White House wants plans for GPS shutdown
Global Positioning System
would be disabled during crisis
to keep enemies from using it
This is an interesting story, but the means for jamming any GPS locally already exists. We accidentally discovered it at work, investigating a customer complaint that their laptop caused their Magellan GPS to quit working. It was the clocking of the CPU, at 1.2 GHz that did it. The laptop case pretty well blocked most of the interfering signal, but some escaped out of the fan vents. After some testing, we found that no GPS worked within 10 feet line of sight of the fan vents. We watched the power meters on the GPS satellite signals drop to zero when we aimed the vents at it.
Since the CPU clock is a very weak signal, it was my guess that this shutdown feature had already been built into the GPS chip or that the satellite signals were also in that range. Since 12 feet, the normal resolution of a GPS pinpointed location, is close enough for a lot of nastiness, it was my guess that this backdoor shutdown was a deliberate security feature. You can use your imagination on what the GPS might do on, say a UPS truck, when it got in range of its predetermined, uh, destination, but specific locations could still be secured by local jamming once a threat manifested itself.
9:39:11 PM 
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