archiv~1.txt: SETI Re: Argus: Accurately positioning dish

SETI Re: Argus: Accurately positioning dish

MarcusJohn@aol.com
Sun, 14 Mar 1999 13:59:33 EST

In a message dated 3/14/99 9:17:01 AM Eastern Standard Time,
badam@willinet.net writes:

>
> Adrian and Malcolm,
>
> The problem of knowing where the dish is pointed has bothered me also.
> I've mentioned this before, but I think that I've an idea for at least a
> partial solution. First, think of GPS satellites as signal generators with
> VERY accurately known positions and "relative" signal strengths determined
> with reference dipoles or quadrifillers. Next, let the signal generators
> sweep (many times, many paths) through the antenna pattern while recording
> signal strength through both the dish and reference antennas. Last,
> determine a "best fit" pattern to characterize the dish and where it's
> pointed.
> This is a simplification of a complex problem and several assumptions are
> needed. Once you move the system's frequency from the 1575.42 MHz GPS
band,
> the pattern will change. But, is this a predictable transformation once
you
> have an experimental solution at one frequency? My gut tells me that the
> pattern will be very different but the central point of the pattern will
> remain constant, except maybe in "spurious" configurations.
> This, I admit, is an "off the wall", "pie in the sky" idea for which I
> don't have time right now ... but it has intrigued me.
>
> Brian
> Argus Observatory EN12sn
>

Brian, this is a tour de force of creativity. Another prize for Brian!.

This is exactly the kind of creativity and solution that makes privatised
science cheaper and better than publicly funded brute force answers.

Think about this. If this answer works, then we have a potentially software
only solution to the pointing question. All that we need is to hold the dish
still. In a couple of sweeps of the GPS sats, we have the pointing parameters.
We don't even need to decode the GPS signals, if we have accurate Keplers. No
need for expensive levels, protractors, hours of measurement, all kinds of
errors in physical measurement.

For 5 thousand Argus stations, think of the man and women hours of work
that can be saved. And the precision would be tremendous.

Of course, someone needs to do the nitty gritty programming. Sounds like a
good sized job.

Anybody care to write an algorithm in English, just to get started?

John Marcus
KE3SW.