Patent ID: 8140263

Claim:
A navigation apparatus for deriving a movement distance of a moving body on the basis of the number of pulses generated within a predetermined period accompanied with movement of the moving body and a conversion coefficient from the number of pulses to a movement distance, the navigation apparatus comprising: a detector configured to detect the number of pulses; a measuring unit configured to measure measurement data comprising at least a movement velocity and an accuracy reduction index on the basis of a signal received from a satellite, the measurement data measured every measurement timing; a first determining unit configured to determine validity of measurement data at each measurement timing on the basis of measurement data measured at the measuring unit; a second determining unit configured to determine whether to derive the conversion coefficient using the measurement data determined valid at the first determining unit; a deriving unit configured to derive the conversion coefficient on the basis of a movement velocity of the measurement data measured at the measuring unit and the number of pulses detected at the detector when the derivation is determined at the second determining unit, wherein the first determining unit reflects measurement data at a measurement timing that depends on a change of a period required for measuring the accuracy reduction index when determining validity of measurement data at a predetermined measurement timing; and a delay unit configured to control an output timing of the number of pulses from the detector to match with a measurement timing of measurement data at the measuring unit, the delay unit configured to output the number of controlled pulses to the deriving unit.