SU798667A1 - Geoelectrosurvey apparatus - Google Patents

Description

(54) DEVICE FOR GEOEPECTRIC SCIENCE

one

The invention relates to technical physics and can be used in geoelectromagnetic exploration by alternating electromagnetic fields, namely the methods of induced polarization (AC) on an alternating current.

There are known devices for measuring alternating current polarization with an alternating current, which contain a driving field (power amplifier (inverter) / master oscillator) and a radio receiver. station, receiving floor sensor, signal meter, receiving radio tl.

A disadvantage of the known device is that it does not allow directly measuring the polarization parameter of the medium, it must be calculated from the results of multi-frequency measurements, therefore, the accuracy of determining the EP parameter is low.

It is also known a device for measuring AC on an alternating current, containing a current circuit consisting of a generator connected in series, a power amplifier and a sensor of the field, as well as a measuring circuit consisting of a series receiving field sensor and a signal meter.

However, this device has a high error of direct measurements of the VP parameters due to a change in the amplitude and phase of the current in the driving field sensor, due to the flow of a constant component current in it. The introduction of radio stations to periodically monitor the magnitude of these changes does not allow for high measurement accuracy due to the fact that the changes in amplitude and phase are determined alternately at each frequency, and then the correction is calculated.

The purpose of the invention is to improve the measurement accuracy by eliminating the influence of the constant component of the current.

Claims (2)

The goal is achieved by the fact that a device, containing a current circuit consisting of a series-connected master oscillator, a power amplifier and a generator sensor, and a measuring circuit consisting of a connected receiving field sensor and a signal meter, have two two-position three-contact switches, common contacts which are connected to the output amplified-. L of power, normally closed contacts of each key are connected respectively to normally open contacts of another key and the inputs of the generator sensor field. The drawing shows a structural diagram of the proposed device. The device consists of series-connected master oscillator 1, power amplifier 2, the output terminals of which through two two-position three-contact switches 3 and 4 are connected by a generator sensor 5 as well as a receiving sensor 6 and a signal meter 7. The contacts of the on-off switches 3 and 4 are connected to the output of the amplifier 2 power, and the normally closed contacts of each of the keys 3 and 4 are connected respectively with the normally open contacts of the other key (4 and 3 respectively) and the inputs of the receiving sensor 5th floor. The device works in the following way. With the aid of master oscillator 1, signals of a given frequency or several frequencies (for example, 1.22 Hz and 3.66 Hz) are generated. As a master oscillator 1, a stabilized crystal oscillator and a oscillator with a frequency of 10-100 kHz are usually used, as well as a set of frequency dividers providing at their output signals of a given frequency. The output of master oscillator 1 is used to control power amplifier 2. As a power amplifier 2, an inverter is usually used in transistors or triacors, since, according to technical conditions, the voltage drop on semiconductor devices can vary from 0.5 to 1 V (sometimes up to 2 V), the output current of the amplifier 2, the power has a different amplitude during the positive and negative half periods. In addition, if the current form is not rectangular, but sinusoidal, and power amplifier 2 operates in class B or C mode, it is also impossible without a special selection of elements to obtain a strictly identical current amplitude of one and the other field. Under field conditions with significant changes in temperature, the ratio of the amplitude of current pulses of positive and negative polarity changes, as a result of which a constant component appears in the output current of power amplifier 2. The alternating current, together with the constant component, through the normally closed contacts of the keys 3 and 4 is fed to the driving field 5, for which the grounded line AB (electric dipole, cable of finite length or infinitely long cable) is used. Under the action of a constant component of the current flowing through the grounding electrodes of the sensor 5, electrochemical reactions take place, the impedance of the electrodes changes over time, as a result of which the initial phase and amplitude of the exciting alternating current also change, and the stronger the larger the constant value the current is flowing, and the longer this current flows through the electrodes, i the change in the initial phase and amplitude of the exciting alternating current causes the amplitude and phase of the receiving sensor 6 signal They change over time, according to an unknown law, and, consequently, the parameters of the measured signal meter 7 are determined not only by the polarizability and conductivity of the medium under study, but also by the change in the amplitude and phase of the exciting current. Over time, these changes increase, and the accuracy of measuring the parameters of the EP decreases. In the device, the three-contact switches 3 and 4 periodically switch from one position to the second, the normally closed contacts of the switch are opened, and the normally open contacts are closed. In this case, the direction of the constant component of the current flowing in the driving sensor field 5 is reversed; a reverse electrochemical reaction takes place on the screen from its electrodes. Irreversible reactions on the electrodes do not occur, therefore, over time there is no one-way changes in the amplitude and initial phase of exciting alternating current. Small changes in the amplitude and initial phase of the current for a period of time between the switching on of keys 3 and 4 have practically no effect on the accuracy of the measurements, since they are dependent. from the required accuracy of the units, the switching period of the keys 3 and 4 can be chosen by the operator sufficiently small (from several minutes to several seconds). Therefore, the signals measured by meter 7 carry only information on the polarizability and conductivity of the medium and are free from the effects of changes in the initial phase and amplitude of the exciting current. As a signal meter 7, a two-frequency phase meter device is typically used, tuned, for example, to 1.22 and 3.66 Hz. The invention The device for geoelectromagnetic, containing a current circuit consisting of a series-connected master oscillator, a power amplifier and a generator sensor, a measuring circuit consisting of a connected receiving sensor and a signal meter, which is characterized by the fact that by eliminating the influence of the constant component of the current, two two-position Frehkontaktnyh key, the common contacts of which are connected to the output of the power amplifier, normally closed to cycles, each key are respectively connected to normally open contacts of another key and generating vhodsshi sensor. Sources of information (Taken into account during the examination 1. Yu. V. Aladinsky et al. Equipment for phase measurements of AC on alternating current. Lime universities, Geologists and exploration, 1968, № 6, о. 155157. 2. Melnikov V. P., et al. Fundamentals of amplitude-phase measurements of the Yakut VP. Prince publishing house, 1974, Yakutsk, pp.119135 (prototype).