Portable terminal device

摘要

A portable terminal device including GPS correctly detects a position thereof by preventing an error due to a state of an environment thereof. In a portable telephone including a GPS receiver capable of receiving a GPS signal according to GPS assist information sent from a reference GPS receiver server continuously receiving GPS signals from GPS satellites, a result of acquisition of each GPS signal received by the telephone using the GPS assist information and the like is evaluated to produce GPS information to be reported to the server.