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    How to convert s-parameter s21 to generate digital freq response with fixed fft bin

    Hi,
    I have a s21 complex frequency response. And it has 3001 frequency points to cover 28.7MHz(-14350000,14350000), each step is about 9566Hz. currently I want to convert the s21 response to digital spectrum with each fft bin size to be 30khz and sampling frequency to be 30.72MHz. I am thinking of interpolation of the s21 to higher frequency and then just purely decimate to 30.72MHz with purely decimation in frequency. But looks have to interpolate to a very high frequency due to 28.7MHz and 30.72mhz are not integer multiples, not sure if this is a correct way to do it. Can some one give me any suggestions? I really appreciate any suggestions.

    Thanks,
    squash

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  2. #2
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    Re: How to convert s-parameter s21 to generate digital freq response with fixed fft b

    Can some one give me any suggestions?
    Usually an interpolating function, preferably with smoothing behavior. Depends on the s21 shape, if its already smooth, you can just pick up points (resample) without interpolation.



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  3. #3
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    Re: How to convert s-parameter s21 to generate digital freq response with fixed fft b

    Quote Originally Posted by FvM View Post
    Usually an interpolating function, preferably with smoothing behavior. Depends on the s21 shape, if its already smooth, you can just pick up points (resample) without interpolation.
    Thank you for the point! I've been able to get it from resample function, I got impression resample is used for time domain signal. but actually it can also apply in frequency domain signal due to the shape of the frequency/time signal in my case.



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