RU7512U1 - DIGITAL FERROSENDER MAGNETOMETER - Google Patents

Description

Digital fluxgate magnetometer.

The utility model relates to magnetic measurements, in particular to fluxgate magnetometers.

Foreign and domestic devices of a similar purpose are known: a multiplex control circuit with a band-pass filter for a flux gate 1, a digital flux gate magnetometer 2. These magnetometers contain a flux gate with a compensation winding, an analog converter, threshold devices, an analog-to-digital converter, a digital source of a compensating field, and a computing unit.

A disadvantage of the known magnetometers is the low accuracy of the measurements due to the lack of calibration of the device.

The closest in technical essence to the claimed device is a digital flux-gate magnetometer 2. This device contains a flux-gate with a compensation winding, an analog transducer, a threshold element, a sign discriminator, a source of a compensating field, an analog-to-digital converter, and a computing unit.

The disadvantage of the prototype is that when the working conditions of the magnetometer change, for example, when the ambient temperature changes, the conversion coefficient of the main channel of the magnetometer (flux gate - analog converter - analog-to-digital converter) can change, which leads to an error in measuring the magnetic field strength.

The technical problem to be solved is to increase the measurement accuracy by calculating the conversion coefficient of the main channel of the magnetometer.

The problem is solved as follows. In a digital fluxgate magnetometer containing a fluxgate with a compensation winding connected to the first output of the compensating field source and to the input of an analog converter, the output of which is connected to the inputs of a threshold element, a sign discriminator and an analog-to-digital converter, the output of which is connected to the first input of the computing unit, the source of the reference field is introduced, and the computing unit is a controller made on the basis of a single-chip microcomputer. In this case, the second and third inputs of the controller are connected respectively to the outputs of the threshold element and the sign discriminator, and the first and second outputs of the controller are connected to the first input of the source of the compensating field and the input of the source of the reference field, the output of which is connected to the second input of the source of the compensating field.

Introduction to digital fluxgate magnetometer source and field measurements

  ,

execution of a controller based on a single-chip microcomputer allows the controller

by turning the source of the reference field on and off at the command of the user or periodically, determine the conversion coefficient and then, when calculating the magnetic field strength, take into account the change in the conversion coefficient.

M1SI G 01 R 33/02

A utility model is illustrated as follows. In FIG. The block diagram of a digital fluxgate magnetometer is shown.

A digital fluxgate magnetometer (see Fig.) Contains a series-connected fluxgate (1) with a compensation winding connected to the output of the compensating field source (5) and the input of the analog transducer (2), the output of which is simultaneously connected to the input of the threshold element (3), discriminator sign (4) and the input of the analog-to-digital converter (b), the digital output of the latter is connected to the first input of the controller (7), the second and third inputs of which are connected respectively to the outputs of the threshold element (3) and the sign discriminator (4), and the first and second outputs - to the first input of the source of the compensating field (5) and the input of the source of the reference field (8), the output of the latter is connected to the second input of the source of the compensating field (5).

Digital fluxgate magnetometer works as follows. The output voltage of the flux gate (1), containing the useful signal and the interference signal, is fed to the input of the analog converter (2), in which the useful signal is extracted as the second harmonic voltage of the excitation frequency of the flux gate (1) and then the signal is converted to DC voltage.

If the signal amplitude at the output of the analog converter (2) exceeds the threshold of the threshold element (3), then the controller (7), which analyzes the state of the outputs of the threshold element (3) and the sign discriminator (4), generates a code (NHKR) supplied to the source input compensating field (5), determined by the formulas:

(), (w) m + 1

if the signal sign at the output of the analog converter is positive

(ICP) i (ICP) i-l

if the sign of the signal at the output of the analog converter (2) is negative,

where i is the signal analysis cycle number;

(IKP) / - OD supplied by the controller (7) to the source register of the compensating field (5) in the previous signal analysis cycle at the output of the threshold element (3) and the sign discriminator (4).

The direction of the compensating field is determined by the sign of the number ()

As a result, a current is supplied from the output of the source of the compensating field (5) to the compensation winding, which creates a compensating field in the flux gate (1), the action of which leads to the fact that the signal at the output of the analog converter (2) is set within the specified limits.

Under this condition, the controller (7) receives the code of the number (Ni) from the output of the analog-to-digital converter (b) and, taking into account, as well as the signs NI and, performs calculations, the result of which corresponds to the magnetic field strength.

The controller (7) also determines the transfer coefficient (Kp) of the main channel of the magnetometer by turning on the source of the reference field (8), setting the signal (s) at its second output.

The signal from the output of the source of the reference field (8) is fed to the second input of the source of the compensating field (5), where it is summed with the compensation current supplied to the compensation winding of the flux gate (1).

Converter (2) a signal whose amplitude is approximately equal to half the threshold value of the threshold element (3).

We derive the formula by which the controller will determine the CD.

when (the source of the reference field (8) is off) we get:

ism p - ikp, (1)

where Nism is an external magnetic field;

NI is the signed number at the output of the analog-to-digital converter; N ICP is the signed number at the input of the compensating field source; Kpish - the coefficient of conversion of the source of compensating

Then it is established, as a result, the reference field (Ne) additionally acts on the flux gate (1), the direction of which coincides with the direction of the compensation field, so the controller (7) checks whether the signal at the output of the analog converter (2) exceeds the threshold of the threshold element (3) . Otherwise, the controller (7) sets at the input of the source of the compensating field (5) the number is one less and sets the discharge value again to get the NI and Kikp values. Thus, the controller (7) ensures that the number (N Ukp) is the input of the source of the compensating field (5) did not change at and.

As a result, when

± Ya + I Kjj -TV, + K -Nmn, (2)

where N is the signed number at the output of the analog-to-digital converter. As a result, on the basis of formulas (1) and (2) we obtain:

 This algorithm is only valid for measuring constant or slowly changing magnetic fields.

A prototype of a digital flux-gate magnetometer was made, in which the controller is based on a single-leaf K1830BE31 microcomputer.

Literature:

1.U.S. Patent No. 4677754, U1.O01KZZ / 02, 1984.

Multiplex control circuit with a bandpass filter for a ferrozop.

2.A.S. USSR No. 842657, class O01KZZ / 02, 1979, published in the Bulletin of inventions No. 24, 1981.

Claims (1)

A digital fluxgate magnetometer containing a fluxgate with a compensation winding connected to the first output of the compensating field source and to the input of an analog converter, the output of which is connected to the inputs of a threshold element, a sign discriminator, and an analog-to-digital converter, the digital output of which is connected to the first input of the computing unit, which differs the fact that the source of the reference field is additionally introduced, and the computing unit is a controller based on a single-chip microE M, the second and third inputs respectively connected to the controller outputs a threshold discriminator element and sign, and the first and second controller outputs connected to the first input of the compensating field source and the reference entry field source whose output is connected to a second input source of the compensating field.