MATLAB BUILDER EX 1 Guía de usuario descargar pdf (Pagina 71)

Spectral Analysis Example

4-19

powerspect = [];

return;

end

if (interval <= 0)

error('Sampling interval must be greater then zero');

return;

end

fftdata = fft(data);

freq = (0:length(fftdata)-1)/(length(fftdata)*interval);

powerspect = abs(fftdata)/(sqrt(length(fftdata)));

plotfft.m:

function [fftdata, freq, powerspect] = plotfft(data, interval)

[fftdata, freq, powerspect] = computefft(data, interval);

len = length(fftdata);

if (len <= 0)

return;

end

t = 0:interval:(len-1)*interval;

subplot(2,1,1), plot(t, data)

xlabel('Time'), grid on

title('Time domain signal')

subplot(2,1,2), plot(freq(1:len/2), powerspect(1:len/2))

xlabel('Frequency (Hz)'), grid on

title('Power spectral density')

To proceed with the actual building of the component, follow these steps:

1 Start mxltool. See “Graphical User Interface Menus” on page 2-2 for a

discussion of using

mxltool to build a COM component from a collection of

MATLAB M-files.

2 Create a new project with these settings:

•

Component name: Fourier

• Class name: Fourier

• Project version: 1.0

Check Use Handle Graphics library.

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MATLAB BUILDER EX 1 Guía de usuario Pagina 71