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Radar Pings off ISS



Navy Satellite Radar at 217 MHz:

The Navy operates (for the last 30+ years) a 400 Megawatt(?) ERP radar
transmitter at 217 MHz that pings off every satellite that flies over the
southern USA.  Its called the Navy Space Surivellance Radar (NAVSPASUR).

When any object flies through the 0.5 degree wide FAN beam, you should
hear a quick 1 or 2 second Doppler ping on 216.98 MHz on an SSB receiver
if it is large enough or you have a big enough antenna depending on where
you live.  In Maryland we only get one ISS "ping" opportunity per day
during working hours from the ISS.

On our third attempt we still havent heard anything other than computer
birdies...  but we are only just beginning.  To help, I wrote a program
called SPASUR.EXE that shows you the geometry of where and when to point
your antenna for the ISS and other big objects.

See http://www.ew.usna.edu/~bruninga/raft.html

This site is primarily for our next CUBESAT, but it also has to show the
mids all about the NAVSPASUR radar so they understand the background.  If
you want to see the sample output from SPASUR.EXE or download a copy,
go about 2/3rds of the way down the page...

I know these pings can be heard.  In fact, I have links to WAV files
recorded by Dr. Steven Bienvenu, M.D. of not only satellites, but also
meteors using only a dipole receive antenna in Louisianna. Lots of fun for
anyone interested in listening to things...  10,000 objects a day pass
through the fence.  Though maybe only 100 are big enough for amateurs to
hear..  My calculations show that his nearness to the transmit site gives
him a 15 dB advantage over what we can hear in Maryland.. so we just need
a bit more gain...

Also, the MOON passes through the fence once or twice a day also for more
than a week each month.  Think of it as a 400 MW CW EME transmitter.
Compared to a typical EME HAM transmitter of 1 KW, I still compute that
someone with only a dipole should hear this too?  We are just entering a 2
week phase when the moon goes through the fence...

So, no, I have still not been successful.  Still working on it.  But just
thought someone else might like a new project...

You dont even need any special software.  Just set your OBSERVER
coordinates at the main transmitter site 33.5N and 98.7W and whenever the
ISS passes within a half degree of the fan beam on a bearing of 091 or 271
degrees from that site, then it is in the beam and *if* you can also see
the ISS at that same instant no matter where you are, then you should be
able to receive the reflected energy for about a second...

Or so the theory goes....  still piddling here...

P.S.  There are 100 brightest satellites in the CELESTRAK VISUAL.TXT file,
but that is too much for my program and I am sure some are bigger than
others.  I'd like to filter down the list to the 10 BIGGEST objects and
concentrate on those.  Does anyone know what are the 10 biggest objects
besides the MOON and ISS (and shuttle when it flies)...

de WB4APR@amsat.org, Bob


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