From help-octave-request at bevo dot che dot wisc dot edu Fri Dec 7 10:41:01 2001 Subject: Re: need help filtering a signal From: Shengchao Li To: Philipp Schwaha cc: help-octave at bevo dot che dot wisc dot edu Date: Fri, 7 Dec 2001 11:40:50 -0500 (EST) their is frequency associated with the fft result. It depends on what is your sampling rate. You need to give us 1. the sampling rate (how many samples per second) 2. how long your trunk of data is 3. the frequency range of your signal before we can find out the frequency in your fft output. shengchao On Fri, 7 Dec 2001, Philipp Schwaha wrote: > hi! > > what i need to do is fiter a signal to remove noise. what i wanted to try > first was a fft then cut all frequencies except the the important ones (e.g > 100Hz, 200Hz ...), but when i did the fft i did not know how to do this, > since there are no frequencies associated with the values the function fft > returns. > this is the first time i try to do something using an fft. > then i discovered the function fftfilter, but i could not make it produce the > results i wanted. > > how can i remove all frequencies from a certain signal, except a few selected > ones? > > thanks > philipp > > > > ------------------------------------------------------------- > Octave is freely available under the terms of the GNU GPL. > > Octave's home on the web: http://www.octave.org > How to fund new projects: http://www.octave.org/funding.html > Subscription information: http://www.octave.org/archive.html > ------------------------------------------------------------- > > ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html -------------------------------------------------------------