APPARATUS FOR AUTOMATIC CALCULATION OF FOM

PURPOSE:To obtain apparatus requiring no manual work, by automatically confirming the flight azimuth and motion state of an airplane on the basis of the T-axis signal, L-axis signal and V-axis signal being the output signals of low sensitivity magnetometers and the differential values of said three signals to calculate 12 motion noises. CONSTITUTION:Low sensitivity magnetometers 11-13 respectively detect the magnitudes of the three-direction components, that is, the T-axis signal X, L-axis signal Y and V-axis signal Z of an external magnetic field (earth magnetism), in other words, the posture of a vehicle. A high sensitivity magnetometer 20 detects the change quantity of the external magnetic field. Subsequently, an A/D converter 30 inputs the outputs of the low sensitivity magnetometers 11-13, the outputs of differentiation circuits 11A-13A and the output of the high sensitivity magnetometer 20 to send analogue quantities to an operation circuit 40 as digital quantities. Then, the flight azimuth and motion state of an airplane are automatically confirmed in the circuit 40 and 12 motion noises are calculated to calculate FOM and the calculation result is displayed on a display circuit 50.