Saturday, 23 April 2016

Chebyshev Filter Design

The objective of this experiment was to design a digital chebyshev filter from analog chebyshev filter
       In this experiment we have taken inputs like pass band attenuation, stop band attenuation, pass band, stop band and sampling frequencies in hertz. We implemented calculations of all parameters of the chebyshev filter in scilab. following conclusions were obtained from this experiment

  1. If the order of the filter is say five (N=5) then in the magnitude plot of the filter number of ripple peaks represents order of the filter i.e spectrum will have 5 ripple points.
  2. the magnitude spectrum is equi-ripple in passband and monotonic in stopband  where as in butterworth its is opposite.
  3. there is a difference in values observed and calculated (theoretical) of Ap and As because of variations in constant values and inaccuracies .
the image below represents the spectrum of a low pass chebyshev filter with order (N) =6



- As we can see there is a ripple of around 20% in this plot ad 6 ripple points represents order=6.

scilab code for Chebyshev filter design :
https://drive.google.com/open?id=0B-US8fsfaFQxYWc1S2lNaWNFY0E

2 comments:

  1. Poles are inside the unit circle thus filters are stable(HPF and LPF)

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