[time-nuts] FCC crackdown on GPS jammers
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Thu Feb 10 18:51:41 UTC 2011
John wrote:
>I had thought of building a very small one to jam the gps in my
>cellphone so AT&T couldn't tell where I was. But, I believe they use a
>time difference of arrival system. Verizon, on the other hand does use
>an embedded GPS for E911 purposes.
The carriers used to use triangulation from multiple cell towers to
determine position, but I thought the FCC required greater accuracy
and mandated GPS (either explicitly or practically) in the E911
rules. I could be mistaken. I think the GPS-based systems fall back
on triangulation if there is no GPS info from the handset, so the
carrier still knows where you are with reasonable accuracy most of the time.
Best regards,
Charles
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