ONE query on PHASE RESPONSE.........

[rajhere]

Hi all,
i m working on IIR filter by using BILINEAR TRASNSFORMATION method...

Can anyone pls tell me the significance of phase/freq response in general......

significance in terms of what all innformation we can capture by seeing the phase response waveform.....

And also coparision with other methods like Impulse Invariance method, method of approximate derivates.......


regards
rajhere

 

[xulfee]

phase responce and magnitude responce are combinly used to locate poles n zeros,generally speaking i think bilinear transformation is general method to go from analog domain to digital where others may've some conditions

 

[Kral]

raghere,
A frequent application of filters is to provide frequency selection, where one band of frequencies must be passed, and other band(s) of frequencies must be rejected.
.
There are two applications in which phase response is important.
.
1) Applications such as control systems in which negative feedback is used. In this case the phase response will affect the stability of the system
.
2) Applications in which the waveform of a signal must be preserved. In these applications, the filter must have the linear phase propeerty. In a linear phase filter the phase shift is directly proportional to (a linear function of) frequency.
.
One must be careful when using the bilinear transform because the phase characteristics of the analog prototype, to which the transform is applied, are not preserved by the bilinear transformation. Other transforms, such as the impulse invariant ransform have phase characteristics that closely match those of the analog protoype as long as the frequencies of interest are considerably below the Nyquist frequency (1/2 the sampling frequency).
.
Regards,
Kral