SU811160A1 - Survey apparatus - Google Patents

Description

yykom reference signal connected to the control unit.

Such a structural embodiment of the device makes it possible to monitor changes in the sensitivity of the device and automatically keep it constant when the external and internal conditions of operation of the device change.

The drawing shows a block diagram of the device.

The device comprises a generator sensor 1 field, a current generator 2, a current regulator 3, a control unit 4, a reference signal source 5, a matching unit 6, an auxiliary receiving sensor 7, a main receiving sensor 8, a signal meter 9.

The device works as follows.

Using an oscillating sensor 1 connected to a current generator 2, an alternating electromagnetic field is excited in the medium under study. As a generator sensor 1, an induction frame, a loop, a grounded dipole, a grounded supply line up to several kilometers long can be used. As a current generator 2 to be used any commercially available generator.

At the specified test points, there is a main receiving sensor 8 connected to a signal meter 9. As a receiving sensor 8, an inductive transducer can be used (when measuring magnetic fields), a toroidal non-contact electric field sensor (when measuring vortex electric fields) or a grounded dipole (at measuring potential electric fields). As a signal meter 9, commercially available apparatus for measuring amplitudes and phase differences can be used.

Let a grounded supply line with a length of 1-2 km, located on the surface of the earth be used as a generator sensor 1, and a horizontal induction transducer is used as a receiving sensor 8. The total magnetic field at the measurement point Contains three components: one vertical, mainly determined by the normal field excited by sensor 1 in the air (this component is almost independent of the properties of the earth), and the bottom horizontal, which can be chosen so that to be determined only by the secondary field (such a component depends mainly on the properties of the earth and is useful, carrying the necessary information).

At the measurement point, in addition to the sensor 8 (horizontal), a sensor 7 (vertical) is located, the construction of which completely repeats the design of sensor 8. At the sensor 7, through matching unit 6, is connected to control unit 4. Matching unit 6 is designed to optimally match the output parameters of sensor 7 with control 4. The control unit 4 can be made in the form of a comparison circuit on two inputs and a power amplifier. The output of the matching unit 6 is connected to one of the inputs of the comparison circuit, and the source output is connected to the other input.

signal 5. At the two inputs of the control unit

4 will be affected by two voltages

one from signal source 5 and the other -

from the output of the detector block matching 6.

If the magnitude of these voltages is different,

then the error signal appears at the output of the comparison circuit of the block 4, this signal is amplified by the power amplifier and from the output of the control block 4 goes to the current regulator 3. The current regulator 3 changes the current generated by the generator 2 so that the output voltage of the matching block 6 became equal to the voltage source of the reference signal 5. As current regulator 3 can be used

a control transistor, a phase-controlled trinistor, a pulse-width modulator, and other standard circuits of electronic current regulators.

Thus, signal changes by

The output of the sensor 7 field is automatically compensated by changes in the magnitude of the current exciting the sensor 1. Due to this, at the operating frequency, regardless of changes in environmental conditions, the sensitivity of the device (output signal of sensor 7, as well as sensor 8) will be maintained with a given accuracy, and changes in the signal at the output of sensor 8 will be determined only by the properties of the studied medium (earth).

In operation with a sinusoidal current, the signal source 5 is implemented as a block of an amplitude-stabilized sinusoidal voltage, the input of which is connected to the auxiliary output of the current generator 2 (not shown) to obtain a coherent reference signal.

In a number of cases, for example, when measuring

vortex electric fields, field sensors 7 and 8, due to insufficiently wide bandwidth, differentiate the input signal (or, due to the polarization phenomenon of the surrounding medium, integrate it), which

also leads to a change in the sensitivity of the device at different frequencies. If, for example, the shape of the current produced by the generator 2 is rectangular, then the signal at the output of sensor 8 has

which the greater, the lower the frequency. To eliminate this, sensor 7 has a floor near generator generator 2. In this case, the useful signal received by sensor 8 is not present in the signal

sensor output 7.

As in the first of the cases described above, the current regulator 3 during each pulse changes the current produced by generator 2 so that the voltage form at the output of sensor 7 is kept rectangular, and at the output of sensor 8 differs from rectangular only nor the earth (the medium under study), and these deviations serve to characterize the properties of the medium under study.

Claims (2)

1. Superconductivity in geoelectromagnetic, ed. V.S. Surkov, “Nedra, Novosibirsk, 1977, p. 125-129. 2. USSR author's certificate No. 523524, cl. G 01R 33/02, 1976 (prototype).