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Digital Filter Specification3/20/2021
RPSGT Prep Time 780 terms ZackFreeman2 NEW RPSGT EXAM- 2018 Study Guide and Pra 999 terms MelanieRodger RPSGT 321 terms Kristenelena27 PSG - A and P, etc.Practical band-stop filters introduce transition bands adjacent to frequncies which determine the stop band.The specification is developed based on the technical requirements to the filter and the possibility of hardware realization.
The frequency ranges in which signals pass through are named filter pass-band, and frequency ranges in which signals are rejected are named stop-band. In practical filters, signals attenuate in the pass-band as well as in the stop-band. The signal attenuations in the pass-band should not exceed some low level. In the stop-band, signal attenuations must not be smaller than the determined level. There are four basic types of filter specifications, one for each of the four basic filter types: low-pass, high-pass, band-pass and band-stop. Generally, filter specifications determine pass band and stop band frequency ranges, desirable signal attenuations (gains) at those ranges, approximation methods for the filter design, and hardware implementation requirements. Ideal low-pass filters are unrealizable due to the fact that when frequencies change from pass band to the stop band, the gain(reflection) is a jump that results in a discontinuous transition. Practical low-pass filter specifications specify the transition band where filter gain (attenuation) continuously changes from pass band gain to stop band gain. Pass band edge frequency describes a frequency below which the signal must pass through a filter with attenuation that does not exceed. Usually, the attenuation in the pass band changes in the range. All frequency components above stop band edge frequency must be attenuated. The attenuation for high quality low-pass filters can be 60 - 80 db. The behavior of the system in the transition band is not specified. The shorter the transition band, the better the practical filter is. Ideal high-pass filters are unrealizable due to the fact that when frequencies change from stop band to the pass band, the gain(attenuation) is a jump that results in a discontinuous transition. Practical high-pass filters specify the transition band where filter gain (attenuation) continuously changes from stop band gain to pass band gain. The attenuation for high quality high-pass filters must be at least 60 - 80 db. All frequency components above pass band edge frequency Fp must pass well. Usually, pass band attenuations for practical filters do not exceed 1 db. Since ideal filters can not be realized in hardware, practical bandpass filters introduce transition ranges adjacent to the frequncies which determine pass band. The pass band is determined by edge frequencies Fp1, Fp2 and pass band attenuation Ap. The left stop band is determined by attenuation As1 applied to the frequencies in the range 0 Fs2.
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