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Re: Crossband repeat on ISS



Hi Gregg,

I totally agree with Drew on this and I like his conclusion very 
much.  I wish there was a magic solution for new satellite users to 
experience the ISS, but the only solution I know of is practice and 
experimentation (and maybe some luck).

I don't own a D700 (ISS Equipment) but I would speculate that the key 
is to have a signal in the middle of the FM capture range the radio 
is tuned to.  Keep in mind that the receiver on the ISS is tuned to a 
single frequency and never moves, but that unless you are using full 
Doppler tuning you are not on frequency.

I believe I can get in on 5 watts because I'm using full Doppler 
tuning (I don't have a mega antenna - just a small beam with no 
rotator). I believe if your transmissions are not reaching the ISS at 
the exact center of it's frequency, you will have a more difficult 
chance of your FM signal being captured because it is deviating 
beyond that range.

A good experiment would be to find a friend and ask him to tune his 
handheld to 446.000 MHz and drive 20 miles away while still line of 
sight.  You then transmit on 446.005 MHz (off frequency) in low power 
(1W). Ask him how your signal quality sounds. It's probably not good 
if at all.  That is pretty close to what it is like working the ISS 
if you don't use Doppler tuning.

I recall that AO-51 was engineered with a capture range wider than a 
standard FM receiver for this purpose.  Perhaps someone who worked on 
that project can add some thoughts.

73 and happy New Year,

Emily



At 03:34 PM 12/31/2005, Andrew Glasbrenner wrote:
>It's got very little to do with the "big guns" and more to do with 
>the dozens of stations trying, many half duplex, who just don't have 
>satellite operation down yet. The half duplex crowd can't hear if 
>they are making it or not, so gum up the works all the worse. I've 
>found the usefulness of an FM sat is inversely proportional to the 
>power level of the downlink due to this effect. Give me SO-50 over ISS any day.
>
>Don't hate the players, hate the game.
>
>73, Drew KO4MA
>
>-----Original Message-----
> >From: Gregg Wonderly <w5ggw@cox.net>
> >Sent: Dec 31, 2005 6:18 PM
> >To: John Geiger <ne0p@lcisp.com>
> >Cc: AMSAT-BB <amsat-bb@amsat.org>
> >Subject: Re: [amsat-bb] Crossband repeat on ISS
> >
> >John Geiger wrote:
> >> I have been trying to get on the ISS crossband repeater with no 
> luck today.
> >> Using 437.800, no PL as stated on the AMSAT website for the 
> uplink.  What am I
> >> doing wrong?  Getting a great downlink signal from it.
> >
> >You're not running 100watts into a 23dbi antenna system on a rotator.
> >
> >The big guns are killing the usefulness of this great resource...
> >
> >Gregg Wonderly
> >W5GGW
> >----
> >Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> >Not an AMSAT member? Join now to support the amateur satellite program!
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>----
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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