US Army Developing Encrypted Radar Waveform (thestack.com) 122
An anonymous reader writes: The U.S. army is working on an innovative technology for masking radar emissions in contested territory and environments with heavily congested radio bands. Effective radar system performance is critical in military operations, yet remains a challenge in locations under attack or in areas of high traffic density. Army researchers have now developed a noise-encrypted radar waveform called Advanced Pulse Compression Noise (APCN), which can be tuned in real-time to allow users to adjust radar performance depending on their surroundings. Research scientist, Mark Govoni explained: 'Having the ability to transmit a radar waveform that's continually changing, one that never repeats itself, and looks like noise, is extremely difficult to intercept....and remains anonymous to radar detectors.'
Re:Stay out of high noise areas maybe? (Score:4, Funny)
Re:Stay out of high noise areas maybe? (Score:4, Insightful)
Even the summary says that isn't going to happen.
What "masking radar emissions in contested territory" tells me is that they intend to change their newspeak so that they aren't technically in a war zone but rather in a contested territory. Clearly the Geneva convention doesn't apply to contested territories.
It worked perfectly well for the "illegal combatants". Just invent a new expression and no treaties or laws have direct references to them.
Well, at least they aren't even trying to mask the imperial mindset anymore. I wonder how long it takes before they start taking slaves.
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Did you know that a number of countries have claimed part of Antarctica, in fact I don't think there is any part of the land that isn't claimed by someone. These nations include:
New Zealand
Australia
Great Britain
Norway
Argentina
Chile
France
However the US does not recognize these claims. I think the main US base dpwn there is in the Ross Dependency (NZ territory) but we let them use it since they fly out of Chch
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It worked perfectly well for the "illegal combatants". Just invent a new expression and no treaties or laws have direct references to them.
Sigh. No. Pretty much every treaty about how armies behave has included rules for brigands, pirates, or other "illegal combatants". The rules allow them to be executed at a whim, with the only trial required being a "field tribunal" to confirm they aren't actually members of an actual army.
It's been this way for centuries, in military tradition and then in treaty. Organizing to fight without forming a formal army with a chain of command and ultimate government authority is looked upon quite harshly. Yo
Re:Stay out of high noise areas maybe? (Score:4, Insightful)
I think this is, at best, an ignorant comment. While I think the US is excessive in their military presence around the world, sometimes it's justified and even welcome. Europe is definitely better off for the Americans entering into WWII. While we can debate whether nuclear weapons should have been used against Japan, there was ample reason to fight a war in the Pacific as well. China, an American ally, was under attack by Japan. In the present day, we provide military protection to Japan and South Korea. They are our allies and our presence is welcome. Japan and South Korea face a very real threat from North Korea. I suspect the technique described would have value in Japan and South Korea because of the high traffic density and, in the case of South Korea, hiding the radars from North Korea. Does the US abuse military intervention? Absolutely! But are there countries where the US military presence is welcome? Definitely! And would the technique have value in some of those countries? I'd bet it does. And besides, there's really no way to know where the US military might really be needed in the future.
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I think we have nearly 180 degrees of daylight in between our current policy and isolationaism.
I would describe our current policy as one of corporate profit driven interventionism. How much of our foriegn policy in the middle east for the past half century has been anything other than the United States getting embroiled in the business interests of the Bush family and their cronies? Little Bandar hardly started it, his Daddy had been doing it since his CIA days.
Shit, Iran had a democratic government, who f
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If you are an atheist, you should seriously consider adopting a religion of some sort. Your inability to distinguish between right and wrong, and good and evil, is really quite shocking.
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Do you just hear a "woosh" sound all day long?
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Well, there are spiritualist sects out there that believe nuking kills the souls of those at the flashpoints, while ordinary bloodbaths at least allows said souls to go on. Any way to confirm that? Of course not. But if we ass-u-me it miiiiight be the case, then dropping those bombs was the worst crime in the story of mankind, given all the other wars combined still were at "0 souls killed" territory, and then that changed. ;-)
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That's where all the oil is.
Anonymous? (Score:2)
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Will this avoid lock? Probably not. I would imagine that attackers will just lock onto maximum noise rather than maximum signal. May make attacking radars harder though. And I suppose standing near an arcing power line in a war zone might be a bad idea if this becomes common.
BTW, are these things going to play hell with other radio communications?
Re:Anonymous? (Score:5, Interesting)
Will this avoid lock? Probably not. I would imagine that attackers will just lock onto maximum noise rather than maximum signal. May make attacking radars harder though. And I suppose standing near an arcing power line in a war zone might be a bad idea if this becomes common.
BTW, are these things going to play hell with other radio communications?
Won't it make identification problematic though? The big misconception about RW (Radar Warning) sensors is that it they only identify hostile radiation sources when in reality you want to know exactly what is lighting you up even if it is friendly. This has led to some unfortunate incidents. During the Iran-Iraq war the Iranians actually lost some F-14s to Iraqi fighters because the Iranian F-14s had a standard NATO RW unit that did not register the radars of Iraqi Mirage fighters and their Super 530 BVR missiles as a threat. In Europe this was OK since French fighters were not a threat but in the gulf, not so much. I expect the Iranians quickly figured out to change the threat classification of French radar signatures to 'Hostile'. The consequence is that firstly, once all radiation sources on the battle field look like noise, all you'll be able to tell after that situation becomes the norm, is that you are being lit up by an unusually strong source of radio noise. You won't be able to tell if it is friendly or not. Secondly I expect the current crop of anti radiation missile can be fired at a radar source and then lock onto another one if the primary target goes dead or the missile gets confused. For that purpose it would have to do some form of IFF, presumably based on the output of some derivative of a bog standard aircraft RW sensor, like those Iranian F-14s had, so that it does not accidentally choose a friendly radiation source when it picks it's alternate target so if radiation sources, friendly or hostile, all look like noise and the AR missile just gets locked onto strong sources of noise it would be unable to identify the operator of any alternate radiation source and thus unable to choose an alternate target without risking a blue-on-blue incident. I expect that the ROE for engaging radiation sources would be tightened up pretty severely, especially when firing AR missiles at AWAC aircraft.
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That said, this
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Any kind of radiation is detectable so even if the signal isn't clear it may still be detectable. However it may be harder to find the source of the signal if it's obfuscated.
I predict that it won't take long until this attempt at evasion is foiled.
Re:Anonymous? (Score:5, Informative)
Re:Anonymous? (Score:5, Informative)
Even signals below the noise are detectable since any signal will raise the noise level somewhat. So if the noise level is higher at a specific direction for no natural reason occams razor would give that it's something there. And since it's now known that a radar technology exists with this kind of pattern it is detectable. It may take some time to detect it, but it's not impossible.
Re: Anonymous? (Score:1)
It can be harder to have a "specific direction" if there are multiple sources and reflections. Ground clutter is enough of a mess with a known source location and frequency.
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The goal isn't to make radar that is impossible to detect, but radar that is much much harder to detect. The former is basically impossible, the latter is quite achievable. With stealth technology it's always an arms race. Even the F-22 has some radar signature, because it's nearly impossible to eliminate it completely. The goal is simply to be as hard as possible to detect.
If it is below noise floor... (Score:2)
here is a link to such a detection scheme (Score:5, Informative)
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"If a spread spectrum signal is below the noise floor, there's no way of telling that it's even there unless you know the pattern."
That might well work for communications, but for radar, you need to detect a reflection that is down what? maybe 30-40db. RF guys are pretty clever nowadays, but My guess is that they aren't clever enough to dig out a noise like signal much, much, much weaker than the ambient noise.
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It has been a while but can they do like they do for subs - sort of? Something like looking for an absence of noise. If the signal is lower then ambient noise and ambient noise has X-characteristics, won't signal with Y characteristics interfere with X characteristics enough to make a noticed change? I imagine it'd take some work to figure out what it looks like but that it might work to detect it.
I'm not articulating that as well as I'd like. 'Tis early and that's my excuse. But, if it's lower than the noi
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It's possible. A spread spectrum signal is only below the noise floor at each specific frequency. If you know the spectral pattern the transmitter is using (at that moment) then you can coherently sum the signal and find that it's stronger than the noise. If you don't know the pattern, you can't do that.
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Any kind of radiation is detectable so even if the signal isn't clear it may still be detectable.
The thing is that there is a radio background. If you attacked every source of radiation then you would end up attacking electric shavers, power tranformers, computers, mobile phones etc ignoring even the obvious deliberately transmitting things like cell towers.
However it may be harder to find the source of the signal if it's obfuscated.
There's already a tecnology in standard civilian use, CDMA [wikipedia.org], which takes transmit power below the background RF noise floor. This and fast frequency hopping in general (see FHSS article as the closest to an explanation [wikipedia.org]) were developed originally by
Re: Anonymous? (Score:1)
I agree. Response Rossiya? The question to ask here is if this adaptation has actual value and if so how can we mitigate this. Radar detection and ECM would have to adapt. The next question would be if it has value how to integrate this feature into S-400/S-500. The final thought on this would be if such an adaptation can not be countered, changes in doctrine will have to be considered such as the more immediate than deferred use of nuclear weapons. Do not cheer this, your lives may become a lot unsafer as
FHSS (Score:2)
So they discovered FHSS [wikipedia.org]. Good for them!
(Also, they may be able to mask the radar pulses, but "encrypt"? Really?)
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More likely high-rate FFT/IFFT with rotating data, null, and equalization sub-carriers.
Re:FHSS (Score:4, Insightful)
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Normally in noise radars they emit a gaussian noise signal. This has quite good autocorrelation properties and thus can be used as a pulse compression function. Big disadvantage is the very high peak-to-average power, which I guess is what this project is working on. You can certainly detect is using a radiometer, by measuring an increase in background noise. In areas with a lot of RF usage you will probably blend in quite well, the other side will want to be very careful not to fire the anti-radiation miss
Re:FHSS (Score:5, Informative)
It's not just frequency hopping.
Radars have a pattern called Staggered PRF Frame, which is a repeating pattern. and this, along with frequency, pulse width and PRI is used to identify a radar.
We already have frequency agile radars. We can identify them because the other characteristics are still constant.
If you make the frame look like random noise then it just looks like clutter. VERY hard to spot.
This is important because you don't just waste HARMs firing at random clutter, and you certainly don't want to accidentally fire on an unexpected friendly.
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"If you make the frame look like random noise then it just looks like clutter. VERY hard to spot."
It only has to be slightly above the noise floor to be triangulated. The actual modulation is more or less irrelevant so long as the signal last long enough to pinpoint it.
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Oh no doubt, you can get a fix on anything.
But without clear details in the signal, you can't determine if it's friend or foe. And in the land of "friendly fire is not so friendly," that means you need a visual confirmation.
If you have enough unique detail to identify the platform, then you feel a lot more confident hurling a HARM at it.
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Still not new. I was working for Rockwell-Collins back in 2000 and our department went to a lecture from a guy talking about Chinese work on radar. One of the concepts that they were apparently working on was broadcasting broad-spectrum noise and looking for statistical correlations in the return.
Re:FHSS (Score:4, Interesting)
It's been a long time since I was involved with Army radar and encrypted communications (in my case, merely humble air traffic control equipment), but the article intrigued me enough to do a very quick lookup. This article [techlinkcenter.org] isn't very technical, but I can see how it's not simple spread-spectrum radio.
Remember that the information conveyed by radar microwaves is limited; we're primarily interested in reflections (this is "primary radar"; "secondary" radar actually does transmit information; IFF is a type of secondary radar). For a simple radar we know the radar echoes are ours because they come back to our own dish, and match the frequency that we transmitted. They're also incredibly easy to jam.
Frequency hopping on its own makes things harder to jam because the frequencies change in a cryptographic pattern. They can still be jammed if your broadcast a lot of noise over the entire spectrum, but then you limit your own communications. If you can detect the point source, though, you can broadcast a point source over the entire spectrum and still jam them.
What I think I understand about this is that it’s not merely frequency hopping, but the signal modulation is encrypted in a way to evade detection. With a receiver I can detect a typical radar’s 3.4 Ghz signal at -200db (numbers are made up), even if spread across the spectrum, because I know what a 3.4 GHz square wave looks like against the background noise, even if it only appears intermittently on the narrow frequency I’m scanning.
I could try to modulate the signal a different way; maybe a sawtooth, maybe a sine, but a repeating, predictable signal is observable, even with frequency hopping. However if I broadcast noise (and my receiver knows the noise’ pattern), then any listening equipment shouldn’t be able to pick out my microwave pattern from the background.
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This is a modification of noise radar intended to make the signals even harder to detect as far as I can tell. While I wouldn't call the signal encrypted it is still true one have to have the "key" to make sense of the radar return. That and a extreme amount of processing power!
Most useful applications 2.0 (Score:3)
Catching speeders.... since vehicle radar detectors won't work for attempting to detect the the encrypted radar signal.
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Jamming is more effective for protecting motorists. Thanks to the development of collision warning and autonomous vehicles it's not perfectly justifiable to mount IR lasers and radar on your car. Police speed guns only interfere with important safety equipment, increasing the probability of an accident.
In any case, most mobile speed traps use lasers, not radar. The fixed ones are no problem because it's easy to keep a database of where they are - my Nissan came with one built in, and a handy voice prompt wa
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Catching speeders.... since vehicle radar detectors won't work for attempting to detect the the encrypted radar signal.
Probably irrelevant due to deployment of average speed cameras anyway...
Backdoor (Score:2)
The FBI have already asked for a back door.
Probably using a CHAMP-WB (Score:2)
I just ordered (for my radio astronomy job) its cousin, which is all A/D converter, as our radio telescope doesn't have a transmitter, just a receiver.
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The US Army operates mobile radar stations that are either towed or mounted on a truck. That seems like the perfect candidate for a stealth radar.
Will the FBI get a backdoor? (Score:2)
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That's a nice idea but doesn't address the real issue for most users - they have no way to evaluate updates. The manufacturer tells them that the update is important and makes their vehicle more secure, and they should apply it immediately, and their warranty will be invalid if they don't. At best they can search the internet and get a bunch of crap from clueless reddit posts and tweaker forums. Meanwhile someone is hacking their car because they didn't patch the 0-day exploit.
As for data collection, my Lea
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Re:Here's an idea (Score:4, Funny)
It's a spread-spectrum post.
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You're right. First time I've done that. I feel I've accomplished something.
why? (Score:1)
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Because it's obvious, anyone in the know probably already has kit that does this, it's in no way a secret, or new, or otherwise unavailable, and all possible opponents are deploying this already.
But if you make it sound new and exciting, people in the US won't question why they spend more on the military than ANY THING ELSE, EVER, despite not even being at war, and they'll think you're doing things that nobody else has ever done, that sound cool, and so they won't mind frittering money away.
Not new (Score:1)
https://en.wikipedia.org/wiki/Low_probability_of_intercept_radar
Similar systems are already deployed. The original implementations were a variation on frequency hopping techniques, but they've been becoming more sophisticated as computing power increases.
It makes them harder to detect, harder to determine the source if detected, and more resistant to jamming. They can still be rendered useless by powerful broadband jamming, but that is rarely used as it blinds everyone, not just the enemy. Though it sho
Cat and mouse game (Score:1)
Radar detectors would have to adopt Counter LPI/LPD techniques, which apparently do exist:
There's a book on Amazon called "Detecting and Classifying Low Probability of Intercept Radar".
Open source it! (Score:2)
This sounds like it could be beneficial in many areas of signal transmission. I feel it should be opened to the public.
The last thing we need is more military capability. In fact, what we really need is more technically capable adversaries to keep us in check and raise the real cost of us going to war to untenable levels.
So the real answer is ALL of our defense research should be opened to all of mankind. Every last page of it. I would LOVE to see this technology used in commercial drones, in the hands of t
NOT innovative at all! (Score:2)
Hedy LaMarr (yes) developed spread spectrum frequency hopping for submarine torpedo guidance systems that couldn't be intercepted by the enemy who would then have been able to throw the torpedoes off course. She patented it in 1942. The US Navy started deploying her system in the 1960s during the Cuban missile crisis.
The same technology gives us WiFi, CTCSS/DCSS, FTTC, n-plexing NFM and WFM radio, CDMA, Bluetooth...
What's the novelty? (Score:2)
Can anyone with access to the papers share what's new about "advanced pulse compression noise" radar versus classic noise radar?
Noise radar itself, i.e. transmitting white noise and then correlating returns with the original noise signal to find the targets, is not a new technology. I don't doubt there's something new here, but the articles are too light on details to be able to tell what.
Also, bit of a stretch to call it "encryption"... Methinks that was the managers or the journalists.
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I was doing that in 1973. But everything in radar repeats at about a 12 year cycle, and that's about the fourth time coded signals have been hailed as revolutionary. The problem is that, if you plug the parameters needed into the radar range equation, the radar receiver needs a lot more sensitivity than the target's radar warning receiver because it's the inverse of the fourth power of the power transmitted vs. the second power at the target. Chopping it into noise-like stuff helps somewhat but you still ne
Encryption algorithms (Score:1)