Fwd: [PVRC] OTH Radar
Pete Smith N4ZR
Thought this would be on interest to Ham SCI. I think I found the PLUTO site on Cyprus.
73, Pete N4ZR
-------- Forwarded Message --------
| Subject: | Re: [PVRC] OTH Radar |
|---|---|
| Date: | Wed, 2 Dec 2020 08:57:53 -0500 |
| From: | W3KL <w3kl.amateur....@gmail.com> |
| To: | 'Alfred Laun' <hs0...@gmail.com> |
| CC: | 'PVRC' <pv...@mailman.qth.net> |
Hi Fred.
PLUTO (not to be confused with the Italian S-band search radar that goes by the same name) is an HF FMCW radar. The waveform is a simple FMCW that can give distance and speed of a moving target located beyond the horizon. Of course, with any OTH HF radar the effects of the ionosphere have to be taken into consideration and can cause lots of errors. In addition the usual problems of radar clutter suppression have to be dealt with. Much has been done by the US DoD and IC in the area of modeling the ionoshphere in real time to deconvolve propagation effects in order to improve the accuracy and precision of OTH radar and HF geolocation (find an HF transmitter 2000 miles away with high accuracy and precision). FOGHORN is a chirped pulse radar (don’t hold me to that – I do have a open lit paper on it somewhere).
As I said, the DOD and IC have invested a LOT into real time propagation modeling in order to provide more accuracy and precision. What remains is to explore different aperture formats and to utilize at more advanced waveforms. If you look in the open source literature on DTIC you’ll find unclassified papers on some of the recent work on all of this – mostly by university groups doing proof of principle work. Anything with operational data or results is not in the open literature unfortunately, this includes a lot of the results of real-time modeling. Anything in the DOD and IC having to do with any kind of advanced waveform R&D or algorithms for same are highly classified.
In addition, any work on the specific threat that is being searched for (either actively or passively) is also highly classified. DARPA’s SHOSTY project is focused on not only waveforms and algorithms but also aperture format. It’s now being transitioned to a downstream customer in the DOD. As an aside, the DOD ALWAYS coordinates with the FCC when the use spectrum that isn’t allocated for the specific use. I’m not sure to the extent that the FCC would coordinate with primary users – certainly if the use interfered with critical coms (aircraft or radio nav for example) they would – but in a ham band? Hmmmm….I’m not sure. That being said I’m not saying that SHOSTY ever did or will use a ham band, but as I said below, this isn’t going away anytime soon. Now that it’s possible to model the ionosphere accurately enough in real time (via something like a finite difference, time domain (FDTD) method) HF OTH radar is going to become a very attractive way of finding near peer adversary threats at standoff distances of several thousand miles without having to rely on satellite ISR as satellites are only useful if the target happens to be in range when the event occurs. Even a constellation of LEO ISR birds will have gaps in coverage that the adversary can exploit (yes, you can find a single 6U cubesat bus at 300 km altitude from the earth’s surface).
As an aside, one of my clients has had a program in the IARPA HFGeo program. To cut to the chase, I often realized that hams would love to have the capability that is being developed in HFGeo since we could then locate with very small error the location of any DX cop or intentional jamming. How small is not public unfortunately. However, I will say (and this you can find in the open literature) that HFGeo didn’t use an antenna in the sense that hams understand an antenna to be. Instead it uses a (relatively small – you can find pictures of some of the on the internet) six axis HF EM vector sensor. For the physicists out there it finds the Poynting vector (which is why you need three E field components and three H field components) of the incoming RF. Take the vector inverse of the Poynting vector and you know the direction from whence the EM radiation came – and that’s where the real time propagation modeling comes in. It then becomes a massive inverse problem – which is tractable today in near real time without a supercomputer.
73, Jeff
W3KL
From: Alfred Laun
<hs0...@gmail.com>
Sent: Wednesday, December 2, 2020 1:06 AM
To: W3KL <w3kl.amateur....@gmail.com>
Cc: PVRC <pv...@mailman.qth.net>
Subject: Re: [PVRC] OTH Radar
According to the latest IARU Region 1 IARUMS Newsletter at:
EA6AMM identifies OTH Radar signals on 21130 21140 21145 21210 and 21290 between October 7 and October 30 as originating from "PLUTO"
The "PLUTO" signal originates from British bases in Cyprus according to this web site:
In the same report, EA6AMM identifies OTH radar signals observed during the same date periods on 21218 21324 and 21381 as "Foghorn"
"Foghorn" originates in China according to:
73, Fred, K3ZO
On Tue, Dec 1, 2020 at 8:09 PM W3KL <w3kl.amateur....@gmail.com> wrote:
There was a comment on the contesting reflector about QRM around 21.050 MHz during the contest this weekend.
Frank, W3LPL, correctly identified the source as over the horizon (OTH) radar. In the past the Russians and Chinese were the go to sources of OTH radar QRM.
However, we can expect the problem to persist and maybe get worse. There are a few US DoD and intelligence community programs looking at OTH radar. DARPA (the Defense Advanced Research Projects Agency) is running a program called SHOSTY that is exploring HF OTH radar with a focus on different waveforms (modulation techniques). One of my clients has a contract in Shosty and a similar project run by IARPA (Intelligence Advanced Research Projects Agency).
You can find some limited information about these programs on the internet. The military application and also the frequencies and the nature of the waveforms are not public however (full disclosure: I’m not implying that the 15 M QRM came from Shosty). One might be able to glean something about what they are doing by digitizing the receive signal, but it would be very difficult to really understand what’s happening because of the way the transmit aperture works.
73, Jeff
W3KL.
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