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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
