SU805230A1 - Measuring device for geoelectrical survey - Google Patents

Description

The invention relates to electrical reconnaissance methods using established artificial electromagnetic fields, and can be used in methods of induced polarization (VP) and transient processes (MPP).

A device for geoelectrical exploration for measuring parameters of induced polarization is known. It contains receiving sensors, an amplifier, a discriminator of the signal level, a recorder, and a control device [1].

The device has low measurement accuracy and therefore cannot be widely used.

Also known is the measuring device of the INFAZ VP station, which has improved measurement accuracy, which contains an input receiving sensor, an amplifier, a driver, a time interval meter, a recorder, and a control device connected in series. The time interval meter contains an electronic key, a high-frequency quartz fill pulse generator, a pulse frequency divider, and counters [2].

However, the measurement results of this device are complicated by the action of pulsed interference affecting the operation of the Meter time intervals, and the measurement results accumulated in the counters may be distorted by an interference signal that violates the synchronization of the device.

The purpose of the invention is to improve the accuracy of measurement.

The goal is achieved in that in a device containing a sensor, an amplifier, connected in series, two signal level discriminators connected to the control inputs of which a control unit is connected, also connected to the input of a crystal oscillator, a two-input pulse counter connected to the outputs of the discriminators and loading two parallel-connected three-input matching circuits, the second inputs of which are connected to a crystal oscillator, and the third - to the outputs of one of the discriminators, as well as e device, in addition to the outputs of each coincidence circuit, two pulse shapers are connected in parallel, while the outputs of two shapers through single-input keys, and the other two through two-input keys, are connected to the calculating device.

In FIG. 1 shows a structural diagram of the proposed device; in FIG. 2 - time charts characterizing it (work.

the device contains a field pickup 1, a broadband amplifier 2, discriminators 3 and 4 of the signal level, designed to generate positive and negative polarity signals, a control unit 5, a crystal oscillator 6, which generates filling pulses, counter + 7 pulses, three-input circuits 8 and 9 coincidences that perform the functions of key elements in which the generated measured signals are filled with pulses of high repetition rate, formers of 10–13 counted pulses, one-input electronic keys 14 and 15, a two ^ input electronic key 16 and a digital computer 17.

the device operates as follows.

A generator (not shown in Fig. 1) excites the primary field in the form of pulses of positive and negative polarities. After the primary field is turned off by the receiving sensor 1, unsteady field pulses are observed (Fig. 2a and b). A positive or negative pulse signal (Fig. 2a and b) from the field sensor 1 is amplified by a broadband amplifier 2, the gain of which is regulated depending on the signal level: from the amplifier output, the signal is fed to the inputs of two discriminators 3 and 4, the response level of which is set by the operator with using the control unit. The signal has a falling trailing edge (Fig. 2a and b).

The discriminators are triggered after the pulse is turned off. Both discriminators return to their original position at the moment when the trailing edge of the signal is equal to the level of operation set by the operator. Thus, the measured signal by discriminators 3 and 4 is converted into rectangular pulses (Fig. 2 c), the duration of which is proportional to the signal amplitude set by the operator. To increase the accuracy and increase the noise immunity, measurements of the duration of converted pulses are performed not for one, but for several periods of the measured signal. To this end, with the exits ’. discriminators they are fed to the inputs of the counter 7 pulses. From the outputs of the counter 7 pulses a rectangular signal (Fig. 2d), with a duration proportional to the periods of the signals converted by discriminators 3 and 4, is fed to the first inputs of two three-input matching circuits 8 and '9. At the second input of the coincidence circuit 9, pre- formed from a positive signal (Fig. 2 a) by the discriminator 3, a rectangular signal (Fig. 2 c) is received, and at the second input of the coincidence circuit 8, a signal converted from the negative signal by the discriminator 4 The third inputs of the matching circuits from the output of the quartz oscillator 6 receive filling pulses (Fig. 26). From the output of the matching circuit 8, pulses (Fig. 2e) are fed to the inputs of the drivers 10 and 11, and from the output of the matching circuit 9 to the inputs of the drivers 12 and 13. The outputs of the drivers 11 and 12 are loaded on a two-input electronic key 16, and the outputs of the drivers 10 and 13 - respectively, to single-input electronic keys 14 and 15. The outputs of all three keys are fed to the input of a digital computer 17.

The signals from the matching circuits to the shapers 10-13 represent a sequence of pulses (Fig. 2e). Shapers 10 and 12 form rectangular signals corresponding to the leading edges of these pulses, and shapers 11 and 13 correspond to the trailing edges of these pulses. The pulses of the shapers 10 and 13 determine the signs of the signals (positive and negative), and the pulses of the shapers 11 and 12 determine their absolute value. Electronic keys 14 and 15 determine the nature of the mathematical operation of the processes performed in the digital calculating device 17. The digital calculating device performs the following operations: counting the number of filling pulses proportional to the level of amplitudes, measured by the operator, of the measured positive and negative signals; calculating the difference in the number of fill pulses proportional to the level of positive and negative measured signals set by the operator; implementation of other algorithms for processing and displaying information.

Thus, by setting different levels of amplitudes, measured both positive and negative signals with high accuracy, it is possible to determine the waveform of the established secondary fields observed during electrical exploration by transient and induced polarization methods.

Claims (2)

1. Chernov, G. Ya., Et al. On the instrumental method of measuring the temporal parameters of the induced polarization of geological media. Proceedings of VSEGINGEO, no. 90, 1975, p. 87 - 90. 2. A. Kulikov, E. Shemkin. A. Electrointelligence by the phase method of induced polarization. M., "Nedra, 1978. p. 82 (prototype). . LShLLSHTLShShLIIL