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[aprssig] Deviation meters

Stephen H. Smith wa8lmf2 at aol.com
Thu Apr 5 16:29:57 UTC 2007

johnk.mchugh at att.net wrote:
> The Bezzel function for the first carrier null is 2.405. The formula 
> is (Required Dev/ 2.405). So if you want to set the deviation to 
> 3.5KHz, use an audio tone of  3.5/2.405 or  1.455KHz. Oh, you don't 
> have a 1.455KHz tone, then use the mark tone from a KAM, usually 
> 1600Hz on HF. There must be software that will produce variable audio 
> tones from a sound card, anyone know of such a program?
> John

The freeware utility bundle  "Wavetools" on my web site downloads page 
will do this.

It bundles 4 applications that use the sound card: an audio function 
generator, an audio level (a.k.a. "V.U.) meter, a dual trace scope and 
an audio spectrum analyzer. 

Go to < http://wa8lmf.com/miscinfo > and look for the file 
"Wavetools.exe" near the bottom of the list.

By the way, it's Bessel , not Bezzel .    Incidentally, the traditional 
RTTY mark tone of 2125 Hz produces a Bessel null at 5.1 KHz deviation.     


Stephen H. Smith    wa8lmf (at) aol.com
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