SU815689A1 - Magnetometer - Google Patents

Description

(54) MAGNETOMETER

  The invention relates to the measurement of the magnitudes and directions of the magnetic field strength vector in a flat coordinate system over a wide frequency range and can be used in geology, geophysics, magnetic measurement techniques, and other fields of science and technology. Instruments for measuring the magnitude and direction of the magnetic field vector are known, containing a magnetically modulated sensor with concentrators, where signal windings are wound, and concentrators are magnetically interconnected by means of a modulator on which its winding connected to the generator is located. The signal windings are connected to phase shifters through matching blocks and difference blocks, two adders and a phase detector with and a drawer 11 are included in the circuit. However, they are highly sensitive, the known devices have an increased error in determining the angular coordinates of the magnetic field vector. The aim of the invention is to improve the measurement accuracy. The goal is achieved by the fact that a magnetometer containing a non-reversible ferromagnetic modulator ring with excitation windings, two excitation generators, two power amplifiers, an amplifier, two synchronous detectors connected by inputs to the outputs of the amplifier and excitation generators, and outputs to the input of the adder, gauges phases and voltages, a series-connected subcarrier generator and a phase splitter are connected, two modulators connected to its output, connected to the excitation generators, whose outputs are connected respective windings vozbuzvdeni through power amplifiers, and inside the ring modulator placed neperemagnichivayuschees kopdo with two mutually perpendicular receiving windings coupled to the inputs of the amplifier. FIG. 1 shows the structure of a magneto-modulation input unit of a magnetometer; in fig. 2 - magnetometer block diagram. The magnetometer consists of an input magnetic modulation unit, in turn, consisting of an internal

a non-magnetized ring 1 on which two mutually perpendicular windings 2 and 3 of channel X and channel Y are placed, each consisting of two sections.

The inner ring 1 will be called receiving and windings 2 and 3, respectively, receiving. Outside the receiving ring 1 there is a ferrite modulator ring 4, on which two modulator windings are located. The winding of the 5 X-channel and the winding of the b-channel that are geometrically aligned and wound one to one. The inputs of the mr. Torus windings are connected to the outputs of amplifiers 7 and 8 ms. Y-channel and X-channel.

The inputs of the power amplifiers 7 and 8 are connected respectively to the outputs of the modulators 9 and 10, which in turn are connected to the generators 11 and 12 of the Y-channel and X-channel carrier frequencies. In addition, the second inputs of the modulators 9 and 10 are connected to the outputs of the phase splitter 13, the input of which in turn is connected to the output of the 14 pd-carrier generator. .

The receiving windings are connected to the inputs of each of the devices 15 and 16 with an amplitude by the co-ordination of the X-channel and the Y-channel. the outputs of the isolating devices 15 and 16 are connected to the inputs of the amplifier 17. The Baxojof amplifier 17 is connected to the inputs of the synchronous detectors 18 and 19 of the X channel and the Y channel, the second inputs of which are connected to the second outputs of the generator 11 and 12 of the carrier frequency. The outputs of the synchronous detectors 18 and 19 are connected to the inputs of the adder 20. One of the outputs of the adder 20 is connected to the amplitude indicator 21, and the second to the phase indicator 22, the second input (of which is connected to the second output of the 14th subcarrier generator.

Works magnetometer as follows.

The generator 12 of the X-channel carrier frequency generates a sinusoidal voltage with a frequency of Wx, the generator 11 of the Y-channel with a frequency of Wy. The subcarrier frequency generator 14 generates a sinusoidal voltage with a frequency of ft. In the phase splitter 13, this voltage is divided into two, which are out of phase by 90, i.e. The voltage of the form Un, sinfit is removed from one output of the phase shifter, and from the other the voltage of the DISCOS fit. These voltages are applied to modulators 9 and 10, to the inflow of the inputs of the modulators there are voltages from the outputs; carrier generators. Modulated voltages are removed from the TCF module outputs. On X-channel, modulator 10 is removed.

Ux U | sinAt-si,

the Y-channel from the modulator 9 is removed voltage

Uyi UiQcasnt sinwyt.

These voltages are fed to the inputs of the power amplifiers and from there to the windings 5 and 6 of the modulator. This leads to the fact that the change in permeability with time the inverse permeability of the modulator 4 5 will contain harmonics containing the composition with frequencies sinnt-sinw t and cosfXt coswyt. Because of the nonlinear characteristic of ferrite, the magnetic permeability spectrum n much more harmonics, however. they are not considered here (they will, since only two harmonics are distinguished by synchronous detectors. The remaining harmonics do not affect the operation of the magnetometer. 5 Thanks to magnetic modulation

outer ring, i.e. modulation of magnetic resistance, modulated and the flow of the measured magnetic field N. To simplify the calculations, we assume that the external magnetic field is constant in time. For low frequency magnetic fields, i.e. such, the frequencies of which are PCs (the results obtained for direct current are completely true5.

Let the vector of the external magnetic field H be directed at an angle b to the X axis, as shown in FIG. 1. Then the voltage removed from the output of the 2 X-channel NEC, relative to the working harmonics, will be

Lix HKWxCose- S i nnt- s i nW t + - + f HKWy cose-cosAi ..s i nWyt, (1)

similarly for channel Y from the output of the receiving winding 3 we get

U-iv NK In SW nt yu u) xtt

(S) + nk cJy sin B-HW-sin Oy t

where K is the proportionality coefficient.

Then, these signals are transmitted to decoupler devices 15 and 16, in which the amplitude transfer coefficient is dependent on the frequency in the operating frequency range of the 1 / tJ type. This is done in order to align the amplitudes of the harmonics with the frequencies and ijy. Since at the output of the 15 X channel decoupler, the output signal looks like

U2x n iCOb0bmnt sinu) nt - 5) HK cobe-coSfJt- iM cOyt,

at the output of the Y-channel isolation device

    nt-bin a)) t 4 / ,,

 ,

+ NC -, & 1m8 cosnt-siM uJyt.

Claims (1)

The amplifier 17 is a two-channel amplifier with absolutely identical channels in amplitude-phase characteristics, having a working frequency band with a uniform amplitude-phase characteristic, exceeding the frequency band of the sum of useful signals, i.e. all the useful harmonics in it are amplified strictly in the same way, without imposing additional different phase shifts for individual harmonics. The signals of the channels amplified to the required levels are fed to the inputs of synchronous detectors 18 and 19. For the X-channel detector, the reference input of which is connected to the 12-carrier X-channel a generator, the reference frequency is frequency (d) x, therefore at its output the voltage defined by the expression U3x 4K3, cos0.sinnt, 5/1 will be allocated at the output of the 19 Y-channel synchronous detector, the reference input of which is connected to the output of the generator 11 of the Y-channel at frequency tOyr respectively Ujx HKizbtMe COSQt (b) Voltages from the outputs of synchronous detectors arrive at the inputs of the summing device 20, in which the operation Uc U3xi-iu (l + c) is realized. (d) Thus, the voltage at the output of the summing cascade is a sinusoid with frequency,, the amplitude of which is proportional to the intensity measured in π and does not depend on the orientation of the field vector relative to the coordinate axes. The phase of the sinusoid is equal to the azimuthal angle of the vector of the magnetic field relative to the coordinate axes and does not depend on the magnitude of the field strength. From one of the outputs of the adder signal. enters the amplitude meter, the indicator of which is graduated in terms of the strength of the measured field. The second output of the adder is fed to the input of the phase indicator 22, the second input of which receives the voltage of the reference phase with a frequency from the generator 14 of the subcarrier. The output of the phase indicator is graduated in terms of the azimuth angle 6. Claim - to the input of the adder, phase meters and voltages, characterized in that, in order to improve the measurement accuracy, sequentially connected generator is introduced into it; the razors and a phase splitter connected to its output are two modulators connected to the excitation generators, the outputs of which are connected to the corresponding excitation windings through power amplifiers, and inside the modulator ring there is a non-reversible transceiver ring with two mutually perpendicular receiving windings connected to the inputs booster. Sources of information, fintoe in consideration when examining 1. USSR author's certificate № 545939, cl. G 01 R 33/00, 1976. 00 00 Wko31 Vmd2 7G Zb / lv U Lunge J ( 0 (f44zJ