spectrogram
in [Matlab]
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From: Atul Ingle on 30 Jun 2010 19:07 Have you tried using spectrogram() with the 'F' vector input which makes it calculate the STFT at only those frequencies you want? "Martin " <martin.bruha(a)gmail.com> wrote in message <hs4i1g$bgd$1(a)fred.mathworks.com>... > Hi everyone > > I need a help with 'spectrogram' function. It makes FFT of my signal and plots it with time and frequency on the axis and the magnitude of frequency showed with color. > The frequency range of FFT algorithm depends on the sampling frequency. > In my case the sampling frequency is very high (160 kHz), but as the result I focus just on the range 0-60 Hz. Can I modify spectrogram to compute the fft only up to 60 Hz? > I can change the range in Axes properties but in this way I loose the information of magnitude (displayed with color) because I just cut a very small piece from wide frequency range > > Thank you for your help and tips. > > Martin Bruha
From: Wayne King on 30 Jun 2010 19:32 "Martin " <martin.bruha(a)gmail.com> wrote in message <hs4i1g$bgd$1(a)fred.mathworks.com>... > Hi everyone > > I need a help with 'spectrogram' function. It makes FFT of my signal and plots it with time and frequency on the axis and the magnitude of frequency showed with color. > The frequency range of FFT algorithm depends on the sampling frequency. > In my case the sampling frequency is very high (160 kHz), but as the result I focus just on the range 0-60 Hz. Can I modify spectrogram to compute the fft only up to 60 Hz? > I can change the range in Axes properties but in this way I loose the information of magnitude (displayed with color) because I just cut a very small piece from wide frequency range > > Thank you for your help and tips. > > Martin Bruha Hi Martin, In addition to Atul's suggestion, if it is just a matter of display, you can always scale the color axis. See the documentation for caxis. Wayne In addition to
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