Patent US 8,090,535

An azimuth processing device is designed for outputting azimuth data based on measurement data sequentially output from a compass sensor. In the device, an accumulation section selectively accumulates substantially new pieces of the measurement data. An offset data updating section updates offset data of the compass sensor based on plural pieces of the measurement data accumulated by said accumulation section. An azimuth data output section outputs the azimuth data based on substantially newest measurement data and the offset data.