digital filters were described and explained. The composited signal was processed by the
  analyzed filter to find whether it met the filtering progress criteria. To check the calculated filters, the
  Simulink prototype was used, as well as FDA tool of signal processing toolbox. Based on the results
  obtained, a conclusion was made about the applicability of the MAT LAB (2021a) system for the
  synthesis of controlled digital recursive IIR-Butterworth filters. The analyzed technique was more
  efficient, faster, decreased the tasks and found the results are satisfying.