[amsat-bb] Re: PC clock

[i8cvs]

Hi Herich, DK1TB

When manually tracking a LEO satellite beginning from OSCAR-6 I
realized the same trick to point the antennas with an angle  5 to 10
degree in front of the satellite position.

The same technique is used by hunters to shoot down birds.

73" de

i8CVS Domenico

----- Original Message -----
From: "Erich Eichmann" <erich.eichmann at t-online.de>
To: "Mark L. Hammond" <marklhammond at gmail.com>
Cc: <amsat-bb at amsat.org>
Sent: Wednesday, May 12, 2010 10:50 AM
Subject: [amsat-bb] Re: PC clock


> Hello Mark, Domenico  and others,
> when SatPC32 updates the antenna positions it turns the antennas a half
step
> in front of the satellites position. The manual says:
>
> "Under all tracking options, the rotors are activated with a precession of
> one half step, either one half of the time interval or one half of the
> tracking angle, to ensure that the satellite moves through the antenna
> focus."
>
> 73s, Erich, DK1TB
>
> ----- Original Message -----
> From: "Mark L. Hammond" <marklhammond at gmail.com>
> To: "i8cvs" <domenico.i8cvs at tin.it>
> Cc: "AMSAT-BB" <amsat-bb at amsat.org>; <W7IN at montana.com>
> Sent: Tuesday, May 11, 2010 10:25 PM
> Subject: [amsat-bb] Re: PC clock
>
>
> Hello Domenico,
>
> The very excellent SatPC32 program "leads" so as to keep an accurate
> pointing at a satellite.  It has several adjustments for how often the
> rotors are updated, gain consideration of the antennas in use, etc.
>
> 73,
>
> Mark N8MH
>
> On Tue, May 11, 2010 at 4:07 PM, i8cvs <domenico.i8cvs at tin.it> wrote:
> > ----- Original Message -----
> > From: "Greg D." <ko6th_greg at hotmail.com>
> > To: <w7in at montana.com>
> > Cc: <amsat-bb at amsat.org>
> > Sent: Tuesday, May 11, 2010 7:47 AM
> > Subject: [amsat-bb] Re: PC clock
> >>
> >> Hi Larry,
> >>
> >> Ok, I understand the need for an accurate clock, though I believe
you're
> >> expectations for being able to track an overhead pass is pushing the
> >> limits of orbital prediction pretty hard. Another ham I know locally
> >> tried this, and ultimately gave up. His issue was not one of clock
> >> accuracy, but of Keps and the mathematics behind them.
> >>
> >>
> >> Greg KO6TH
> >>
> > Hi Greg, KO6TH
> >
> > When the software calculate the Az and the El of the satellite at the
> > right
> > time with an accurate clock then it send a command to the rotators but
the
> > antennas takes a certain time to go in that calculated position and when
> > the
> > antennas are finally there then the satellite is already in another
> > position
> > far advanced in it's orbital path particularly when the satellite pass
is
> > overhead.
> >
> > I dont think you want to run the motors every 5 or 10 seconds othervise
> > your
> > control relays will work as a machine-gun
> >
> > So the issue is not on clock accuracy or Keps or mathematics behind them
> > but
> > it is on the tracking system that we normally use to mimichaise the
> > satellite position with a phase difference between the satellite
> > calculated
> > position and the actual antenna position when the traching command is
sent
> > to the motors.
> >
> > If you go over the roof and you follow the ISS by naked eye you will
> > realize
> > that your antenna pointing is always a little bit behind the ISS
position
> > in
> > the sky and so a very accurate clock to track a LEO satellite is meaning
> > less particularly using high gain antennas with a narrow main lobe.
> >
> > 73" de
> >
> > i8CVS Domenico
> >
> >
> >
> > _______________________________________________
> > Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT-NA member? Join now to support the amateur satellite
program!
> > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
> >
>
>
>
> --
> Mark L. Hammond [N8MH]
>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!

> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb