Patent ID: 8065083

Claim:
An azimuth processing device connected to a storage and a compass sensor for outputting azimuth data based on measurement data output from the compass sensor, the device comprising: an accumulation section that stores pieces of the measurement data newly output from the compass sensor in the storage for accumulation of measurement data; an offset data calculating section that calculates an offset data candidate of the compass sensor based on plural pieces of the measurement stored in the storage; an offset data verifying section that verifies the offset data candidate by checking whether the calculated offset data candidate meets a predetermined criteria or not; and an offset data updating section coupled to the offset data calculating section, the offset data updating section updating offset data stored in the storage, wherein the offset data calculating section calculates the offset data candidate when a first predetermined number of pieces of the measurement data are stored in the storage by the accumulation section, wherein the offset data verifying section checks whether the calculated offset data candidate meets the predetermined criteria or not, wherein if the offset data candidate meets the predetermined criteria, the offset data updating section updates the offset data previously stored in the storage with the offset data candidate calculated by the offset data calculating section, and wherein if the offset data candidate does not meets the predetermined criteria, said accumulation section deletes a piece of the measurement data from the storage if the pieces of the measurement data stored in the storage reach a second predetermined number greater than the first predetermined number and stores a further piece of the measurement data output from the compass sensor, and otherwise said accumulation section stores a further piece of the measurement data output from the compass sensor without deleting the measurement data stored in the storage if the pieces of the measurement data stored in the storage do not reach the second predetermined number.