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    Re: GPS jamming concerns
    From: Frank Reed
    Date: 2016 Aug 8, 13:40 -0700

    Todd Humphreys has made quite a cottage industry of GPS jamming and spoofing hype. He even got his photo in this article... Not bad! But that doesn't quite match up to the level of techno-fame associated with a TED Talk: watch the video Todd Humphreys: How to Fool a GPS.

    The article talks about super-criminals jamming GPS for a mile or two around their operations. So... then... if we want to catch super-criminals, all we have to do is look for mile-wide holes in GPS coverage?? Right?! Given the ubiquitous use of GPS in smartphones (99% of all GPS chipsets are in smartphones), it should be relatively simple to detect this sort of jamming with some sort of crowd-sourced solution. Google already tracks tens of millions of GPS user positions, live and continuously, for its traffic applications. Holes in the coverage bigger than a few hundred meters should show up instantly. Highly localized jamming in areas smaller than, let's say, 10 meters radius would be much more difficult but still possible to detect. We will never be free of one-off assaults, like holding a major port hostage by jamming GPS as part of an extortion scheme, or jamming GPS in a military attack, but casual jamming on any scale larger than a hundred meters should be a short-term nuisance, eliminated by the high value of the very technology it seeks to circumvent.

    Myself, I use GPS while driving almost every day primarily because of the huge value of traffic-routing, but also for the sheer pleasure of driving tourism. It has never been easier to visit new places and to try new routes to familiar places. I would say I have been using a GPS mapping solution like this every day for about five years (about an hour per day on average, amounting to a sample of over 1500 hours --not a huge sample, but not insignificant). I have never seen any GPS jamming "holes". There are plenty of cellular coverage gaps where map data disappears, but no GPS signal gaps, yet. My phone GPS did go down repeatedly for a while about a year and a half ago. I suspected all sorts of things on our list of suspects including jamming, solar flares, and military attacks on satellites. Turns out the backplate on the phone was loose and it was allowing the GPS antenna to lose electrical contact (so goes the Internet theory). A little twisting with a tiny screwdriver fixed it --a strangely low-tech solution to a high-tech problem.

    Frank Reed

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