funkbastler wrote:
On 4 May 2005 18:26:59 -0700, "Herbert Blenner"
wrote:


I have a wave file from a radio reception made four decades ago.

ftp://www.members.aol.com/hdblenner/sound.wav

The sound is familiar to me and wonder how others would characterize
this signal?

I withhold my opinion of the sound to avoid biasing the views of
others.


First, I'm going to assume that there's a problem with the way the
file is encoded - if it's stretched out to 10 seconds (more or less)
then you can start getting a sense of what's going on.

A problem with file encoding would not surprised me. I wrote the code
to generate this wave file from a 21 megabyte file. Speech comes out
fine so if errors are present they are minor.


Sounds like some sort of analog, time-multiplexed, instrumentation
signal to me.

I have also observed evidence of time multiplexing. Short term analysis
shows rapid shifts in spectra. By increasing duration of my transform
to hundreds of milliseconds or longer, I find a dominant sinusoid
emerging around 900 Hz.

I interpret these results as showing a simultaneous amplitude and
frequency modulation of audio.


Herbert



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