V.V. Afanasyev - Dr.Sc. (Eng.), Professor, Department of «Radioelectronic and Quantum Devices» Kazan National Research Technical University named after A.N. Tupolev (KNRTU-KAI). E-mail: nsdx@yandex.ru E.R. Mardanshin - Post-graduate Student, Department of «Radioelectronic and Quantum Devices» Kazan National Research Technical University named after A.N. Tupolev (KNRTU-KAI). E-mail: m.emil89@mail.ru

Increasing of accuracy and reliability of multichannel measurement system is inextricably linked with suppression of the complex noise and interference operating in actual practice operation. In multichannel low-frequency onboard measurement systems with time division of information channels, of information signals have the form of rectangular impulses with a priori unknown amplitude. To suppress noise and interference the low pass filters (LPF) are widely applied, in which increasing suppression with increasing time constant of the LPF inevitably leads to the increase of the distortion of the shape of channel signals. There are methods of selective suppression interference in the form based on the principle of two- channels of the theory of invariance for required suppression of interference when the allowable distortion of signals and based of this methods the parametric notch filters (PNF) are synthesized which provide noise rejection while reducing distortion of pulse signals of known shape. The purpose - is a comparative study of noise suppression and distortion of signals by parametric notch filters with the optimization of parameters for notch devices when noise reduction is performed in measuring systems with time division of channels. The evaluation of the suppression ratio of the input pulse signal by varying the sampling of signals based on simulations of PNF using packages Workbench and MathCad was conducted. For PNF the recommended range of the number of counts within rectangular pulse is from 300 to 500. Experimental studies was were conducted to evaluate the efficiency of PNF compared with standard single-link LPF. Study of a model with identical distortions of a pulse signal by the filter showed that the error of measurement of the amplitude of the output pulse signal at the lower operating frequency is reduced to not less than 80%, at the central operating frequency is reduced to not less than 27%, and at the upper operating frequency is reduced to not less than 10% under the influence of narrowband interference compared with the LPF. Therefore, for the same distortion signals the degree of noise suppression in PNF is higher than in the LPF and efficacy of PNF increases with decreasing frequency interference. Conclusions. Parametric notch filters are have more complex circuitry, but are more efficient and allow reduction of noise while reducing distortion of pulse signals compared to the standard filter circuits. The error of measurement of the amplitude of the output pulse signal at the lower operating frequency is reduced to not less than 80%, at the central operating frequency is reduced to not less than 27%, at the upper operating frequency is reduced to not less than 10% under the influence of narrowband interference compared with the LPF with identical distortions pulse signal by filter. The use of PNF is most effective for suppressing low-frequency noise and interference in measuring systems with time division of channels for signals of rectangular shape. The work was done Iin the framework of task No. 11.34.214/ on execution of public works in the scientific activity sphere the work was done.

 

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