Intelligent frequency selection method for vector proton magnetometer

Abstract

Aiming at the problem that the measuring accuracy of a vector proton magnetometer is influenced since the signal strength differs when the vector proton magnetometer is used for measuring different components of a geomagnetic field and a frequency selection circuit has temperature drift change, the invention discloses an intelligent frequency selection method for a vector proton magnetometer, which can automatically adjust the amplification factor of a signal amplification circuit and the frequency selection characteristic of the frequency selection circuit. According to the method, frequencyselection and amplification are performed on a signal according to a frequency selection parameter and an amplification factor set by the vector proton magnetometer firstly, then the signal strength of the signal is measured, and the amplification factor of a frequency selection circuit is adjusted according to the strength of the signal, so that the signal strength is within a relatively appropriate strength range. Moreover, the frequency selection capacitance of the frequency selection circuit is finely adjusted, so that a next frequency selection signal is almost strongest, and the aims ofaccurate frequency selection and amplification are fulfilled. An implementation circuit consists of a frequency selection circuit, a signal amplification circuit, a signal filtering circuit, a signalstrength 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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