Laser Surveillance Defeater

Imagine our chagrin when we first laid eyes on this “laser surveillance defeater.” It’s supposedly built to the security requirements of federal agencies. We don’t believe most government issue devices have exposed circuit boards or 9V batteries dangling from them. Laser surveillance works by bouncing the beam off of a room’s window. People speaking in the room cause the window to vibrate, which modulates the reflected laser beam. This device looks like it’s just a piezo buzzer meant to vibrate in vocal ranges. A quick search didn’t turn up any DIY projects, but it looks simple enough. Shomer-Tec would love you to purchase one for every window at $69 each. A small price to pay when you’re taking on people willing to spend $20.

[via Gizmodo]

13 thoughts on “Laser Surveillance Defeater

  1. This device is essentially useless.

    Their own promo says, “this device was engineered to defeat such filters by centering its frequency output at the middle of the human voice range…”

    By tuning it to a particular frequency, they’ve actually made it easier to filter out the noise it generates.

    Real “window buzzers” produce a spectrum of randomly varying frequencies that cover more than just the normal human vocal range (to cover harmonics, not just base frequencies).

    This might flummox amateurs who don’t know how to post-process audio to clean it up… but that’s about it.

  2. I’d rather have a few soundbites that repeat over and over, but with random intervals between bites.

    I’m not your friend, guy. I’m not your guy, buddy. I’m not your buddy, friend.

  3. You could just get a spotter scope and learn to read lips. Also, I wonder how well a laser microphone would work on a slightly diffuse surface, or through a screen? Angling the windows might also shoot the reflection out of range, and using a bubble window might spread the light too much to deal with at a considerable distance.

  4. @11

    Anything that diffuses light (like frosted glass or a screen) limits the effectiveness of a laser mic. The angling of the window idea could be effective. To pick up the reflected light, you usually have to have the laser and receiver perpendicular to the window and close to each other.

    Angling to window either up or down (i.e. making the reflected light return to a point well above or below the laser) could make it very difficult to pick it up as it’s a lot harder to move around vertically than horizontally to position the receiver.

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