anaesthetica's Journal: Using a Cellphone As Your Guide to Japan

A new service, pioneered by three Japanese firms working in combination with a small American firm (GeoVector), allows Japanese cellphone users to gather point-and-click information about their surroundings. The technology uses satellite-based GPS, accurate within 30 feet, and an electronic compass linked to the internet. Firms in the United States currently cannot offer such a service, because U.S cellphone towers are accurate only to 100 yards, and only Verizon and SprintNextel offer GPS. From the article:

In addition to a built-in high-tech compass, the service requires pinpoint accuracy available in urban areas only when satellite-based G.P.S. is augmented with terrestrial radio. The new Japanese systems are routinely able to offer accuracy of better than 30 feet even in urban areas where tall buildings frequently obstruct a direct view of the satellites, Mr. Ellenby said. In trials in Tokyo, he said, he had seen accuracies as precise as six feet.