[amsat-bb] Re: Dual Hop

Robert Bruninga bruninga at usna.edu
Fri Mar 30 05:07:00 PST 2007

> The ANDE & RAFT satellites maybe be a little 
> difficult with simple omnidirectional antennas, 
> but both are a breeze with just a little more antenna.

Sil,  Thanks for the report.
Do not worry about ANDE usage.  It is well below anticipated, so
we are not woried about life.  But this week both are entering
night time prime-time in the northern hemisphere and so usage
will increase.

Also, I do want your assessment of their links.  My rig is 22
elements cross polarized on AZ/EL mount with 100W amp/preamp at
base fed from 150' of coax.  I have not changed it in years,
since I get the same performance to a VHF DX beacon about 30
miles away...

BUT... 1) The preamp is not really a low noise one, just one of
those in a 100W remote PA to overcome some coax loss.  2) I
suspect my deviation setting could be tweaked...

My results are:
1) I cannot access RAFT below 20 degrees and never in the day
(due to overvoltage)
2) I can decode RAFT above about 10 deg, and some times all the
way to 1 deg if lucky 
3) ANDE is also about 10 deg but sometimes lower.

If you get better performance, let me know, since I want to know
how my performance is relative to other setups..  I measure
performance relative to elevation angle, because that is a
direct correlation to range.


> -----Original Message-----
> From: Sil - ZL2CIA [mailto:zl2cia at amsat.org] 
> Sent: Friday, March 30, 2007 12:16 AM
> To: bruninga at usna.edu; AMSAT
> Subject: Re: [amsat-bb] Dual Hop
> > 
> > 
> > Actually, they are intentinoally on the same frequency and
> > are intended to be dual or even triple hop possible (when
> > PCSAT-1 is working)..  Notice that both satelites respond to
> > same path VIA ARISS.  SO you could use the path VIA
> > and get a dual hop.  This ia also why we invite any other
> > university or amateur satellite builder to add more
> > on this 1200 baud relay channel (with IARU coordination of
> > course).
> > 
> Bob,
> Thanks for your reply.
> I have already tried "via APRSAT,APRSAT,SGATE a 
> number of times, but so far without successs. I 
> wasn't sure if this was an acceptable practice, so 
> I had been discrete about it.
> I have been previously successful once getting a 
> dual hop between PCSAT-1 and the ISS (when it was 
> operating on 145.825 MHz)
> The ANDE & RAFT satellites maybe be a little 
> difficult with simple omnidirectional antennas, 
> but both are a breeze with just a little more antenna.
> I use nothing more than a horizontally polarised 6 
> element beam. It's home built and that without any 
> fancy tools. It's horizontally mounted and 
> steerable in azimuth with a simple rotator. I 
> mention this just to make the point that both are 
> really pretty easy satellites to work with just a 
> little more antenna.
> Both satellites are very quiet down here and I 
> very seldom see any other users. I end up gating 
> my own packets. This does allow me to experiment 
> since I'm not obstructing anyone else.
> I'll persevere with further dual hop tests in the 
> future now that I understand it's okay to do so.
> I am of course aware of ANDE-1's rather finite 
> power reserve and do keep that in mind.
> Sil

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