Rune Allnor wrote:> Richard Owlett <rowlett@atlascomm.net> wrote in message news:<10hibo6o2lr1h1d@corp.supernews.com>... > > >>What I'm considering is: >> 1. do a series of FFT's on constant with windows with a constant >>time offset. >> 2. on each FFT, sum the squares of (fft)bin values over appropriate >>range of bins >> 3. create some sort of 3D surface plot of result >> >>Is there a computationally &/or ????? simpler approach? > > > There might just be. > > I'd suggest an approach based on filter banks, that might do what you > want. My approach does, however, rely on a couple of relatively tricky > aspects of DSP (IIR filters and Envelope Detectors) that may be > cumbersome to design when one is not euded to working with these kinds > of things. Once the system is up and running, it may be easier from > a usere's perspective, and might also provide results that may or may > not be somewhat easier to interpret. > > --- CAVEAT --- > > The time-domain data generated below might not be useful for your > speech processing application. You might nevrtheless find the > excercise interesting. > > --- oo00oo --- > > I'm using matlab synatx when appropriate, which shouldn't be too > dissimilar from scilab. >Your reference to Envelope Detectors pointed me to solution of an unrelated problem I'd been thinking about. I'll have to try the filter bank approach. If it isn't in some way better I will get a different perspective on my topic and learn more DSP ( wonder if Rick will mow my lawn while i read his book ;) [ snip Outline of algorithm: and Matlab Pseudo Code ]> > I've got the impression from other posts of yours that you don't > like surface/contour plots too much. Perhaps you find the waterfall > display more convenient. >It not that I don't like them, I just couldn't seem to get either scilab or gnuplot work well. The only useful feedback I got from respective support newsgroups was that I was trying to plot too much data. I resorted to waterfall display, not knowing it had a name. Its only problem is point of view can not be changed.
Characterizing speech -- revisited [ long winded with question at end ]
Started by ●August 10, 2004
Reply by ●August 12, 20042004-08-12
Reply by ●August 12, 20042004-08-12
"Richard Owlett" <rowlett@atlascomm.net> wrote in message news:10hmlvh4m4u8ae7@corp.supernews.com...> Jerry Avins wrote: > > Richard Owlett wrote: > > > > ... > > > >> The question of this thread should be rephrased. > >> Can a batch of z filter banks be more computationally/programatically > >> more efficient than doing an FFT and appropriately summing the z > >> intervals. > > > > > > What is a Z interval? > > > > Jerry > > z is just a number > I would just "chop" fft bins into z groups such that > grouping bins > 1 n(1)--n(2) > 2 n(3)--n(4) > | | > z n(m)--n(m+1)Computation efficiency would depend on what 'z' is and the actual implementation, so that's an "it depends". But in terms of programatic efficiency, staying in the time domain and using filter banks should use much less code than an FFT approach.
Reply by ●August 12, 20042004-08-12
Richard Owlett wrote:> Rune Allnor wrote: > >[snip] > >> >> I've got the impression from other posts of yours that you don't like >> surface/contour plots too much. Perhaps you find the waterfall display >> more convenient. >> > > It not that I don't like them, I just couldn't seem to get either scilab > or gnuplot work well. The only useful feedback I got from respective > support newsgroups was that I was trying to plot too much data. I > resorted to waterfall display, not knowing it had a name. Its only > problem is point of view can not be changed.Can someone point me to a description of what is meant by "waterfall display"? I had done a Google search and came up with manufacturers' pages describing instruments/programs with waterfall displays as an output. Their graphics and Rick's pseudo code looked similar to what i dad been doing. OK they are similar, but are they the same? I'm suspicious that I might be missing some underlying assumption.
