| Mu Analysis and Synthesis Toolbox | Search Help Desk |
| mfilter | Examples |
Generate SYSTEM representations of a Bessel, Butterworth, Chebyshev or RC filter
Syntax
sys=mfilter(fc,ord,type,psbndr)
Description
Calculates, as a SYSTEM, a single-input, single-output analog low-pass filter. These filters are often encountered in experimental arrangements and must be accounted for in experimental data processing and control design. For more sophisticated filterssee the Signal Processing Toolbox functions.
The cutoff frequency (Hertz) is fc and the filter order is ord. The string variable, type, specifies the type of filter and can be one of the following. |
Butterworth |
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Chebyshev |
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Bessel |
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series of resistor/capacitor filters |
psbndr specifies the Chebyshev passband ripple (in dB). At the cutoff frequency, the magnitude is -psbndr dB. For even order Chebyshev filters the DC gain is also -psbndr dB.
The Bessel filters are calculated using the recursive polynomial formula. This is poorly conditioned for high order filters (order > 8).
Examples
butw =mfilter(2,4,'butterw'); cheb =mfilter(4,4,'cheby',0.5); rc =mfilter(1,4,'rc'); omega = logspace(-1,2,100); butw_g =frsp(butw,omega); cheb_g =frsp(cheb,omega); rc_g =frsp(rc,omega);vplot('bode_gl',[.1 100 .001 10],[.1 100 -180 180],... butw_g,'-',cheb_g,'-',rc_g,'-.') subplot(211),title('Butterworth, RC Chebyshev Filters')
