setting coefficients of particular frequency components to zero
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Hello,
How to set the set the coefficients of particular frequency components to zero of a signal(for example coeffcients of from 1) 0.2Hz to 0.5Hz 2)0.8 to 6Hz frequency components coefficients to zero.
How to convert bakc iti into time domain after removing the frequency compoents coefficients.
Can I someone explain this with an example.
Thanks.
4 Kommentare
Star Strider
am 6 Aug. 2014
You need to design two separate notch filters, then cascade them. Your resulting digital filter will filter them in the time domain, so no conversion back to the time domain will be necessary. See the documentation for the Signal Processing Toolbox for details.
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Chad Greene
am 6 Aug. 2014
fs = 10; % Hz sampling rate (I made this up, you need to fix it)
filteredSignal = bandstop_butterworth(signal_data,[.2 .5],fs,1);
plot(signal_data,'b')
hold on
plot(filteredSignal,'r')
7 Kommentare
Chad Greene
am 6 Aug. 2014
I can't think of any physically-reasonable methods. Think about a mass oscillating on a spring. It naturally wants to make smooth arcs as it swings, and it would take energy to stop or sharply divert the mass as it moves. Your signal abruptly stops at y=0 as if someone put energy into stopping a mass. If you remove some frequency energy from your signal you'll essentially be taking away some of the energy that it would take to stop a swinging mass. If you want a brute-force method of keeping a filtered signal from going to zero, you can end the lines of code you've already created with
finalsignal(finalsignal<0)=0;
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