[Milsurplus] Strange Sound On Air- Data Burst?

[joldenburg2 at new.rr.com]

Sounds like a chirpsounder:

http://en.wikipedia.org/wiki/Ionosonde


---- "J. Forster" <jfor at quikus.com> wrote: 

=============
There are sounders used to check propagation between sites. They send a
bit, measure S/N, skip to a new frequency, and repeat. Most often used for
things like embassy HF links, I think.

Maybe one of those?

-John

=============



> For years I've occasionally heard this sound on the bands:
>
> http://home.netcom.com/~arc5/pulses.wav
>
> It is not swept; it's specific to a frequency.
> Often, there is only one set of two pulses.
> Sometimes there are three sets, other times several more.
>
> I've been told these are data bursts sent from one RDF site
> to another, which replies.  These bursts are used to adjust
> the site calibration vs. real-time propagation, giving a more
> accurate RDF "fix."   I think this was the person's theory,
> rather than any certain knowledge.
>
> Does anyone have an idea?
>
> 73 DE Dave AB5S
>
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Jon Oldenburg AB9AH
"A bicycle can't stand on it's own because it is two tired..."