SU402838A1 - DEVICE FOR MEASURING MAGNETIC SUSTAINABILITY - Google Patents

Description

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The invention relates to the field of magnetic measurements and can be used to measure magnetic susceptibility for geophysical purposes, for the study of the physical properties of substances and in the municipal mining industry.

Devices for measuring magnetic sensitivity are known using resonant circuits, where the required value is judged by a change in frequency, phase or amplitude. At the same time, when any one parameter changes, the others also change. In phase devices with the same increments of reactance of the coil, the sensor of the phase increment and amplitude will be different depending on the amount of detuning of the circuit.

Amplitude limiters are commonly used to eliminate the effect of amplitude variation on the contour on the measurement results. In this case, the output voltage of the phase detector will be a function of the phase only. The magnetic susceptibility of the test substance is proportional to the relative change in the reactance of the coil-sensor, i.e. the detuning of the circuit. Due to the change in the phase transfer coefficient, depending on the magnitude of the detuning between (the readings of the phase detector and the magnetic susceptibility will be

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there is a linear dependence only in a limited range of detunings.

In the known devices for measuring the magnetic susceptibility by phase change on the oscillating circuit, amplitude limiters are used to maintain the voltage constant at the output of the phase detector, which complicate the equipment and distort the shape of the input signal.

To simplify the design and linear expansion of the measurement range, the proposed device is equipped with an amplitude divider, the input of which is connected to the output of the measuring circuit, and the output is connected to the second input of the phase detector, as a result of which the phase detector is applied without amplitude limiting It is both in amplitude and phase.

FIG. 1 shows the block diagram of the described device, where / is the master oscillator, 2 is the measuring loop, 3 is the amplitude divider, 4 is the phase shifter, 5 is the phase detector; 6 - indicator.

The master oscillator is assembled on quartz and generates highly stable oscillations of a given frequency, which are fed to a phase detector (a second one, and one phase input of the phase detector, the signal is fed through a phase shifter, and to the second through a measuring circuit and an amplitude divider. The inductance coil of the measuring circuit is The sensor is placed into which the test substance is placed. When the test substance is introduced into the roller sensor, the phase and the oscillation amplitude of the circuit change. Amplitude divider serves to change amplitude transmission coefficient in order to completely compensate for the change in phase coefficient transmission coefficient in order to obtain a linear dependence of the output voltage of the phase detector as a function of the detuning circuit. The phase shifter serves for an additional phase shift of the reference voltage so that in the absence of the test substance in the measuring coil, the signal at the output of the phase detector is zero. A phase detector with a measuring instrument serves to measure the phase shift between the supporting voltage coming from the master oscillator through the phase shifter and the voltage coming from the measuring circuit. The natural frequency of the resonant circuit is selected above the frequency of the master oscillator in the range of detuning O / C, 6.

The device works as follows.

In the initial state, the signal from the master oscillator is fed to one of the inputs of the phase detector through the phase shifter, and to the other through the measuring circuit and the amplitude divider, which determine the initial phase angle using the phase shifter so that the output signal of the phase detector was equal to 0.

When a test substance is placed in the measuring coil, a change in the phase n of the voltage amplitude on the oscillatory circuit occurs. This change is recorded by a phase detector, with the signal at the output of the device being directly proportional to the magnetic susceptibility.

FIG. Figure 2 shows the change in relative transmission ratios in the range of detuning from, 6 to K. .0 i.e. when the natural frequency of the resonant circuit is higher than the frequency of the supply voltage.

In this range, the relative gain in voltage decreases and in phase increases, and these dependences can be approximated by approximate straight lines. With the same slope of these lines and the initial detuning of the contour O, 6, an increase in the | transmitting coefficient in phase will be fully compensated by a decrease in

relative gain in amplitude, and the resulting change in the gain of the phase detector will be O, i.e. in a given detuning range (/ С -0,6-i-0)

the phase detuning detector will remain constant, and the output voltage of the phase detector will be a linear function of the detuning circuit, which is directly proportional to the magnetic susceptibility.

Thus, a suitably chosen divider, not a change in the phase of oscillations, weakens the relative gain over voltage by a factor of several times.

Subject invention

A device for measuring magnetic susceptibility, containing a quartz stabilized measuring oscillator; measuring; KOiHTyip, a phase shifter, a phase detector and an indicator, characterized in that, in order to simplify the design and extend the linear measuring range, it is equipped with an amplitude divider, the input of which is connected to the measuring output circuit, and the output is connected to the second input of the phase detector.

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