how can i filtering white gaussian noise using shaping filter H(f)

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Good mind 2017-4-16

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评论： Star Strider 2017-4-19

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i want filtering white gaussian noise using shaping filter h(f). what is the function of shaping filter in matlab

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Answer 1

Star Strider 2017-4-16

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Define the filter as a designfilt object (if you use designfilt), as numerator and denominator polynomials, or preferably a second-order-section and gain matrix, then use the filtfilt function to filter it, as you would any other signal. Your filter will pass the selected random-amplitude values in the frequency spectrum you specify for the filter. You can see the results if you do a fft (link) on the output of the filter.

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Star Strider 2017-4-17

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My pleasure.

I understand that you want to add band-limited white noise to your signal. The filter design procedure is the same.

To design a bandpass filter with a lower passband frequency of 60 Hz and an upper passband frequency of 120 Hz, you can use this design. Your EKG signal has to have a sampling frequency of at least 250 Hz for this filter to work. Be sure to use the sampling frequency of your signal, if it is not 250 Hz as this filter was designed for:

Fs = 250;                                               % Sampling Frequency
Fn = Fs/2;                                              % Nyquist Frequency
Wp = [60  120]/Fn;                                      % Passband Frequencies (Normalized)
Ws = [59  121]/Fn;                                      % Stopband Frequencies (Normalized)
Rp = 10;                                                % Passband Ripple (dB)
Rs = 50;                                                % Stopband Ripple (dB)
[n,Ws] = cheb2ord(Wp,Ws,Rp,Rs);                         % Filter Order
[c,b,a] = cheby2(n,Rs,Ws);                              % Filter Design
[sosbp,gbp] = zp2sos(c,b,a);                            % Convert To Second-Order-Section For Stability
figure(1)
freqz(sosbp, 2^16, Fs)                                  % Bode Plot Of Filter

Use the filtfilt function to do the actual filtering.

The freqz call is not necessary for the code. It shows you what the filter passband and stopband will look like in the frequency domain, so you can be certain it is stable and gives you the result you want. Other designs such as the Butterworth designs are also possible with this code, although you have to increase the transition regions (the frequency differences between the stopbands and passbands) to use other designs to get stable filters.

Good mind 2017-4-19