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Re: Radar Pings off ISS



Bob,

This past weekend I was listening to the ISS using the Navspasur fence. I
copied the ISS on my first attempt using a single square loop cut for 217MHz
into my R8500 receiver. The IF output of the R8500 radio goes into an SDR-14
receiver. I calculated that the ISS was going to be due east (90º) at lake
Kickapoo, TX at 22:26:17. I copied the reflection 3 seconds early. I have
some observations taken by WA4NJP that show that the fence might actually be
tilted a couple of degrees in elevation toward the south. I am able to hear
reflections from the moon at all 3 frequencies and even at the same time. I
just got a beam antenna and hope to increase the sensitivity. I will be
taking some very high resolution FFT captures (sub Hz) in the next couple of
days using ISS. I hope to capture more detail. You can download a picture of
my first attempt at copying ISS here:

http://www.rfspace.com/ISS.gif

73's

Pieter Ibelings
N4IP
----- Original Message -----
From: "Bob Bruninga" <bruninga@usna.edu>
To: <amsat-bb@AMSAT.Org>
Sent: Tuesday, December 02, 2003 7:15 PM
Subject: [amsat-bb] 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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