Intelligent frequency selection method for vector proton magnetometer

Abstract

When the vector proton magnetometer measures different components of the geomagnetic field, the signal strength will be different, and at the same time, the frequency selection circuit will have temperature drift changes, which will affect the measurement accuracy of the instrument. To solve these problems, the present invention has invented an automatic adjustment The method of intelligent frequency selection of the vector proton magnetometer based on the amplification factor of the signal amplification circuit and the frequency selection characteristics of the frequency selection circuit. This method first selects and amplifies the signal according to the frequency selection parameters and amplification factors set by the instrument, and then measures the signal. According to the strength of the signal, adjust the magnification of the frequency selection circuit to make the signal strength in a more suitable strength range, and fine-tune the frequency selection capacitance of the frequency selection circuit to make the next frequency selection signal close to the strongest and achieve accurate selection. frequency and amplification purposes. The realization circuit of the present invention is composed of four parts: a frequency selection circuit, a signal amplification circuit, a signal filter circuit, a signal strength detection circuit and a single-chip microcomputer control circuit.

Description

[0001] Technical field [0002] The invention relates to a frequency selection method for measuring the intensity of the earth's magnetic field in a proton precession mode, in particular to a frequency selection method for measuring vector proton precession signals in an intelligent way for multi-component measurement. [0003] technical background [0004] The proton magnetometer measures the geomagnetic field by using the principle of proton precession. The proton precession signal is a frequency signal. After frequency selective amplification and filtering, it becomes a square wave frequency signal. After measuring the frequency of the signal, then The value of the geomagnetic field is obtained by multiplying it by a coefficient. After the proton magnetometer is equipped with a multi-component coil, it becomes a vector proton magnetometer that can measure multiple components of the geomagnetic field. When the vector proton magnetometer measures multiple components of the geo...

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Problems solved by technology

When the vector proton magnetometer measures multiple components of the geomagnetic field, the frequency selection and amplification of the signal are usually the same circuit, but the signal strength and frequency selection characteristics are different; in terms of signal strength, the total geomagnetic field strength The proton precession signal is stronger, and the proton precession signal of the component is weaker. If the signal amplification factor of the vector proton magnetometer is designed with the weak signal component, the signal amplification factor for measuring the total field strength will be higher than the required amplification factor. If it is much larger, it will affect the signal-to-noise ratio of the total field strength, thereby affecting the precision of the total field strength measurement, otherwise it will affect the signal-to-noise ratio of the component, thereby affecting the precision of the component measurement; as far as the frequency selection characteristics are concerned, the instrument When the resonant frequency of the frequency-selective circuit is consistent with the frequency of the proton precession signal, the signal obtained by the frequency-selective circuit is the strongest. Due to the influence of the frequency-selective capacitor and probe inductance, the temperature will change. When the vector proton magnetometer measures each component , may not always work in the best resonant frequency selection state, which will affect the frequency selection characteristics of the instrument, weaken the signal obtained by the instrument, and thus affect the measurement precision of the instrument

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