Re: Cepstral analysis made from log-scale FFTs



Michel Rouzic wrote:



Oh yeah, logarithmic frequency, not logarithmic magnitude.
When you think about it, it's just pattern recognition. Surely there
must be a solution to recognising that pattern

Those solutions are more or less empirical and based on features. Such as take the largest peak, then find the largest peaks next to it, check the frequency ratios, check if there are the other peaks with the same relation, repeat until the best result is found.

other than using the
special property of that pattern that if you apply a transform to it
(log scale to linear scale) then you have something with a fixed
periodicity. Like, how would you do it if you had to detect a precise
fixed pattern of peaks but that they had a much more arbitrary and
unremarkable spacing? Normally I know that you can detect any
arbitrary pattern by cross-correlation (seems to work quite well with
images) but in this case cross-correlation doesn't even remotely work,
probably because it's all a bunch of peaks.

Why are you insisting on doing the things in the difficult way?


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
.

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