SU989506A1 - Digital magnetic variation converter - Google Patents

Description

This invention relates to geophysical prospecting using the earth's magnetic field (EMF). Instruments for investigating variations in EMFs are known - magnetostatic variometers containing a magnet with a mirror suspended on quartz extensions, an illuminator, an amplifier, a feedback cutter, an analog-to-digital converter 1. The well-known instruments have insufficient accuracy. Also known is a digital converter of variations in the geomagnetic field, containing a magnetically sensitive variometer with a phototransducer and a coil of the reverse magnet. zi, a clock pulse generator with a counting driver and a pulse counter, a reference current source with a current switch. The principle of operation of the analog-digital converter is based on the formation of a digital readout of the EMF variation at the time of equality of the measured field and a given one, which is fixed by the phototransducer 2. A disadvantage of the known device is the low noise immunity from impulse noise, industrial interference when they coincide with the moment of the digital readout. The purpose of the invention is to increase the noise immunity by reducing the influence of industrial frequency interference and pulse interference on the conversion result. This goal is achieved by the fact that a digital magneto-variational converter containing a magnetically sensitive varismeter with a phototransducer and a feedback coil, a clock generator, a counting driver, a pulse counter, a reference current source and a switch of the stream, additionally contains a current amplifier, a capacitor, a comparator, a clocking device, a compensation coil and a synchronization circuit, while the output of the photoconverter is connected to the input of a current amplifier, the output of which is through a condenser the sator is connected to the feedback coil and connected via a comparator to the first input of a clock device, the second input of which is connected to the output of the clock generator, the first output of the clock device is connected to the counting input of a pulse counter, the gate input of which

The counting time generator is connected to the clock pulse output of the reference current source output through a current switch controlled by signals from the second clock output, connected to a power coil, and a clock change output is connected to clock clock and counting clock inputs.

The drawing shows the functional diagram of the device.

Digital magnetobaria converter contains magnetically sensitive variometer 1 with photoconductor 2 and feedback coil 3 connected through a capacitor 4 to the output of current amplifier 5, the input of which is connected to the output of photoconverter 2, to the output of current amplifier 5 through a cah / .parator 6 the first input is connected a clock device 7, the second output of which is connected to the control input of a current switch 8 connected between the output of the reference current source 9 and the compensation coil 10 of a magnetically sensitive variometer a 1, the second input of the clock device 7 is connected with the output of the clock pulse generator 11, and the first output is connected with the counting input of the counter 12, the gate input of which through the counting time generator 13 is connected with the clock pulse generator output 11, clock inputs of the clock generator 11 and the counting clock 13 are connected to the output of the synchronization circuit 14.

The device works as follows.

Under the effect of variation, the magnet of the variometer 1 rotates to a certain angle, which causes a proportional change in the current of the photovoltaic converter 2, which is amplified by the current amplifier 5 and fed through the capacitor 4 to the feedback coil 3. The induction of the magnetic field in the feedback coil is equal in magnitude and oppositely directed induction t magnetic field variation. The current flowing through the feedback coil 3 charges the capacitor 4. The voltage across the capacitor 4 is proportional to the average value of the magnetic field induction during the integration time. When the voltage on the capacitor 4 reaches the threshold value of the comparator 6, the potential from the output of the comparator 6 is fed to the first input of the clock device 7, to the synchronization input of which the clock pulses of the generator 11 are received, by which the clock device 7 is transferred to the state where 8 to the compensation coil and

10, a reference current source 9 is connected during one clock frequency period. The current of the source of the reference current 9 creates in the volume of the magnetically sensitive variometer 1 a magnetic field directed opposite to the measured field, as a result, the magnitude of the current of the feedback coil 3 changes, the voltage across the capacitor

4 is reduced to a value less than the threshold value of the comparator 6. After the end of the reference current pulse, the amount of current feedback determines the time interval during which the clock pulses do not pass through the clock device 7. The steady-state process of charge-discharge of the capacitor 4 is repeated; at the output of the clock device 7, a sequence of pulses is formed, which is fed to the input of the pulse counter 12 during the counting time, specified by the counting time generator 13. The error is the voltage is determined by the instability of the reference current source 9 and the errors associated with the compensation coil 10. The synchronization circuit 14 performs the reciprocal synchronization of the frequency of the clock generator

11 with a mains frequency to eliminate the effect of industrial frequency interference by integrating it.

The proposed device makes it possible to increase the noise immunity of the conversion by eliminating the influence of the parameters of the converter elements, the instability of the frequency of the clock generator. The device is most effective in processing variations of the MPZ averaged over a period of 1-2.5 minutes.

Claims (2)

Formula invented A digital magneto-variating converter containing a magnetically sensitive variometer with a photovoltage converter and feedback coil, a clock generator, a counting driver, a pulse counter, a reference current source and a current switch, distinguish that, in order to increase noise immunity, it additionally contains a current amplifier, a capacitor, a comparator, a clocking device, a compensation coil, and a synchronization circuit; the output of the photoconverter is connected to the input of the current amplifier, you the stroke of which is connected to the feedback coil via a capacitor and connected to the first input of a clock device through a comparator, the second input of which is connected to the clock pulse output, the first clock output (and its connecting device to the counter input of the pulse counter, strobments, the input is coprogable through the time generator the counting is connected to the generator with the output of clock pulleys, the output of the reference current source is through a current switch, packaged by signals from the second output, and a clock device, It is connected with the coil ksn4pensation, the output of the synchronization circuit is connected to the clock synchronization clock inputs. “The Moule and Former of Time References Information Sources Accepted by Expert Assessment I. Afanasyev Yu.Z., N. N. Studentsov. Tselkin A.P. Magnetometric devices, converters, installations. L., Airgia, 1972, p. 18. , 2. USSR author's certificate 575bb3 c. 01 V 3 / pp, G01J 1/00, 1977 (prototype).