Patent ID: 8188916

Claim:
A position/time detecting apparatus comprising: GPS reception means for receiving radio waves from GPS satellites and for acquiring information included in the radio waves; reception state detection means for detecting, from the received radio waves, (i) a number representing how many GPS satellites from which the radio waves were received, and (ii) respective intensities of the radio waves received from the GPS satellites; time period measuring means for measuring a time period; and position/time calculating means for calculating a current position and a current time of the position/time detecting apparatus based on the information acquired by the GPS reception means; wherein: in a first state in which the GPS reception means has received radio waves of a first quality value from a first predetermined number of GPS satellites within a first predetermined time period measured by the time measuring means, the GPS reception means acquires orbit information and time information from radio waves emitted by the respective GPS satellites, the time information indicating a GMT at the respective GPS satellite when the satellite emitted the radio waves; in a second state in which the GPS reception means has received radio waves of a second quality value smaller than the first quality value from a second predetermined number of GPS satellites smaller than the first predetermined number of GPS satellites within a second predetermined time period longer than the first predetermined time period measured by the time measuring means, the GPS reception means acquires time information from radio waves emitted by the respective GPS satellites, the time information indicating a GMT at the respective GPS satellite when the satellite emitted the radio waves; the position/time calculating means calculates in the first state the current position and current time of the position/time detecting apparatus based on the orbit information and the time information; and the position/time calculating means calculates in the second state the current time based on the time information.