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Re: Doppler #2



Brent,

Doppler does affect sub-carriers as well, but in proportion to the actual
frequency about .006 Hz on a 67 Hz tone. I doubt that the decoder is that
sensitive!
A point learned from FM repeaters is that as the signal goes below full
quieting the make up of the recovered audio is a mixture of noise and
signal, with the signal being reduced in content relative to the noise.

Conventional repeater operation requires the encode tone to be set at 1 KHz
of deviation and the decoder set to decode at a level of 150 Hz of
deviation. Anything less than 150 Hz of deviation from the ctcss tone  is
mostly noise and not useful to open the repeater. I don't know where the
threshold is set on Echo, but those having problems might want to try
boosting the deviation level of their encode pl. I would suggest that those
trying this have some means to monitor the level and be able to reset it to
it's original value.

Art, KC6UQH

----- Original Message -----
From: "Brent Taylor" <btaylor@nbnet.nb.ca>
To: <amsat-bb@AMSAT.Org>
Sent: Friday, July 30, 2004 5:01 AM
Subject: [amsat-bb] Doppler #2


> After sending out my first question, it dawned on me that, of course, with
> FM and with the speed of light, there is no way Doppler could affect the
> frequency of the received tone.
>
> (heading for  a cold shower).
>
> Brent, VE1JH
> FN66
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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