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Re: AO-51 SSB/FM mode



Quoting George Henry <ka3hsw@earthlink.net>:

> ----- Original Message ----- 
> From: "Bruce Robertson" <broberts@mta.ca>
> To: <amsat-bb@amsat.org>
> Sent: Monday, January 16, 2006 7:07 AM
> Subject: [amsat-bb] AO-51 SSB/FM mode
> 
> 
> > I've just used a pass over the Atlantic to test out the SSB/FM mode
> on
> > AO-51. I can confirm Stephan's observation that this is a relatively
> QRO
> > mode: the same 5w which do just fine on FO-29 and on SO-50 and AO-51
> in FM
> > modes is apparently insufficient here. As a guess, I'd say I need
> about 3
> > more dB because I can hear myself whistling but a speech signal is too
> far
> > into the noise of the FM signal.
> >
> > This raises two questions:
> >
> > A) Does anyone know why this would be the case?
> >
> 
> Because a whistle produces a much higher peak envelope power than speech
> 
> does and, as Drew pointed out, the volume of your downlink in the SSB/FM
> 
> depends, to a point, on the strength of your uplink.
> 

Oh, sorry, the difference between whistling and speech was offered as
evidence for my estimation that 3 dB more power was needed; it's not a
puzzle in itself. The antecedent to my question was the entire previous
paragraph: I observed, as did Stephan, that in SSB mode AO-51 hears less
well than it does in FM mode. 

As I understood Drew's comments, he was also offering evidence to the
contrary, namely that 2w of SSB up sufficed for him in previous instances
of this mode. In any case, this mode is great fun and fine experimentation.
 I take it this is the SQRX multiband receiver in operation (Gould Smith,
p. 61), as opposed to one of RX1-3? That may be a sufficient reason.

73, Bruce
VE9QRP
----
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