Scientific and Technical Journal


ISSN Print 2221-3937
ISSN Online 2221-3805
The paper presents a method of synthesis of digital bandpass filters obtained on the basis of low-frequency prototypes with different impulse responses in the form of the characteristics of the "first type" and Gaussian bandpass filters. Impulse responses of Gaussian digital bandpass filter and "first type" filter are calculated using the method of dynamic transmission coefficient. Amplitude-frequency and phase-frequency characteristics are built for both types of digital filters: "first type" and Gaussian digital bandpass.
It is shown the dependence of change of the envelope of line by line calculation of response of digital bandpass filter of the "first type" and Gaussian digital bandpass filter: at the resonance frequency, within the band pass, outside the band pass. The resulting function of the envelope of Gaussian digital bandpass filter goes into steady state faster than the envelope of digital filter of the "first type". When calculating at the resonant frequency the envelope of Gaussian digital bandpass filter takes constant values for k=46, and the envelope of bandpass filter of the "first type" ― for k=66.
The results: it is shown, that Gaussian digital bandpass filter has advantages. Its impulse characteristic has "cooler" recession and reaches zero at 30% faster than the impulse characteristic with samples of impulse response of the "first type". It has lower inertia, its frequency response reaches zero faster, and within the boundaries of the values 43 ≤ k ≤ 23 it has more narrow "band", and therefore better noise reduction. Moreover, this filter allows to avoid errors arising due to the frequency range limitation.
It is shown, that to determine the dynamic characteristics of the digital filters after computing the impulse response samples a discrete Fourier transform matrix should be used. And dynamic transmission coefficient of Gaussian digital bandpass filter as a function of time for t → ∞ smoothly goes to the steady-state value.

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