[amsat-bb] Re: thought for a neat product, anyone seen one?
n3tl at bellsouth.net
Sun Nov 23 20:43:43 PST 2008
As far as pointing your antenna in full-manual operation - and until you or someone gets that neat little box built, tested and rnuning - let me offer a couple of ideas.
First and most importantly, start watching visible passes of the International Space Station. Note the azimuth positions for acquisition, maximum elevation and loss of visual. The tracking software I use tells me where the ISS will rise and set at the horizon, but my personal experience is that it often doesn't come into view here until it reaches 10-or-so degrees of elevation. That's important if you try to track from closer to the horizon because the ISS coming into view might be misleading because it's often higher than the horizon before you can see it.
The more passes you watch, the more accustomed you'll become to judging maximum elevation. Before long, you will be able to take the schedules generated by programs like SatPC32 and Orbitron and "visualiize" how a satellite will move across the sky. I use a Brunton Satellite Alignment base plate compass, which I just discovered a few months ago. Sells online for $12. It includes a protractor of sorts on one end of the base plate that will show you elevations up to 60 degrees.
So ... let's say I have a pass of AO-51 coming up with AOS at azimuth 178 degrees; maximum elevation of 55 degrees at azimuth 260 degrees; and LOS at azimuth 341 degrees. I go out a few minutes before the pass and, using the compass, find visible landmarks that correspond with the three azimuth positions. Then, I get an idea of exactly where in the sky it will be at maximum elevation (i.e., i go up 55 degrees from azimuth 260). I'm going to follow it up the sky with my handheld antenna from 178 to 260, then follow it down from 260 to 341. Those "practice" ISS passes help me to visualize that line.
As Patrick mentioned, SatPC32 will automatically track Doppler for you, even with two radios as he (and I) use. I'm still doing everything manually here, but look forward to being able to use computer control if I choose.
I hope ths proves helpful. Best of luck with your satellite work!
Tim - N3TL
AMSAT Member No. 36820
QRP-ARCI Member No. 5547
ARRL Member No. 0007027180
Athens, Ga. - EM84ha
-------------- Original message from "Eric Fort" <eric.fort at gmail.com>: --------------
> I just thought of kind of a neat product for those of us that work sats.
> Has anyone seen anything similar? I have an ft-817 which has a cat
> interface and will operate both ssb and fm. Has anyone seen a little box
> that would adjust the radio frequency for both uplink and downlink while
> displaying azmuth and elevation data? It seems that it would be handy to
> have the frequency control take care of itself while providing data as to
> where I should point the arrow. What do those reading this idea think of
> it? It would seem to me to be quite useful especially for ssb.
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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