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MIT Researchers Can See Through Walls Using Wi-Fi

Posted by timothy on from the upgrade-your-router dept.

itwbennett writes "MIT Professor Dina Katabi and graduate student Fadel Adib have developed a system they call Wi-Vi that uses Wi-Fi signals to visualize moving forms behind walls. How it works: 'Wi-Vi transmits two Wi-Fi signals, one of which is the inverse of the other. When one signal hits a stationary object, the other cancels it out. But because of the way the signals are encoded, they don't cancel each other out for moving objects. That makes the reflections from a moving person visible despite the wall between that person and the Wi-Vi device. Wi-Vi can translate those faint reflections into a real-time display of the person's movements.'"

22 of 75 comments (clear)

  1. its called radar by Anonymous Coward · · Score: 5, Informative

    It's not exactly new either. The only difference here seems to be that the radar signal source is just a low power wifi AP. Yawn.

    1. Re:its called radar by K.+S.+Kyosuke · · Score: 2

      MIT has already been doing some nice experiments with WiFi/microwave oven/ISM band radars. I wonder if this isn't an extension of their previous projects. Using unmodified WiFi electronics seems to be a neat trick, though.

      --
      Ezekiel 23:20
    2. Re:its called radar by Anonymous Coward · · Score: 5, Informative

      Standard radar cannot see through walls because the receiver is overwhelmed by the wall reflection (its ADC is saturated). According to the authors, this is a very well known challenge and is called the "Flash" effect. Wi-Vi's new nulling algorithm solves that problem, enabling for the first time narrowband RF to overcome this effect. This link explains their technique: http://people.csail.mit.edu/fadel/wivi/design.html

    3. Re:its called radar by peragrin · · Score: 2

      they can tell the difference between moving and non moving objects.

      The next version will be able to tell the difference in general materials, brick, stone, sheetrock, wood, warm bags of no longer potable water.

      The version after that will introduce portability. and thus the tricorder will be born.

      --
      i thought once I was found, but it was only a dream.
  2. Misleading headline by Anonymous Coward · · Score: 2, Insightful

    Headline should have been "MIT Researchers Can Track Movement Behind Walls Using Wi-Fi".

    1. Re:Misleading headline by gl4ss · · Score: 2

      Headline should have been "MIT Researchers Can Track Movement Behind Walls Using Wi-Fi".

      but then it sounds suspiciously similar to an older headline on the same subject. and is rather boring.

      --
      world was created 5 seconds before this post as it is.
  3. Code source or it didn't happen by kk49 · · Score: 2

    Gimme! Please :)

    --
    You can have your god back when you are old enough to handle the responsibility.
    1. Re:Code source or it didn't happen by kk49 · · Score: 5, Informative

      The paper http://people.csail.mit.edu/fadel/papers/wivi-paper.pdf

      --
      You can have your god back when you are old enough to handle the responsibility.
    2. Re:Code source or it didn't happen by kk49 · · Score: 2

      It was done with USRPs (http://www.ettus.com/ which are awesome) and one of the WiFi encoding schemes, not with standard WiFi hardware :(

      --
      You can have your god back when you are old enough to handle the responsibility.
    3. Re:Code source or it didn't happen by citizenr · · Score: 2

      you will need 3 x USRP first

      Its not WiFi. They could of named it seeing through walls using Microwave Oven and be as accurate as now.

      --
      Who logs in to gdm? Not I, said the duck.
    4. Re:Code source or it didn't happen by kk49 · · Score: 3, Interesting

      Ya :( This was better http://hackaday.com/2012/12/18/build-a-360-synthetic-aperture-radar-with-mits-opencourseware/

      --
      You can have your god back when you are old enough to handle the responsibility.
    5. Re:Code source or it didn't happen by wagnerrp · · Score: 3, Interesting

      While it's nice projects like this open up such technologies to hobbyists, the article is documenting something very novel. Traditional RADAR has trouble seeing through walls, as it cannot filter out all the noise from the wall's reflection. By sending two specially encoded signals that cancel each other out against stationary objects, they've sidestepped this issue entirely, and come up with something brand new. They've developed the much wanted Sci-Fi trope of a portable motion detector.

  4. NSA Use by Oysterville · · Score: 2

    So then I guess we should be looking into ways to prevent government agencies from using this against us. They've already proven to be completely incapable of trustworthiness.

    1. Re:NSA Use by Anarchduke · · Score: 5, Informative

      How is that? They are entirely trustworthy; they do what we tell them to do. We gave them every bit of authority they use to spy on us. We threw our privacy at them and cried, "Take this! Save us from the terrorists and spy upon us!"

      --
      who prays for Satan? Who in 18 centuries has had the humanity to pray for the 1 sinner that needed it most? ~Mark Twain
    2. Re:NSA Use by Trepidity · · Score: 3, Interesting

      When it comes to viewing the movement of humans through walls, there have already been infrared cameras for years, which in most situations will do anything this wifi approach can do and more. The only real advantage of this wifi approach is that it's cheaper, using ubiquitous commodity hardware.

      So when it comes to government agencies, this doesn't really change the technological situation: they've already had the ability to track movement through walls for years. They're only restricted in using it to the extent that legal restraints are successful. For example in Kyllo v. United States the Supreme Court threw out a conviction that was obtained in part by using infrared cameras to look inside a home without a warrant.

      --
      10 PRINT CHR$(205.5+RND(1)); : GOTO 10
  5. :O by Hunterhawk · · Score: 2

    Sweet I can finally watch my neighbors T.V. And to think people used to use WINDOWS! hah! so crude.

  6. Not Wi-fi by wisnoskij · · Score: 4, Informative

    I am sure they are using the same frequencies as wi-fi. But wi-fi is not just the use of a certain frequency range.

    --
    Troll is not a replacement for I disagree.
    1. Re:Not Wi-fi by dissy · · Score: 2

      It looks like they are using standard wifi hardware, two modules actually.
      What they aren't doing is speaking 802.11 over it and are providing their own framing in order to get a reversed signal on the other module. There will be no protocol in that framing to speak IP on top of.

      The major advantage is that a manufacturer can purchase the same wifi chips as they usually do for wifi, but these two chips are configured in software quite differently. I assume they will likely have a different antenna to optimize it for this function too, since the hardware modules will be dedicated to this task.

      That's also probably why they don't call this "wifi" at all. (Go go gadget slashdot reporting!)

      While it might be possible in some existing devices to reconfigure the existing wifi chip to work in this way, you must have two in total for the task or it won't work, so most existing devices will be excluded due to that reason alone. Of course any antenna issues will make it sub-par, and also you won't be able to use a chip for both this and wifi at the same time which would be very handy for a remote sensor type device.
      Most likely, any new hardware built for this purpose will come with a total of 3 hardware wifi modules, one dedicated to 802.11 and the other two dedicated to wivi.

      Using existing mass-produced hardware will let maufacturers take advantage of both the low cost of those modules, and the fact they likely have them in their ordering system with bulk pricing deals setup already.
      Previously one needed dedicated sonar or radar hardware, which isn't in as large of demand and so still pretty expensive.

  7. Cop-out by Dcnjoe60 · · Score: 2

    What a cop-out! From the article "Like all technologies in the world, it depends on us how we use them," Katabi said.

    People use that excuse all the time. However, when one has a reasonable expectation as to how some technology will be used, you cannot fall back on this reasoning to ease one's conscious over their own culbability in something. The scientists involved in the Manhatten project new full well how that technology would be used and had to deal with the moral implications. Today, though, the notion is technology for technology's sake with no thought of the consequences.

    Well here's news to all my fellow researchers, if you develop some new technology, great, but don't hide behind your mommy's skirts and say, something like the above. You know darn well how it will be used, so take responsibility for it.

    1. Re:Cop-out by Dcnjoe60 · · Score: 2

      Any technology that has been invented, eventually would have been (because we now know it's possible). While not a direct quote, it's what Edward Teller said more or less of the Hydrogen Bomb. That, and we would have been speaking Russian now had we (the US) not pursued the H-Bomb program.

      That is true, but some technologies are much more readily apparent as to their misuse than others. Splitting the atom is a good example. It is hard to think of peaceful applications of such a technology (which is different from, say, nuclear power). In the past 40 years or so, science has focussed more and more on can we do such and such and ignored the question of should we be doing such and such.

      However, we scientists can not hide behind the moral argument that we are only inventing technology it isn't up to us how it is used, any more than the Nazi solders could claim they were only following orders. Scientific discovery has the power for good and evil and to ignore the potential of evil, particularly if it far outweighs the good is either a sign of moral weakness or culpability.

      This doesn't just apply to scientific research, but all forms of engineering and product development in our society. I am quite confident that we could put a 500hp engine in a vehicle the size of a Fiat 500. The capability is there, but should we do that? Such an overpowered vehicle would be a death trap and the only thing that keeps a manufacturer from doing so is the liability claims would outweigh the profits from such a vehicle. Auto manufacturers aren't allowed to hide behind we only build the car, its up to people how they use it (although gun manufactures do use that thought pattern). But, for scientific research, it is acceptable.

      MIT developed a new way to track people inside buildings that the only really useful and practical application is for surveillance. There is nothing wrong with that, until they come out downplaying that use and trying to say how it will actually help make privacy even better (in the article). Knowing that is a losing battle, and evidently feeling ashamed of their discovery, they then fall back on the old we only invented it, it's not up to us how people use it.

      If Snowden had released that the NSA was already doing this, people would be outraged. But then MIT isn't responsible for how the government uses the surveillance technology they develop. Maybe they should require all those MIT students to take some basic philosophy and ethics courses. It would be helpful if the brightest minds in the country could tell right from wrong and how to take responsibility for what they are doing.

  8. Re:in other news by neonsignal · · Score: 2

    It's somewhat more difficult than just 'seeing through things'; walls are not totally transparent to the wavelengths of interest, and reflections from them dominate the signal. Moreover, this technique makes use of equipment that can't do the precise timing of radar measurements (though this means they can only track the angles of moving targets, not their position). It is a neat sort of hack, and interesting for that reason.

  9. Just like T-Rex by Megahard · · Score: 4, Funny

    It can't see you if you don't move.

    --
    I eat only the real part of complex carbohydrates.