MATLAB: Cheby1

cheby1

Hi, I'm having problems finding something out something simple.

If I'm given this: –

[b,a] = cheby1(8,1,0.4); 
y = filter(b,a,x);

then what do the three digits in the brackets after 'cheby1' mean?

Also what does b, a and x mean?

Many thanks,

Tom

Best Answer

Chebyshev Type 1 filter design

http://www.mathworks.com/help/toolbox/signal/ref/cheby1.html

1-D digital filter

http://www.mathworks.com/help/techdoc/ref/filter.html

Related Solutions

MATLAB: What is the difference between “fdesign” and “fir”

d = fdesign.response(spec)

defines a particular filter specification. Based on that specification, if you do

myFilter = design(d)

you will get a filter which you can used to filter a signal by invoking

y = filter(myFilter,x)

This approach allows you to choose among eligible design methods at the design stage.

On the other hand,

b = fir1(n,Wn,'ftype',window)

is specifically for designing an FIR filter using window method, so you have to know that you want to use that particular method before you design that filter. What you get is simply the filter coefficients for the resulting FIR filter and you can use that to filter the signal via

y = filter(b,1,x)

If you happen to choose to design an FIR filter using window method in the fdesign approach, then you should get equivalent filters.

HTH

MATLAB: Fir and iir filtering

You have to know your filter specifications. If you do, you can do both with fdesign.lowpass and fdesign.highpass

fdesign.lowpass and fdesign.highpass have different specification strings which support different filter designs.

The default string 'Fp,Fst,Ap,Ast' supports both FIR and IIR designs.

Here is an example:

Design a lowpass filter with a passband frequency of 1 kHz, a stopband frequency of 1.5 kHz, passband ripple of 0.5 dB, and stopband attenuation of 40 dB. The sampling frequency is 20 kHz

   d = fdesign.lowpass('Fp,Fst,Ap,Ast',1e3,1.5e3,0.5,40,20e3);
   designmethods(d)  %shows which designs are valid for this spec
   Hdeq = design(d,'equiripple'); % FIR filter
   Hbutt = design(d,'butter'); %IIR design

Best Answer

Related Solutions

MATLAB: What is the difference between “fdesign” and “fir”

MATLAB: Fir and iir filtering

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