In this experiment a scilab code was developed to design a digital Chebyshev filter by accepting the following specifications
- Pass band attenuation(Ap<3dB)
- Pass band frequency(Fp in Hz)
- Stop band attenuation(As>40dB)
- Stop band frequency(Fs in Hz)
- Sampling frequency(Fs in Hz)
The analog Chebyshev filter was designed from the above specifications and then digital filter was obtained by BLT method.The magnitude response for the designed filter was obtained and the values of As and Ap were calculated from the response. The values were close to each other. Also from the magnitude response it was observed that there are ripples in the passband of the filter, The number of ripples depends on the order of the filter.
The pole zero plot of the transfer functions of both analog and digital frequency was obtained. For LPF the analog filter poles are on the LHS of the imaginary axis whereas digital poles were on the RHS of the imaginary. Also the digital filter were inside the unit circle.
try a 96th order filter , the spectrum becomes almost like an ideal filter
ReplyDeleteSure will try tha
Delete*that
DeleteIn chebyshev the order of filter is less as compared to butterworth
ReplyDelete@Chinmay and @Kartik u can try making another program for that!
ReplyDeleteWe'll surely try that... after all we do like to observe ideal characteristics even though we barely get to see them... :p
Deletewe observe ripple in stopband.
ReplyDeleteA lower order means less hardware(delay blocks) required which lowers cost. The trade off is with quality. So the headphones you get on stations may have this, or worse, an elliptical filter :P
ReplyDeleteThat's some deduction "SR" ... will surely buy branded one next time onwards.
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