DSPP Experiment 7 : Design of FIR filter using Windowing Method

In experiment 5 & 6, we designed IIR filters viz. Butterworth Filter and Chebyshev Filter. IIR filters are not stable due their recursive nature. Also, they have non-linear phase response hence, the output of the filter appears to be distorted version of the input. What can be done to avoid this? Use FIR filters!

These are filters that have a Finite Impulse Response. and hence, output of the filter is the phase shifted input signal. Also, since they don't have any feedback, the filters are very stable. However, this requires large memory as compared to IIR filters.

There are two methods of designing FIR filters. One of them is using Windowing Method. In this method, a particular window function is chosen on the basis of the attenuation required in the stop band. 

We used a Hanning Window as the window function and wrote the code accordingly. During execution, the filter parameters like the attenuation and frequencies were given as user input similar to IIR filter design. The plot function was used to verify the response of the designed filter. A notable difference between IIR and FIR designing is that much of the calculation is done in time domain rather than the transform domain.