#179 – Greg Charvat Returns With A Book! – Laboratory Literature Laureate



Welcome back, Dr Greg Charvat! Greg was on the show about a year ago, talking about his startup, Butterfly Network and his MIT short course on the RADAR.

Thanks to Greg for being on the show again to talk about RF and authoring books. We can’t wait to have him back on to FINALLY tell us about Butterfly Network. Follow Greg on twitter at @MrVacuumTube.


  1. says

    The NSA LOUDAUDIO device is a common Knowles hearing aid microphone with an integrated audio amplifier. It pulse-position modulates a low frequency carrier signal, at say 100 kHz. This carrier signal then toggles the gate of a RF FET transistor which has (basically) antennas for the drain and source.

    When the devices is flooded with a remote RF CW carrier, at say 2 GHz, the RF carrier will become modulated (AM) with the room audio, which is received and mixed with part of the TX signal to leave the baseband signals.

    The video monitor device acts the same way, only it directly taps the red video line. You need to add the horizontal and vertical sync signals externally.

  2. says

    Interesting episode. I enjoyed the radar talk.

    fyi the spinning thing that is on top of the Google car (and was on our Urban challenge vehicle) is a Velodyne LIDAR ( http://velodynelidar.com/lidar/hdlproducts/hdl64e.aspx ) and not a radar. It has 64 lasers that returns over a million point per second for full 360degree coverage and very detailed point clouds (not as high as a Faro, but still pretty detailed).

    Coincidentally my blog post of the day was all about sensors http://kohanbash.com/sensor-modalities/

    Engineers also watch football (btw the last Steelers vs Browns game was pretty nice (Sorry Chris))

  3. Chris says

    So you can use your smartphone to look for car parks? Except you’re not allowed to use your phone while driving and you can’t park somewhere to use it without finding a carpark first…

  4. Chris says

    That ragemaster video sniffing thing, it’s a retro reflector that modulates the reflected signal with the video data in the VGA cable. So it’s not a tiny transmitter, its a modulating reflector. You then need your super expensive radar system to detect and decode the reflected signal.

  5. says

    Greg’s right about why military radios are destroyed. A radio is a piece of serialized kit. As a soldier, you could do serious jail time if you loose one.

  6. rasz_pl says

    Butterfly Network is a cover for NSA TOC R&D operation. 3 years running and no official product, yeah right :)

  7. chexclaim says

    Chris, I think you should go on shortwave as Greg suggested. You can set up a poll to see the possible audience!

    • says

      Yeah, lots of religious programming, but that’s who pays to be on shortwave. I have a call in to them to see if we can’t interject some irreverence 😉

      • says

        Ha, just saw that you’d posted the flickr stream on Reddit three days ago… I’m behind.

        It would be pretty sweet to actually hear you guys on the air (almost in my backyard!) and I’m hopeful they’re nerds enough to work out a deal. I guess it’s time to rehab at least one of my stack of half-working shortwave receivers…

  8. says

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