DIGITAL CHEBYSHEV FILTER DESIGN

Chebishev filters are analog or digital filters.they have ripples in passband or stop band depending upon their type.

There are two types of filters:
a) Type 1
b) Type 2 

Type 1:  
It has steeper roll-off in stop band, whereas passband has ripples
  
Type 2: 
Type 2 is exactly opposite to type1.Response is flat in passband and ripples cain in stop band.

   
 Figure above shows the response of type1 and type2 chebyshev filter .


Ripples for odd and even order of filter is shown .

We performed Type I low pass filter using Scilab. We first designed analog filter from the inputs and then designed digital filter from the analog filter. Attenuation in passband and stopband(AS,AP), passband and stopband frequencies(fS,fP) and sampling frequency(FS) were taken as inputs and we used to get magnitude spectrum and pole-zero plot for both analog and digital filter.

We observed that as we increase the order of filter, the ripples in passband reduce and we get more idealized characteristics. As all poles were inside the unit circle, the filter designed was stable.

https://drive.google.com/drive/folders/0BwJUrR8ne7NkNDhQU201cnlCZ0E