PURPOSE: To accurately detect the traveling azimuth of a vehicle, by correctly evaluating an abnormality, if any, in geomagnetism.
CONSTITUTION: An azimuth-detecting sensor 11 comprises an exciting winding 114 wound on a magnetic core 113 consisting of a ferromagnetic material and output windings 111, 112 wound on the core 113 orthogonally to each other. An oscillating circuit 181 outputs a rectangular wave signal S(181) for exciting at a frequency (f) through the winding 114. Outputs S(12), S(13) of a frequency 2f are obtained through filters 12, 13. The outputs S(12), S(13) are amplified by amplifying circuits 14, 15, and are subjected to sample holding at holding circuits 16, 17 by signals fed from a timing circuit 182, whereby azimuth detection signals (x), (y) are obtained at output terminals 161, 171, respectively. Based on the signals (x), (y) from an azimuth-detecting part 1 and a signal W from a steering angle detecting part 2, a calculating part 3 generates an azimuth signal.
KUNO AKIRA
NUMATA AKISHI
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