測場儀利用核磁共振（NMR）原理，使用邊緣振蕩器法對磁場進行測量。計量顯示
部分以CPLD 芯片EPM7128SLC84-6 和單片機OM4368BN 為核心部件，使用Verilog HDL
和C 語言設計頻率計，測頻范圍為1MHz~100MHz。通過對共振點處邊緣振蕩器的振蕩頻率進行測量，由單片機根據拉莫進動公式計算出磁感應強度，送液晶顯示器輸出。設計中引入了自動量程轉換，減少人工干預程度。
關鍵詞：磁感應強度；核磁共振；拉莫進動；頻率測量；自動量程轉換
Abstract: The device measures the magnetic field based on the theory of nuclear magnetic
resonance (NMR) and marginal oscillator. The measurement and display part of it takes
EPM7128SLC84-6 and OM4368BN as the core components. It uses Verilog HDL and C language to design a frequency meter, the range of which is from 1MHz to 100MHz. The device can measure the oscillator frequency when the resonance occurs, get the magnetic induction based on the Larmor precession formula, and display it by the Liquid Crystal Display (LCD).The device contains an automatic range changing technology, so it can reduce the degree of manual intervention.
Key words: Magnetic induction, NMR, Larmor precession, Frequency measurement,
Automatic range changing technology

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