| 摘要 |
<p>PURPOSE:To perform measurement of high accuracy even by low power supply voltage by constituting an analogue amplifying circuit for amplifying a detection signal of two circuits, that is, a low gain amplifying circuit and a high gain amplifying circuit. CONSTITUTION:When a command is issued to a variable magnetic field measuring mode by an input key KEY, measurement is started by the order of a microcomputer CPV and an analogue amplifying circuit change-over SW is changed over to a low gain amplifying circuit LAC at first and an analogue signal is converted to a digital signal by an analogue/digital converter ADC and a value of a constant magnetic field is taken in a microcomputer CPU and a numerical value is stored and data is read in a low sensitivity state. When a negating magnetic field reaches + or -50nT or less, a variable magnetic field is measured and the measured value is recorded in an internal measuring apparatus and also outputted to an external recording device. In a variable magnetic field measuring mode, a measuring range is + or -300nT and converted by + or -15 bits and, therefore, even when lower figure two bits become uncertain, a resolving power of 0.05nT is sufficiently held and accuracy of 0.1nT is secured.</p> |
