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2019-03-07 09:09:11

Cellphone users can now be pinpointed with accuracy of a few metres. All networks can locate a handset to within a few hundred metres by seeing which base station it is using, and some cellphones have GPS signals that allow them to be located far more precisely. Now Qualcomm of San Diego has developed a system that doesn’t need GPS. All phones emit a timing signal, which nearby base stations retransmit. By measuring the time lag between signals,