| Need help with Wavelet Workbench [message #14836] |
Wed, 07 April 1999 00:00  |
jkbishop
Messages: 1
Registered: April 1999
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Junior Member |
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I'm trying to use Wavelet Workbench on a long (48000 pt) signal. I
think that two separate problems are occuring.
I upsampled the data set to 65536 points (by zero padding in frequency
space). I hacked wreaddat, wdyadlng, wdyad, and wfwtpo to use long
integers in some places. The result is that I can now plot the
scalogram for my data set (wreaddat, wintwave, wdoscog are the
programs I'm calling). However, the plot of the scalogram looks like
only the first half of the data set is being used. The coarser scales
have some variation just beyond the half-way point (bleed-over from
the convolution process?), but the more detailed scales show a solid
color in the upper half of the time axis. Anyone have any ideas what
is going on?
So far, I have tried upsampling again to 2*65536 points (whatever
that is). The result is that the convolution-by-FFT process in
wmfilt takes forever (I didn't wait for it to finish; it was taking at
least 10 times as long as the 65536 point set, as verified by
printed status statements). I don't understand why, but would
the FFT process be the problem with the 65536 data set?
To get an answer, my next approach was to downsample to
32768 points. This brings me to the second problem, which is a
type conversion problem in wintwave. For the 65536 point data
set, this part seems to work fine (with the adjustment of 2 to 2L in
the line that finds n_work). When I put the 32768 point set in,
the data set gets truncated to 16384 points because
fix(alog(n_elements(x_work))/alog(2))) evaluates to 14 instead of
15. alog(n_elements(x_work))/alog(2)) is given as 15.0000. Can
someone explain this so even a mechanical engineer can
understand? To get around this one, I have just inhibited the
length check; I just have to be careful to only use dyadic length
sets.
Any help would be appreciated.
--
Jonathan Bishop
jkbishop at frontiernet dot net
jab7981 at rit dot edu
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