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Japan proposes 911 cellphone location system

Japan may soon have its own version of the American E911 system that pinpoints the location of a person making an emergency call. A report in the Japan daily Asahi Shimbun said that the Ministry of Public Management, Home Affairs, Posts and Telecommunications, the National Police Agency and three major mobile service providers are expected to test the system in 2005. Emergency call centers credit their ability to locate a landline phone with saving the lives of those unaware of where they are or too injured or panicked to provide any details.

However, unlike the proposed US system, which will depend on new technology to locate the phone, the Japanese cellphone tracking system will be based on the tried-and-tested GPS. GPS uses a network of satellites that beam identifying data down to earth. A GPS chip inside a car, boat or aircraft reads the signals from several satellites to calculate its exact location. GPS chips in mobile phones are an uncommon option at the moment, but prices are expected to come down and the Japanese authorities would make them a standard feature. In such a system, the phone user presses a button to send location coordinates to the emergency service provider, said the report. One drawback of GPS is that the device needs to have a clear view of the sky to read the satellites, so location tracking may be affected by being indoors or under cover.

As in the U.S. the majority of emergency calls in Japan now originate from mobile phones. Of close to 9 million calls the police received last year, just over half came from cellphones. In the U.S., wireless carriers have until 2004 to create a service that lets emergency call centers locate people who dial 911.

Carriers AT&T Wireless, Cingular and T-Mobile had originally chosen to use a technique called Enhanced Observed Time Difference (EOTD), which uses up to four cellular base stations to pinpoint a cell phone’s location by measuring the arrival times of the call at various cellular antennas. EOTD works well in cities, where cell phone antennas are plentiful, but in rural areas cellular antennas are sometimes miles apart. Instead of four base stations, often there are just two to help determine a location, which makes the measurement less accurate. The replacement technology, called Uplink Time Difference of Arrival (U-TDOA), determines a phone’s position by measuring the time a call reaches “location measuring units” inside a cell phone network base station. Carriers installing the technology, created by TruePosition, need only to add software into their networks. EOTD, on the other hand, requires software in a network plus specially made handsets. Cingular has already tested the U-TDOA system in Wilmington, Del., and the technology exceeded, in some cases, the FCC’s accuracy requirements, Cingular said.