Seeing Through Walls 163
An anonymous reader writes "Researchers at MIT's Lincoln Lab have developed new radar technology that provides real-time video of what's going on behind solid walls. 'The researchers’ device is an unassuming array of antenna arranged into two rows — eight receiving elements on top, 13 transmitting ones below — and some computing equipment, all mounted onto a movable cart. But it has powerful implications for military operations, especially "urban combat situations," says Gregory Charvat, technical staff at Lincoln Lab and the leader of the project.' ... each time the waves hit the wall, the concrete blocks more than 99 percent of them from passing through. And that’s only half the battle: Once the waves bounce off any targets, they must pass back through the wall to reach the radar’s receivers — and again, 99 percent don’t make it. By the time it hits the receivers, the signal is reduced to about 0.0025 percent of its original strength. But according to Charvat, signal loss from the wall is not even the main challenge. "[Signal] amplifiers are cheap," he says. What has been difficult for through-wall radar systems is achieving the speed, resolution and range necessary to be useful in real time (PDF).'"
So what if your standing IN FRONT of the wall? (Score:4, Interesting)
Is the amount of radiation dangerous? What about reflections? Not that it would matter in a military context but it might restrict its civilian applications.
Re:So what if your standing IN FRONT of the wall? (Score:5, Informative)
Re:So what if your standing IN FRONT of the wall? (Score:4, Informative)
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does it really matter? we are talking about the military using this to find people behind walls to they can kill them more effectively.
Really? You really think that's all this is going to be used for? How naive.
The natives are becoming restless, they need stuff like this to quell a rebellion, flush out the leaders, and protect the establishment. They've already started rolling out unmanned drones [homelandse...wswire.com] for use by the police. They could start deploying the armed versions whenever they want.
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does it really matter? we are talking about the military using this to find people behind walls
You are naive enough to believe that this will never be used by the government on civilians EVER, right? The military doesn't really need something like this because if they are really worried about what's behind a wall they just blow it up. This is 100% for law enforcement use, which is where the government wants to know what's behind the wall but is not allowed to do so by law.
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Eh? As you said, it's non-ionizing. The heat is the radiation damage.
Sounds more like a feature than a bug. Remember: military applications.
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Non-ionizing means that it does not directly cause DNA damage.
However, it has been shown in tests that microwaves of certain frequencies can have other effects on human cells other than heating them up. These effects include increasing the uptake of glucose and breaking the cell's membrane which would allow the cell to be killed by albumen in the blood.
Not all frequencies in the microwave band are equal, though. Only some frequencies have been tested.
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These effects include increasing the uptake of glucose...
That's it. I'm suing the government for my obesity.
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No, no, no. The CORPORATIONS are responsible for your obesity. The Government is doing their best to protect you from the evil corporations (and from yourself). Just let them do their job and you'll be fine.
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Have you seen this [peswiki.com]?
So much for non-ionizing radiation doesn't ionize.
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Sure if you want to save the military their next step.
Re:So what if your standing IN FRONT of the wall? (Score:5, Informative)
It's non-ionizing radiation so it's about as dangerous as your cellphone. This is an interesting and informative radiation chart https://www.xkcd.com/radiation/ [xkcd.com]
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I don't know the power of the apparatus being tested in the article, but the person walking around was behind a wall, which reduces the dose to 1%.
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I don't know the power of the apparatus being tested in the article, but the person walking around was behind a wall, which reduces the dose to 1%.
Which is still 100 times larger than is needed for regular detecting equipment, as the "dose" needs to cross the wall again. So the "other side" dose is still significantly strong.
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I doubt if it's 100 times larger. I don't have time to compare, but it will be a lot less. One trick to reduce the wattage is to take much more time measuring, and a predecessor of the radar in the article took many seconds. This radar also measures slower than the standard.
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Obviously. And also you don't need cooking temperature.
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many proteins denaturate over 41 degrees celsius. It might be reversible when the temperature is not too high though. If you heat part of the body with microwaves up to 50 degrees celsius, that could already do a lot of permanent damage. And I doubt if you'll feel much heat when it happens.
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many proteins denaturate over 41 degrees celsius. It might be reversible when the temperature is not too high though. If you heat part of the body with microwaves up to 50 degrees celsius, that could already do a lot of permanent damage. And I doubt if you'll feel much heat when it happens.
Your core temperature is 37 C (98.6 F). But you don't think someone would notice 50 C (122 F)? If that was bathwater, you'd be scalded.
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I wonder. Skin is always a bit different. What temperature would you consider too hot for tea? 60 degrees is well acceptable then. But then you drink it in small quantities that cool down quickly.
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FUCKEN MICROWAVES, HOW DO THEY WORK?!
Actually, microwaves are made from unicorns and enchanted hobbits, so technically they are, in a sense, made of magic.
They cook oils only on the surface because the resonant frequency is a good match. This is the cause of much of the food spattering in a microwave oven. The heat will pass gradually into the oil from the surface by convection, but the surface gets a LOT of heat by absorption. Much food has a high water content... and microwaves will heat water, but are
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By the way, I'm sorry for the incorrect used of the word your, it should be you're as in "you are". I dislike it when people use it incorrectly so my apologies. I was in a hurry (but aren't we all?)
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They were walking around in front of it. Leads me to believe it's not particularly dangerous.
People used to go down to Vegas for the weekend to watch the atomic bombs going off...
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Yes, but in this case the "people" are the actual researchers, no some random Joe.
Aluminum Foil (Score:5, Funny)
In the future, I guess snipers will have to carry a $ 5 roll of aluminum foil, to block the multimillion dollar real time radar.
Re:Aluminum Foil (Score:4, Insightful)
In the future, I guess snipers will have to carry a $ 5 roll of aluminum foil, to block the multimillion dollar real time radar.
Which would shine conspicuously in the radar beam. That's where I'd shoot.
Re:Aluminum Foil (Score:4, Insightful)
Crinkle it up.
Re:Aluminum Foil (Score:4, Interesting)
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In the future, I guess snipers will have to carry a $ 5 roll of aluminum foil, to block the multimillion dollar real time radar.
Which would shine conspicuously in the radar beam. That's where I'd shoot.
Its a trailer park, or the enemy would make everyone put foil on their windows.
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In the future, I guess snipers will have to carry a $ 5 roll of aluminum foil, to block the multimillion dollar real time radar.
Which would shine conspicuously in the radar beam. That's where I'd shoot.
Ok, so $5 foil and $3 blu-tak, so you can put it on the wall you're hiding behind.
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What if the whole wall has a layer of aluminum sheeting inside?
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Luckily the xenomorph don't have aluminum foil, so this motion tracker is still good.
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A fridge is all you need
http://www.youtube.com/watch?v=YNJ4c0B-s1Y [youtube.com]
Just before the 8 minute mark
Re:Aluminum Foil (Score:4, Insightful)
Or maybe the $10 microwave detector so when they get an alarm they start shooting at the truckload of equipment outside their house.
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Shooting? Just hook it up to a bomb.
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Yes, because a roll of aluminum foil can easily wallpaper an entire room
As other posters pointed out, you don't need to do the whole room.
aluminum foil is readily available in war zones
Neither are fertilizer, aluminum powder, potassium chlorate, and other elements used to make IEDs in Afghanistan. They ship it in. Ammonium Nitrate has gone from about $7/40 lbs bag to over $100 in Afghanistan, and it's still being used. If it's an essential material that will save their lives or kill their enemies, they'll get it.
Moreover, snipers will carry enough foil to wallpaper the multiple rooms they displace to after shooting once.
If it's necessary, yes. You should see the extreme methods used to circumvent our equipment in Afghanistan. If it
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I know a sniper who carries an umbrella (to block IR sensors). I think they can get their hands on aluminum foil. In fact, I think that they could get whatever they think they need.
Cool (Score:5, Interesting)
A) This is different than x-ray because it is using the reflection, not a film or detector on the other side of the object.
C) The image created is not a 3D image like what you would expect if the wall were glass, instead it detects distance to objects. So what you get is like a overhead map, as if you were playing Zelda and or had the Harry Potter marauder's map. Which may be more useful in some situations.
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Bad news for conspirationists though: Tinfoil hats will be very easy to spot and to be taken care of. Might want to invest in a radar detector though.
Re:Cool (Score:5, Informative)
It was a linear phased array. It literally can't tell up from down. If you wanted to make it sense in 3-D, you would have to make the array 2-D. Stack a couple of these units, throw in a couple more GPUs for processing, re-tweak the algorithm for an additional dimension, they could probably have a 3D model working in a couple weeks.
The issue is that 3D really doesn't get you much. With the current 2D system, you can tell where someone is in a room, but its not like you can see any identifying features. All 3D would get you is a very rough estimate of height.
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Two points:
A) This is different than x-ray because it is using the reflection, not a film or detector on the other side of the object.
C) The image created is not a 3D image like what you would expect if the wall were glass, instead it detects distance to objects. So what you get is like a overhead map, as if you were playing Zelda and or had the Harry Potter marauder's map. Which may be more useful in some situations.
B) Somebody uses a Dvorak keyboard!
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Why would you do A, C if you used a Dvorak keyboard?
That ruins the use of (Score:2)
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Call of Duty (Score:3, Funny)
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Spaceballs- Barf: "Radar about to be jammed!" (Score:2)
So, will my microwave oven jam this thing up? Cook lots of hot microwaved burritos and keep Big Brother from watching you? When will I get my glasses that let me see through clothes, see my own bones, etc? Remember those? They were on the opposite side of Sea Monkeys.
Also, time to bring the radar detector inside so you know when to step out and unload some buckshot? Or just wire your radar detector into your homemade rocket and "nuke it" from a couple of blocks over?
Stuff the walls with tinfoil? Or build yo
Prior Art (Score:2)
solid wals, as compared to what other walls? (Score:2)
"what's going on behind solid walls."
Of course, what is going on behind liquid walls will remain a mystery.
"signal loss from the wall is not even the main challenge. '[Signal] amplifiers are cheap,' he says. What has been difficult for through-wall radar systems is achieving the speed, resolution and range necessary to be useful in real time"
Of course, the main problem in achieving the "speed, resolution and range" is that you lose 99% of the signal, twice.
In other words, signal loss is not the main problem
Is it really that useful? (Score:3)
So it is good at locating people moving behind a wall. Can you tell if the person is armed?
If you also display stationary objects, is the blob in the corner a person or a filing cabinet?
Look at the size of the thing. I do not see a tactical unit trundling something that big so that they can see 20m through a wall. I am not sure but if you decrease the size of the antennas your power and resolution goes down. Also how much power does the radar and computers use? How long would it last on batteries?
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Even if they weren't armed, you could always place a pistol in their hands post-factum.
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It seems like something that could be extremely useful for scouting a room in a hostage rescue situation: you know the bad guys are in this room, but you want more info on where. Of course, they could probably use a fiber optic camera for that in most cases.
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The only issue with a fibre optic camera is that it needs a hole to look through. It is quite possible that the drilling through the concrete wall could be heard.
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I was talking about the size of the phased array antenna. The multiple antennas need to be separated by a certain distance so they do not interfere with each other and need to be a certain size so they can gather enough radiation. That's the physics of radar and no research is going to change that. Phased array radar is not new technology; it came out on the Ticonderoga class cruiser in 1978. One would think that they would have made the array as small as possible in the first place
The real question (Score:2)
Does this system run on "Windows"?
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No, the real question is: Can we look with this through the blonde bomb shells clothes...
That would be convenient to spot girls with a tramp stamp before it's too late (one way or the other).
Fourth Amendment vs DHS (Score:2, Insightful)
This technology is unconstitutional. I have zero faith the arrogant slashdot crowd to actually comprehend it until it's too late. It's all fun and games until someone's eye get's put out.
The Fourth Amendment (Amendment IV) to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures, along with requiring any warrant to be judicially sanctioned and supported by probable cause. It was adopted as a response to the abuse of the writ of assistance,
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Thank you, sir. You're encouraging me to join the "OWS" groups and help them avoid being co-opted.
Mod. Parent. UP.
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While some of your objections against such technology's possible uses are understandable, the technology is not to blame. What we already have: miniature cameras and insane U.S. building standards will let anyone spy on anyone else anyway, right now, with much simpler tech.
For non-U.S. dwellers: a typical recent U.S. single-family residential building's wall consists of, going inside out: paint, drywall, plastic vapor block, vertical wood studs with fiberglass insulation between them, foam board "sheeting",
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the technology is not to blame
So true.
Unconstitutional searches can be done with nothing more than one's eyes, or by breaking in a door and searching using a sledgehammer and searching. It's not the technology that makes a search bad, it's the people that are doing it and their willingness to disregard the fourth amendment.
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This is the path to darkness, death, destruction and marital law.
As the son of a lawyer who handled a lot of divorce work, I have to say that was one of the funniest typos I've encountered in a long time.
You're mostly right about the rest of your post though. The thing I want to point out, though, is that many of the civilian population are justifiably afraid that if they do something about what's going on, they'll lose any chance of working, which means they'll (soon, once the 2012 election is done) lose their ability to feed, clothe, and house themselves and their kids
Military (Score:2)
But it has powerful implications for military operations, especially "urban combat situations,"
Oh, yes, that's where it will be used. No way they would EVER use it against their own people.
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Like IR cameras, it would soon be banned from doing illegal searches.
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Like IR cameras, it would soon be banned from doing illegal searches.
Those aren't banned at all. They just can't use the results of car-based cameras as evidence in court. They still use the ones in helicopters to conduct raids, and I'm sure they use them in plenty of other circumstances, too.
Of course, all they need these days is a grant from DHS and a claim that they are looking for "terrorists", and they can do whatever they want. No court even needed, once they ship you off to Gitmo.
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Like IR cameras, it would soon be banned from doing illegal searches.
Thought I'd follow up with this little tidbit, from a story about the SCOTUS case you're referring to [go.com]:
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There is a huge difference between an illegal warrantless search, which I was referring to, and a search sanctioned by a warrant. With a warrant the police have a judge's permission to look into a building. Whether it is done by radar, IR or eyeballs makes no difference. So no, the police are not going to be driving down the street scanning random people in their houses.
As a ERT tool this is a good one. It could be used before a search warrant is executed to locate all people in the house and possibly decre
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When executing a warrant all reasonable tools should be used.
The police state in the US is WAY beyond using anything resembling that kind of restraint. They are now accepting collateral deaths of police and innocent civilians as justified to combat recreational drug use. Expansion of those powers in the name of fighting "lone wolf terrorists" is a frightening prospect.
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Interesting how you neglect to mention the deaths of police and innocent civilians caused by the purveyors of recreational drugs. Some of the deaths of innocent civilians occur when two purveyors of recreational drugs fight over the same territory. There are many documented cases of drug gangs having and carrying automatic weapons and assault rifles. So when the police have to deal with these gangs that do so using heavily armed, highly trained units. If you don't want to get shot when an SRU shows up then
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Interesting how you neglect to mention the deaths of police and innocent civilians caused by the purveyors of recreational drugs.
Because it's irrelevant to the discussion. Those are not actions sanctioned by the state (although the state's very prohibitionist stance on recreational drugs has certainly precipitated the environment in which black marketeers become violently defensive of their activities).
So when the police have to deal with these gangs that do so using heavily armed, highly trained units.
I won't excuse the actions of the state when they have created the very atmosphere of violence they are claiming to combat.
If you don't want to get shot when an SRU shows up then don't pull a gun.
That doesn't help most of the time [cato.org], and especially when you aren't given an opportunity to identify the group t
I can't wait (Score:2)
Extension of an earlier story (Score:3)
http://hardware.slashdot.org/story/10/06/18/1350259/diy-synthetic-aperture-radar [slashdot.org]
Also on his blog, you will see similarities to what he developed for his PhD and what he is working on now.
http://www.mit.edu/~gr20603/Dr.%20Gregory%20L.%20Charvat%20Projects/Synthetic%20Aperture%20Radar%20(SAR).html [mit.edu]
Oh, and I am not a groupie. I happen to actually know Greg.
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Since you seem to know something about it, maybe you could answer this: why is this suddenly such a big deal? I thought the original article was a big deal because he'd made synthetic aperture radar out of stuff he picked up on ebay -- it was a really amazing DIY hack, in other words. But militaries have had SAR for decades, right? So how is what he's doing different than what's been available for many years? Obviously it is, because this is making news all over the place, but I feel like I'm missing so
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Seen in science fiction (Score:2)
There was a similar device in a sci-fi novel I read some decades ago, I forget the name but it might possibly have been California Dreamtime. Anyway, an assassin (bad guy) equipped with super advanced milspec tools is stalking someone and has a sonar device on his belt and contact lens displays. I wonder if sonar, or perhaps a laser scanner (as typically available for robots, but at microwave or terahertz frequencies) wouldn't be better than radar.
Will it work for all walls? (Score:2)
The w
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There are no frequency differences from the echos from stationary objects. They use beamforming/SAR techniques to get a stationary antenna to form a 2D image in downrange/crossrange coordinates (far/near vs sideways). There's no imaging along the top-bottom direction, although that's not a big issue: all they'd need is to replicate their linear antenna into a 2D antenna. The echo from the wall is still there, but they simply subtract a reference radar image from current image. If you stand very still, the r
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Hmm, I've re-read the article and it does seem like they use a filter to get rid of some of the wall echoes. They say it's their way of doing range gate, and I only imagine it's because the transmitted pulse is frequency-chirped. The earlier reflections will have different frequency than the later ones, so they essentially shift a time domain problem into frequency domain by sending out a time-dependent frequency signal.
Star Wars FTW (Score:2)
See page 554 in TFA [mit.edu]. They image a guy holding a metal rod. The name of the output file in the screenshot? StarwarsKid. Yay!
Mount it on a helicopter! (Score:2)
I don't know why most people assume that this will be attached to a truck, or moved my hand. If I were the military first thing I would want to use it for is helicopter surveillance. You would have to make it more powerful to work at reasonable elevation, and would probably want to widen the field of view. Not easy tasks I'm sure.
But suppose that you could fly around in a helicopter higher and faster than "likely to get shot down by rifle fire" speed/range or at night. You could scan large swaths of houses
isn't this what windows do? (Score:2)
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In English, they are called X rays (which is actually the name Röntgen gave to them).
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Although the truck is disguised, you can tell they're there when they put the giant piece of film up on the other side of the house.
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Re:Pivot That View (Score:5, Informative)
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With a 20cm signal, you can't tell a human from an amorphous blob.
Some people are amorphous blobs.
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There goes my hope for a highly sophisticated perv-o-cam. For now I'll have to make do with hanging out around the airport scanners.
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Sprint is for seeing inside walls not through them in real time.
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Sure, but you are dealing with urban combat in which HARMs aren't really a concern. When you jam GPS you would usually be trying to stop missiles and bombers from getting you - an environment in which HARMs are certainly going to be involved.
If the other side using such missiles against your infantry you are not fighting house to house and room to room anyway. You are still levelling them from the air.
Re:What they don't tell you (Score:4, Informative)
It's called coherent integration gain. It's done entirely digitally in a modern radar such as this and can in theory allow you to detect pretty much any signal no matter how weak [there are practical limits of course...] The whole radar they've described probably has a BOM cost of less than $200,000. The real gotcha is labor to make it work, not the material cost. That'll cost millions [probably >$10Million, you could find out if you want to dig through some defense contracts and find the value of this one...] but so did your new iPhone 4S. The difference is that your iPhone 4S is going to have millions made this not so much. If the government wanted to build 100,000 of these, the cost would probably drop to around $50,000....
Here's the idea:
1) You transmit N identical pulses of radar waveform (probably an LFM or NLFM waveform for this application)
2) They bounce off the target and return to the radar
3) You receive them. They are WAY below the noise figure (say 50db). No amount of normal filtering will get them back. You have to analyze the noise for something that isn't "noise" like....
4) You use a matched filter that has a maximum output when the input signal is exactly the LFM you originally sampled to "pulse" compress the signal
5) If you're lucky the matched filter output has gotten you 20-30 db of gain because it's looking on a single pulse basis for the exact signal of interest. That 20-30db gain DOESN'T apply to the noise, because the noise won't match the matched filter [random vs determinisitic], therefore you've gained 20-30db of SNR.
6) Now remember you transmitted N pulses. Why not look for a signal across all of those? That's the next step. For this application they'd probably use Doppler processing. Turns out that if you do this properly you get gain on the desired signal equal to the number of pulses, so if you transmit thousands you can get that remaining 20-30db needed to make the signal >15db SNR which is the usual minimum for reliable detection in thermal noise.
It's really straight forward. The challenges here are not in that part of the design. That part is easy..
The challenges are:
1) Making it realtime (Coherent processing doesn't work when targets lose coherency that happens when they move "too quickly"). This limits the number of pulses you can use to make useable system
2) Dealing with the Dynamic range between the (very) STRONG wall return and the very weak internal targets. [Very expensive ADCs and RF amplifiers can help, they've also apparently added a doppler filtering step in analog which is interesting.... But fundamentally it's a pain]
3) Target classification. The military could care less how many TV and appliances you have. Unfortunately those will show up as targets behind the wall too...
4) Making it small enough and draw a reasonable enough amount of power to be vehicle mounted
===> If you fix #1 with more output power or a larger antenna you run into this problem.....
4) Having enough resolution to actually differentiate 2 separate targets. Without going into the details this becomes problematic for short range radars like this....because you want to see things that are on order 1ft x 1ft.. Radar is much better at seeing Planes and Tanks...
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I think if they had a wider bandwidth ADC they could get rid of the analog Doppler filter. Eventually the oversampling in the ADC would give them back the dynamic range they need. They used about as basic of an A/D card as it gets. The BOM is way less than $200k I'm sure. The boards for the antennas probably aren't cheap due to their size, and I don't know if they are FR-4 or Rogers. They'd probably cost $2k or so on a 1 week turnaround, probably less. The RF components and cables can be scavenged off eBay
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This is not a multi-billion dollar project. With a bit of resourcefullness, you could do it yourself for under $2k in hardware, assuming you've got a good PC and a decently instrumented electronics workbench. There's no magic "millions of dollars worth of noise cancellation equipment" -- it exists in silly movies only. Either you are above or below noise floor, and even if you're below you can employ averaging to trade off bandwidth (in the sense of frame rate) for SNR improvement. Heck, they do a lot multi
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The ReTWIS has lower resolution than this project, it'd seem, and it's similarly a 1D antenna system only to provide a cross-sectional view.
The Xaver 800 seems to have comparable resolution and 2D antenna to provide 3D imaging, but is using much higher-tech approach. TFA is a system you can easily homebrew if you have RF experience, the Xaver 800 -- not so much.