| 摘要 |
PURPOSE:To obtain a compensation apparatus requiring no axial alignment of a compensation coil and three low sensitivity fluxmeter, by together using the analogue calculation part and digital calculation part of a compensation quantity calculation part to perform the calculation of compensation quantity. CONSTITUTION:Low sensitivity fluxmeters 11-13 for measuring the three-direction components Ex, Ey, Ez of earth magnetism, a high sensitivity magnetometer 20 for measuring the magnitude of an external magnetic field, a constant memory part 30, a compensation quantity calculation part 40 for performing the calculation of a noise magnetic field D according to a predetermined formula on the basis of the outputs from the fluxmeters 11-13 and the memory part 30 and a subtraction circuit 50 for subtracting the output of the calculation part 40 from that of the magnetometer 20 are provided to this compensation apparatus. The calculation part 40 is divided into an analogue calculation part 42 and a digital calculation part 42, and the analogue calculation part 42 operates quantity having a relatively large value among the three components and 3X3 constant matrices A, B of a permanent magnetic field Hp and quantity having a relatively small value is operated by the digital calculation part 41. By adding the outputs of two calculation parts, the noise magnetic field D is calculated and, by this constitution, compensation can be accurately performed within a wide range. |
