What is tomographic motion detection?

Posted on Sunday, June 23rd, 2013 in security, sensors, wireless by the machinegeek

Recognizing the shortcomings of traditional PIR and ultrasonic sensors used in alarm systems, security researcher Connected Ape decided to explore other options. He discovered this patent for a mesh system of RF nodes, designed to detect the presence of humans based on changes in the baseline signal strength between nodes. While such commercial systems are more costly, their advantage is the ability to pass through walls, furniture and other obstructions. This principle is implemented using signals in the 2.4 GHz range, and is found in systems such as those from Xandem which use the TI CC2540 RF SoC.

You can find more information and links in the post at Cybergibbon’s blog.

This entry was posted on Sunday, June 23rd, 2013 at 2:00 pm and is filed under security, sensors, wireless. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

11 Responses to “What is tomographic motion detection?”

  1. Bertho says:

    So, building this baby, or a derivative, may get you into the patent wars. I think that DP should be very careful posting patent encumbered systems.

  2. Tracy Hall says:

    Why not publish? A patent is the right to exploit commercially, not the right to keep secret. Courts have *long* affirmed the right to reproduce patented inventions in the lab. Selling a kit to recreate the invention *might* (it’s not entirely settled case law) be a problem, but building your own is entirely the *point* of the patent system – use one invention to lead to the creation of another.

  3. rfid says:

    Not quite as interesting as the WiFi gesture sensing but OK.

  4. Tracy Hall says:

    “Not quite as interesting as the WiFi gesture sensing…” ?!? This **is** WiFi gesture sensing – 2.4GHZ RF nodes….

  5. Alan says:

    Even if the detectors are great, the warning still needs to reach a human – and they need to respond.

  6. JBeale says:

    By the way you don’t need to do this at 2.4 GHz. The super-cheap baby monitor I got from Target, I believe in the 49 MHz band, has some distinctive interference noises that come and go depending on exactly where I’m standing. I assume related to various constructive / destructive inteference patterns at the 6 m wavelength it uses. I haven’t spent the time to investigate but seems like whatever is going on, could be used as a movement detector.

  7. cybergibbons says:

    I’ve been trying to get some samples to review, unfortunately Xandem aren’t obliging!

    Bertho – patents are very important for innovation. No point hiding them.

  8. CyberGibbons,

    We have no record of you requesting samples for review. I did offer to work out getting you a test system a while back, but you refused it due to lack of time. Just let me know if you have time now and we’ll figure something out.


    Matt Kankainen
    Xandem Technology

  9. Ronald Henderson says:

    Came upon this nice little article about TMD here

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