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• 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.

• STABILITY OF WALKING MACHINES AND ROBOTS IN UNDERWATER CONDITIONS

  V.V. Chernyshev, I.P. Vershinina, V.V. Arykantsev

  2020-07-10

  Abstract ▼

  When carrying out underwater technical works, walking machines and robots moving along the bottom significantly surpass traditional vehicles in terms of traction and cross-country ability. The exploitation conditions of underwater walking robotic systems - a rough terrain of the seabed, slopes, weakly bearing soil, etc., determine the urgency of the problem of their stability. The paperdiscusses the results of theoretical and experimental studies aimed at ensuring the dynamic stabil-ity of walking machines and robots in underwater conditions. The novelty of the study is provided by the specific features of their operating conditions. The studies are based on the test results of the 6-legged underwater walking device MAK-1. The instability of the walking device may be caused by the gait features. Also, the loss of stability of the walking device can occur when meet-ing with an unrecognized obstacle and when overcoming slopes. Mathematical modeling of the dynamics of statically unstable gait is carried out. The main stages of the phase of movement of the device in an unstable position are analyzed. It is shown that underwater conditions, dynami-cally stable walking of a 6-legged walking device with cyclic movers is also possible in the case of independent legs drives of the right and left side. The methods of autonomous response to a meet-ing with an unrecognized obstacle are considered. Various typical situations that arise when mov-ing along an unorganized surface are analyzed. The methods of self-adaptation and self-management of legs based on fuzzy algorithms, that exclude the occurrence of emergency situa-tions, including rollover, are proposed. The features of overcoming slopes by walking vehicles in underwater conditions are considered. In traditional vehicles movement, rollover or slide downhill is possible. It is shown that on weak soils downhill slide of walking machine is unlikely. This is due to significant deformations of the soil under the supporting elements (feet) of walking machines. A method of increasing the resistance to tipping over when moving a walking device along a slope due to the separate tuning of the conditional clearance of the walking mechanisms is considered. Particular attention is paid to the stability of drilling walking platforms moving along the bottom. Their specificity is the high location of the center of mass. Possible stages of walking platforms rollover are considered. The stabilizing effect of an increased location of the center of floatation is shown. The results of the work can be demanded in the development of walking machines and robots designed for underwater technical works, for new industrial technologies for the develop-ment of the seabed resources, to ensure the antiterrorist and technological safety of underwater infrastructure objects and other works.

• PHOTODETECTOR WITH CONTROLLED RELOCATION: DRIFT-DIFFUSION MODEL AND APPLICATION IN OPTICAL INTERCONNECTIONS

  I.V. Pisarenko, Е.А. Ryndin

  2020-07-20

  Abstract ▼

  Previously, we proposed an injection laser with a double AIIIBV nanoheterostructure for the
  generation and modulation of light in optical interconnections for integrated circuits. To convert
  short optical pulses generated by the laser-modulator into electrical signals, a technologically
  compatible photodetector with subpicosecond response time is needed. Traditional designs of
  photosensitive semiconductor devices do not meet the specified requirements. Therefore, we developed
  a promising concept of a high-speed photodetector with controlled relocation of carrier density
  peaks within specially organized quantum regions. This optoelectronic device includes a longitudinal
  photosensitive p-i-n junction and a transverse control heterostructure, which containstwo low-temperature-grown layers and two control junctions. Before the trail of an optical pulse,
  the photodetector operates as a classical p-i-n photodiode. Transverse electric field is activated
  only during the back edge of a laser pulse. It relocates the peaks of electron and hole densities
  from the absorbing region to the regions with low carrier mobility and short lifetime. This process
  leads to the decrease in response time to a subpicosecond value. In our previous papers, we estimated
  the performance of the considered device using a quantum mechanical combined model that
  had not taken into account certain aspects of charge carrier transport in its structure. This paper
  is aimed at a proper semiclassical analysis of transients in the photodetector with controlled relocation
  by means of a two-dimensional drift-diffusion model. For the numerical implementation of
  the model, we develop a finite difference simulation technique based on the explicit method and
  applied software. According to the obtained results, it is reasonable to use the differential connection
  principle in order to compensate displacement currents in the supply circuit of the device. In
  view of this feature, we propose a circuit of optical receiver that provides the generation of resultant
  electrical signal as well as the required mode of the control voltage application to the
  photodetector contacts, and a driver circuit for the lasers-modulators.

• DECIMETER RANGE GENERATOR

  A. N. Zikiy, A. S. Kochubey

  2021-07-18

  Abstract ▼

  The receiver's heterodyne and the transmitter's master oscillator are the most important
  components, as they determine their stability and range properties. In recent years, the Meteor
  plant has created a number of new voltage-controlled generator chips with high electrical parameters.
  However, the advertising materials of this company do not contain a number of parameters
  that are important from the point of view of the consumer. Therefore, the purpose of this work
  is to study the main characteristics of the generator, including those not declared by the supplier:
  the width of the signal spectrum, the average steepness of the modulation characteristic, the level
  of harmonics. The object of the study is the GUN382 microchip in a typical switching circuit.
  The results of an experimental study of a VCO operating in the 1200 MHz region are presented.
  The estimation of parasitic products in the spectrum of the output signal is given. Photos of the
  spectrum of the output signal showing a small width of the spectral line are presented. The modulation
  characteristics are measured when the control voltage and supply voltage change, and their
  average steepness is calculated. These data allow us to make reasonable requirements for the
  stability of the control and supply voltages. The results obtained can be used in receiving and
  transmitting equipment for communication, navigation, and electronic warfare. The article expands
  the idea of the line of generators of the Meteor plant, demonstrates their high electrical
  characteristics: operating frequency range 1200 ± 16 MHz; output power of at least 1 dBm; supply
  voltage + 5V; control voltage from 0 to 8 V; the level of the second and third harmonics does
  not exceed minus 22 dB in relation to the useful signal.

• MASTER GENERATOR OF CENTIMETER-WAVE INTERFERENCE TRANSMITTER

  A.N. Zikiy , A.S. Kochubey

  2021-08-11

  Abstract ▼

  The master generator of the transmitter is the most important component, since it determines
  its stability and range properties. In the Russian market there are many models of auto generators
  of domestic and foreign production. They differ in the element base (active element),
  weight, dimensions, cost, operating frequency range, and other parameters. In many cases, the
  passport and technical specifications do not contain a number of parameters that are important
  for the consumer. The purpose of this work is to study the main characteristics of the generator,
  including those not declared by the supplier. The object of the study is a microwave generator
  module in a typical switching scheme. The results of an experimental study of a VCO operating in
  the 5 GHz region are presented. The estimation of parasitic products in the spectrum of the output
  signal is given. Photos of the spectrum of the output signal showing a small width of the spectral
  line are presented. The modulation characteristics are measured when the control voltage and
  supply voltage change, and their average steepness is calculated. These data allow us to make
  reasonable requirements for the stability of the control and supply voltages. The results obtained
  can be used in receiving and transmitting equipment for communication, navigation, and electronic
  warfare. The article expands the idea of the line of domestic generators, demonstrates their highelectrical characteristics. The following electrical parameters have been achieved: – operating
  frequency range from 4968 to 5448 MHz; – output power of at least 11 dBm; – supply voltage
  minus 16 V; – control voltage from 5 to 31.5 V.

• 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.

• 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).