Sunday, 23 April 2017

DSPP Experiment 5 : Butterworth Filter Design

This was the first experiment where we used Scilab for implementing the code. It's an open source tool for simulation. I had used Matlab earlier so I was quite comfortable using Scilab, as it is similar. Of course, if you're willing to spend some money, then MATLAB is a better software. But one should always be familiar with open source tools.
In this experiment, we wrote a code in Scilab to design a Butterworth filter wherein the various parameters like pass band attenuation, stop band attenuation, pass band frequency, stop band frequency and sampling frequency are passed as input and the order of the filter as well as its cutoff frequency is calculated. The order of filters in practical systems is very high for a desired response.

The normalized transfer function is evaluated according to the filter type,i.e LPF or HPF(replacing s by 1/s). From the normalized transfer function, the transfer function of the filter was calculated in the Laplace (s) domain and then converted to the Z domain by using the Bilinear Transform Method.
We concluded that the response by simulation was very close to the desired one and the order was high for most of the designs.

19 comments:

  1. Due to its higher order its hardware implementation is difficult.

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    Replies
    1. Yes, Butterworth filters generally have higher order

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  2. No ripples in Butterworth filter

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    Replies
    1. Yes, generally there are no ripples in Butterworth filter

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  3. Butterworth filter is monotonic in nature.

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    Replies
    1. Yes, Butterworth filter is monotonic in nature

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  4. butterworth filter has no ripples

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    Replies
    1. Yes, generally there are no ripples in Butterworth filter

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  5. The Butterworth filter is a type of signal processing filter designed to have as flat a frequency response as possible in the passband.

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  6. In Butterworth filter as we go on increasing order of filter, response becomes more sharper and at approaches to ideal response.

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    Replies
    1. Yes, the order is generally higher in Butterworth filter

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  7. It does not give a sharp response but gives perfectly flat passband

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    1. Yes, hence it is preferred for higher end applications

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  8. It has less ripples as compared to Chebyshev filters

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    Replies
    1. Yes, it has no ripples in pass band and stop band

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  9. In Butterworth filter,the transition band becomes sharper as the order increases.

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