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Homework Help: How to interpolate with a FIR filter

  1. Sep 28, 2007 #1
    1. The problem statement, all variables and given/known data

    I have a signal that I want to interpolate 625 times, and then decimate 12 times to get the decired result. I've read that the best way of doing this is to use a polyphase FIR filter with zero stuffing. I was planning to use steps of 5 for the interpolation, and steps of 4 at the decimation. The problem is that I'm kind of new to digital signal processing, so I don't know how to find the coeffisients for the FIR filter. I have downloaded ScopeFIR, a program that can generate FIR filter coeffisients, but there are several parameters that I have to set:

    -What type of filter: Simple Parks-McClellan, Advanced Parks-McClellan, Windowed Sinc, Raised Cosine, Lth-Band (Nyquist), Inport/Boxcar, Maximally Flat, CIC

    -Passband upper frequency

    -Stopband lower frequency

    -Passband ripple

    -Stopband Attenuation

    I would be very grateful if someone could help me with these parameters, or give me a guide for finding these coeffisients in another way!

    2. Relevant equations

    3. The attempt at a solution

    I've read an enormous amount of webpages regarding this, but I just don't understand it. I have already done the programming of the filter, the only problem is finding thos coeffisients.
    Last edited: Sep 28, 2007
  2. jcsd
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