Filtry dolnoprzepustowe i filtry składowej stałej o zmiennych parametrach

• Autorzy: Kaszyński R.

Warianty tytułu

EN

Low-pass and constant component filters with variable parameters

• Języki publikacji: PL

Abstrakty

EN

Analog low-pass and constant component filters are used as terms for preliminary averaging or bounding the spectra of signals designated for further processing in the digital technique. All analog filters are featured by a transient state of the output signal. According to the indefiniteness principle the lowering of the filter pass-band results in the lengthening of the transient state. Analysis and examination of properties of filters with constant parameters allow to draw a conclusion that replacement of the constant parameters by time-varying functions leads to a shortening of the transient state with a-accuracy. The presented concept of varying the parameters in low-pass and constant component filters allow to preserve time-invariance of output signals as well as stability of systems. A filter performance criterion is formulated which takes into consideration transient states and spectral properties especially useful in assessment of filters with variable parameters. The carried out simulations of low-pass Butterworth, Chebyschew and Legendre filters followed by an exhaustive analysis of the results allow to define functions omega(Oi)(t), beta(i)(t), T(t) for varying the filter parameters which guarantee substantial shortening of transient states of filtered signals. Additionally, an introduction of non-zero initial states may in special cases lead to shortening the transient state. An effect of additional narrowing of the spectrum has been discovered which, when applied to filters of the constant component with variable parameters, allows to shorten the settling time with simultaneous narrowing of the filtered signal spectrum and as a consequence lowering the presence of variable components in that signal. Using the effect of additional narrowing of the spectrum one has worked out a constant component filter with variable parameters which, at the same time, gains a substantial shortening of the settling time. Based on the proposed filter performance criterion a comparison of variable parameters filters with appropriate constant parameters ones has Been done. This comparison reveals much better properties of variable parameters filters (the filter performance criterion is many times less). A very big influence of the effect of additional narrowing of the spectrum on the filtration quality has Been confirmed by examples. An application of the constant component filter with variable parameters to averaging the brainstem auditory evoked potentials has been demonstrated.

Słowa kluczowe

PL

filtry analogowe; filtracja sygnałów; przetwarzanie sygnałów

• Wydawca: Wydawnictwo Uczelniane Politechniki Szczecińskiej
• Czasopismo: Prace Naukowe Politechniki Szczecińskiej. Instytut Automatyki Przemysłowej
• Rocznik: 2001
• Tom: Nr 569(19)
• Strony: 5--183
• Opis fizyczny: Bibliogr. 268 poz., tab., rys.

Twórcy

autor

Kaszyński R.