6. 1 Concepts on Digital Filter o Digital Filter Specification o As in the case of the design of analog filters either the magnitude and/or the phase response is specified for the design of a digital filter for most application o In most practical applications the problem of interest is the development of a realizable approximation to a given magnitude response specification. The phase response of the filter can be corrected by cascading it with an allpass filter 2021年1月27日1时46分
2021年1月27日1时46分 6.1 Concepts on Digital Filter As in the case of the design of analog filters, either the magnitude and/or the phase response is specified for the design of a digital filter for most application. In most practical applications, the problem of interest is the development of a realizable approximation to a given magnitude response specification. The phase response of the filter can be corrected by cascading it with an allpass filter. ⚫ Digital Filter Specification
6. 1 Concepts on Digital Filter o We restrict our attention in this chapter to the magnitude approximation problem only We pointed out that there are four basic types of filters, whose magnitude responses are shown: 2021年1月27日1时46分
2021年1月27日1时46分 6.1 Concepts on Digital Filter We restrict our attention in this chapter to the magnitude approximation problem only. We pointed out that there are four basic types of filters, whose magnitude responses are shown:
低通 H(eJ 2 高通 e 带通 e 带阻 图6.1.1理想低通、髙通、带通、带阻滤波器幅度特性 2021年1月27日1时46分
2021年1月27日1时46分 图6.1.1 理想低通、高通、带通、带阻滤波器幅度特性 ( e ) j H ( e ) j H ( e ) j H ( e ) j H 0 低 通 0 高 通 0 带 通 0 带 阻 −2π −2π −2π −2π −π −π −π −π π π π π 2π 2π 2π 2π
6. 1 Concepts on Digital Filter o Since the impulse response corresponding to each of these is noncausal and of infinite length these ideal filters are not realizable o One way of developing a realizable approximation to these filters would be to truncate the impulse response for a lowpass filter 2021年1月27日1时46分
2021年1月27日1时46分 6.1 Concepts on Digital Filter Since the impulse response corresponding to each of these is noncausal and of infinite length, these ideal filters are not realizable. One way of developing a realizable approximation to these filters would be to truncate the impulse response for a lowpass filter
6. 1 Concepts on Digital Filter o The magnitude response specifications of a digital filter in passband and in the stopband are given with some acceptable tolerances o a transition band is specified between the passband and the stopband to permit the magnitude to drop off smoothly o For example the magnitude of a losspass filter may be given as shown in Figure 9.1 2021年1月27日1时46分
2021年1月27日1时46分 6.1 Concepts on Digital Filter A transition band is specified between the passband and the stopband to permit the magnitude to drop off smoothly. The magnitude response specifications of a digital filter in passband and in the stopband are given with some acceptable tolerances. For example, the magnitude of a losspass filter may be given as shown in Figure 9.1