Well, apart from gwenhwyfaer's point that the spectrum is equivalent to a sawtooth hard-sync'ed to the FFT period and the general advice to use proper windows for analysis, the only thing I can recommend is to simply oversample the FFTs via zero-padding when doing this kind of analysis. In that way you get enough resolution that you should always see the smearing, regardless of the period of your input waveform. It also makes clear that the special case of a periodic signal that matches the FFT period happens not because the scalloping effect doesn't happen in that case, but only because its zeros happen to line up with the bin frequencies.
E On Mon, Dec 8, 2014 at 3:28 PM, Jerry <lancebo...@qwest.net> wrote: > > On Dec 8, 2014, at 2:33 PM, Ethan Duni <ethan.d...@gmail.com> wrote: > > >> what other presumption is there? i, personally, have never seen a > > sequence of > >> samples of audio or music that was not "equidistant and linearly > > sampled". it's > >> what we call "uniform sampling". > > > > Some of this new stuff in compressive sensing/sparse reconstruction > > involves non-uniform sampling. Not that I've seen it used much in > practice > > in audio and music, and anyway it would typically be done on top of > > conventional sampling anyway in those contexts (and largely invisible to > > the audio/music side of things, at least if done right). > > > >> dunno what you're getting at, Theo. both graphics appear fully as > > expected to me. > > > > Yeah I'm at a loss as well. Isn't this stuff well-explained on Wikipedia, > > and in every book that covers spectral analysis? > > > > E > > > I think the OP is a bit of a beginner and that the usual generous response > of this list would be helpful. Others' comments on leakage -> windowing and > aliasing are obviously correct but maybe not tuned to the level of the OP. > > Jerry > > -- > dupswapdrop -- the music-dsp mailing list and website: > subscription info, FAQ, source code archive, list archive, book reviews, > dsp links > http://music.columbia.edu/cmc/music-dsp > http://music.columbia.edu/mailman/listinfo/music-dsp > -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
