[TenTec] Pegasus/Jupe Band Scope Questn

[Duane - N9DG]

I suppose you can use the 2.5 kHz steps as a design point.
Have the external sound card program take 2.5 kHZ wide "snap
shots" of the 12 KHz IF signal at each 2.5 kHz step. Then
just tune the first LO for as many 2.5 kHz chunks you want
(within reason) and then have the sound card program stack
those 2.5 kHz pieces of spectrum back together along the X
axis of the sweep window.

Once we've made the leap to using the 12 kHz IF tap then the
DSP AGC behavior of the Pegasus/Jupiter is moot. All we need
to be concerned with then is tuning the 1st LO in 2.5 kHz
steps and coordinating that with the external software.

Duane
N9DG


--- Carl Moreschi <n4py at earthlink.net> wrote:

> The 12 khz IF only moves in 2.5 khz steps.  There would be
> no way to be more
> accurate in the sweep display than 2.5 khz.  You would end
> up with a plot of
> vertical blocks, each 2.5 khz wide.
> 
> Having the jupiter firmware provide real antenna voltage
> not affected by AGC
> seems the best way to go to me.
> 
> Carl Moreschi N4PY
> Franklinton, North Carolina
> n4py at earthlink.net
> ----- Original Message -----
> From: "Mark Erbaugh" <mark at microenh.com>
> To: "Discussion of Ten-Tec Equipment"
> <tentec at contesting.com>
> Sent: Wednesday, February 23, 2005 10:59 AM
> Subject: Re: [TenTec] Pegasus/Jupe Band Scope Questn
> 
> 
> > > It makes sense. When the Jupiter does it's own scan,
> it's much
> > > faster. 2 questions:
> > >
> > > Does the agc not affect the Jupe in standalone mode
> scanning?
> > >
> > > Could a firmware change take care of this?
> >
> > I asked Gary Barbour at TenTec the same questions a while
> back.
> >
> > In sweep mode, the Jupiter firmware does bypass the AGC
> and it would be
> > possible to add that mode (AGC off) as a setting for use
> with external
> > sweeps.
> >
> > However, I'm considering another alternative. There is a
> mod to the
> Pegasus
> > and Jupiter that brings the 12 kHz IF out to the spare
> jack on the back of
> > the radio. This IF is normally fed to a computer
> soundcard where it is
> used
> > to decode DRM (digital shortware broadcast) signals. This
> IF is unaffected
> > by the digital AGC in the radio (as it is still in the
> analog stages of
> the
> > radio). This signal could be analyzed in the a computer
> program to provide
> a
> > sweep.  There would have to be some coordination between
> the analog tuning
> > and the signal received, but it should be possible to get
> a nice sweep
> > display.  In fact, it should be possible to provide a
> real time band sweep
> > of signals adjacent to the current signal, at least those
> within the width
> > of the 20 kHz roofing filter.
> >
> > 73,
> > Mark
> >
> > _______________________________________________
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> > TenTec at contesting.com
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> 
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