SU118562A1 - Device for frequency electromagnetic sounding for electrical mineral exploration - Google Patents

Description

For frequency electromagnetic sounding, electrical exploration of minerals uses devices that separately fix the electric and magnetic components of the electromagnetic field arising in the earth and contain a generator with a supply dipole and a receiving station with electrodes and a horizontal loop.

The proposed device is more perfect, since it provides an increase in noise immunity, especially at infra-low frequencies.

This is achieved by the fact that a drum for magnetic recording of measured voltages and a synchronizing disk, generating a generator turn on signal and ensuring the recording of these voltages during one revolution of the drum, as well as reproduction amplifiers that connect to sound pickup heads at one fixed speed of rotation of the drum.

The proposed device (see diagram) consists of a generator with a supply dipole and a receiving station with electrodes and a horizontal loop.

The receiving station contains a magnetic drum (for recording measured voltages) and a synchronizing disk 2, which generates signals that control the switching on of the generator, and record the measured voltages during one revolution of the drum.

The magnetic drum / and synchronizing disk 2 is driven in rotation from synchronous motor 3 via multi-speed reduction gear 4. Power to synchronous motor 3 is supplied from power supply unit 5.

The synchronizing disk 2 has around the circumference a number of evenly spaced cuts, made in such a way that their width is equal to the distance between adjacent cuts (the width of the tooth).

No. 118562

When the disk rotates at the moment of passing the next slot between the lamp 6 and the photocell 7, a beam of light falls on the latter, causing a current pulse in its circuit. This pulse is transmitted through a special modulator 8 and radio station 9 to the generator, causing a pulse to be sent to the supply dipole.

The generator current creates in the earth an electromagnet field, the electrical part of which is perceived by the receiving electrodes, and the magnetic field by the horizontally flying loop of the receiving station.

The electric and magnetic components of the electromagnetic field created in the earth after amplification by amplifiers 10 and 1 are recorded on a magnetic drum.

The frequency of the current sent by the generator to the ground is determined by the number of slots on disk 2 and its speed of rotation. With this speed, it is possible to vary the operating frequency over a wide range.

In addition to a series of slots for controlling the generator, there is a narrow slot on the disk 2 located on a circle of smaller radius. This slit is intended to control the electronic switch 12, which is a trigger device with two functional states. At the moment of passage of a slit in the disk 2 between the lamp 13 and the photocell 14, the flow of light causes a current pulse in the photocell circuit and throws the electronic switch 12 to another stable state. In this case, the switch 12 gives a pulse to turn on the amplifiers 10 and 11.

After the sync disk and the magnetic drum / make one full turn, the slot in the disk .2 is again between the lamp 13 and the photocell 14. In this case, the photocell current pulse throws the electronic switch 12 into the initial state, in which the amplifiers 10 and 11 will be locked, eliminating the possibility of re-recording on the drum.

At the end of the recording, the gearbox switches to a certain constant rotational speed, independent of the operating frequency, and the recording starts to play.

The converted signals pass through selective reproduction amplifiers 15 and 16 and are fed to lamp voltmeters / 7 and phase meters 18 of the respective channels.

The reference voltage to the phase meters is taken from the modulator 8. The phase shift between the reference voltage and the measured signals is determined by the phase shift between the pulses recorded on the magnetic drum and the corresponding teeth and slots of the synchronization disk. This phase shift, in turn, is equal to the sum of the phase shifts in the earth and the individual nodes of the equipment.

The instrumental phase shifts are determined by the direct operation of the generator at the input of the receiving station, when phase shifts in the ground are excluded, and are subsequently subtracted from the readings of the phase meters.

Subject invention

A device for frequency electromagnetic sounding during electrical exploration of minerals, fixing separately the electric and magnetic components of an electromagnetic field arising in the earth, containing a generator with a supply dipole in a receiving station with electrodes and a horizontal loop, characterized in that, in order to increase the noise immunity, especially low frequencies, at the receiving station, a reel driven for magnetic