Hi Dave,

  I had more success than I expected in making a waterfall display of
your file. I have prepared a ZIP file containing the WAV format
version, and the resulting waterfall display of the spectrum. The WAV
file sampling rate is 4.0 Khz, representing a speed-up of 78.48616
times, so the frequency scale of the waterfall plot should be divided
by this number to get the actual frequency. The time scale is
compressed by the same factor.

  http://bobmcclure90.googlepages.com/Helicopter.zip

---Bob


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Subject: Re: waterfall plot of infrasound data files?
From: Robert McClure bobmcclure90@.........
Date: Thu, 18 Jun 2009 22:52:26 -0400

On Thu, Jun 18, 2009 at 3:37 PM, David Saum wrote:
Can anyone suggest software to plot this data to display the dopper
shift?  Perhaps a stacked 3D spectra-time plot, or a 2D waterfall of
frequency vs time?  Of
course I can generate any of the Amaseis file formats or any of the
WinQuake formats as program inputs.


Hi Dave,

  For waterfall displays of WAV files, I use the free Raven Lite program:

  http://www.birds.cornell.edu/brp/raven/RavenOverview.html

  I have my own programs for converting SAC and WinQuake files to WAV
format. See

  http://bobmcclure90.googlepages.com/winsac

  I will try to see if I can do anything with your file, but it is so
short the waterfall will not show much. Faster sampling would help.
Waterfall displays are helpful for analyzing music and bird songs, but
for not much good for earthquakes, for example.

---Bob
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Subj:    Re: waterfall plot of infrasound data files
Date:    06/18/2009
To:    dsaum@............

Hi Dave,

  I will tell you how to see a "movie" of the Doppler shift in your file:

1. Load your SAC file into WinQuake.
2. Set the X-Scale to 6 seconds.
3. Select "FFT, View Only" in the "Calculate" menu.
4. In the "Window" menu, select "Arrange".
5. Click on and hold down the right arrow of the horizontal scroll bar
at the bottom of the window. You will see a succession of FFT's as the
data scrolls by. You will see a spectral peak that shifts.

Cheers,

Bob
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