Lol well that would be a really big picture. If you could separate the
noise from the signal perhaps. I cant say it's impossible but highly
improbable. Interferometry is only as good as your ability to resolve.
The problem is the sensitivity of the receiver and the ability to filter
out the unwanted noise. If you could do that then you would not need an
array just a better receiver.
It's the same with light if you look at Jupiter with a small telescope
all you see is a disk. The more light you gather the more details are
reviled.
If Jupiter wasn't so bright it would be very difficult to find it in the
sky would it not? With all the other stars in the sky.
With radio we are stuck with the current state of the art. Same as
telescopes.
When you look up in the night sky it's very much like the radio dial
some signals are stronger some are weaker some you cant see. But we know
they are there right :)
So what your trying to do is see a star that is just out of view. If you
pick up a telescope it's much easier.
Sorry, I know that's elementary and you already know that. I can make it
easy for you simple answer No.
But I really really like your style! You forced me to think because I
could not give you an answer with complete confidence it could never be
done.
Heterodyne is a form of interferometry we use in radio to receive and
filter signals. The kind of iterferometry (and no I don't have the time
or inclnation to spell it correctly becazuse you know what I mean) used
between radio telescopes in an array is already focused on a specific
area in the sky. That's why it works a little better than just a bunch
of omnis looking all over the place :) If the array was not pointed then
all you would get is noise and that's pretty much all you would get with
an array of omnis.
Could you process all that noise and find the signal with interferometry
perhaps with enough processing power and time but for now I have to say
no.
Monroe
-------- Original Message --------
Subject: [AR] Re: SDR Radio's was "infrastructure" (was Re: Amateur
solid rockets for ...)
From: Robert Clark <rgregoryclark@xxxxxxxxx>
Date: Mon, December 18, 2017 10:55 am
To: arocket@xxxxxxxxxxxxx
One more stab at it. Cubesats transmission power is less than 1 watt,
while the NOAA weather satellites transmit at less than 10 watts. So if an
omni can receive a NOAA satellite, can we use 10 of the omnis combined
interferometrically as radio telescope arrays do to get the sensitivity
needed for the cubesats?
Bob Clark
On Sat, Dec 16, 2017 at 2:06 PM, Marcus D. Leech <mleech@xxxxxxxxxx> wrote:
On 12/16/2017 01:36 PM, Robert Clark wrote:
On Mon, Nov 20, 2017 at 7:53 PM, Monroe L. King Jr. <
monroe@xxxxxxxxxxxxxxxxxx> wrote:
Cubesats are typical 1 wattCould a omnidirectional antenna like these work to receive cubesat
Besides that the point is you need a tracker.
My mother has a "general" ham license. lol seriously
No a stationary helical would be no good for a cubesat but almost any
other satellite would be doable.
Monroe
transmissions without tracking, to be able to receive transmissions of any
cubesat overflying the coverage area:
The Lindenblad: The Ultimate Satellite Omni Antenna
by Howard Sodja, W6SHP
w6shp@xxxxxxxxx
based on articles previously published in The AMSAT Journal July 1990 and
November-December 1991 and OSCAR News August 1989 and June 1991.
http://www.amsat.org/articles/w6shp/lindy.html
or:
https://en.wikipedia.org/wiki/Omnidirectional_antenna#/
media/File:Schwarzbeck_RE_1790.jpg
Bob Clark
Omnis have been used for VHF satellites, such as the NOAA POES APT
service. But the transmitters on those sats are fairly loud, compared to
the 1W
cubesat example.
Assuming 5dBi gain antennae on both satellite and ground, then at 150MHz,
the free-space path loss is about 112dB. Our putative cubesat puts out
+30dBm,
so the receiver "sees" -82dBm. Whether that's sufficient to service the
SNR needs of whatever signal you're trying to demodulate is another
question.
Moving up in frequency means the path-loss gets worse, but gain antenna
structures are smaller.
