RU2671299C9 - Method and device for measuring parameters of underlying environment - Google Patents

Abstract

FIELD: measuring equipment.SUBSTANCE: invention relates to measuring equipment and can be used to measure the parameters of the underlying environment in radio communication systems for selecting the location of the transceiver equipment. Essence: measurements of the parameters of the underlying medium are made using probes, placed in the underlying environment with a serial circuit connected to the probes from the reference capacitance and a contact device controlled by a digital computer. In this case, the measurement of absolute permittivity εis performed in the following sequence: measure the oscillator frequency ƒwith an open contact device, measure the generator frequency ƒwith a closed contact device with the connection of the reference capacitance C, εis determined by calculation according to formula ε= εε = C/A, whereA – constructive parameter. Specific electrical conductivity σ of the underlaying environment is calculated by formula σ = ƒ⋅ε/π.EFFECT: technical result: increase in the accuracy of measurement of electrophysical parameters and expansion of functional possibilities.4 cl, 4 dwg

Description

The method of measuring the parameters of the underlying medium and a device for its implementation relates to measuring technique and can be used in radio communication systems to select the location of the transceiver equipment.

Radiation and reception of radio signals is carried out through antennas, the effectiveness of which depends on the electrophysical parameters of the underlying medium. Known methods for evaluating the emitted radio signal according to the electrophysical characteristics of the underlying environment for a certain area of location (see, for example, Japanese patent JP No. 4376071, H04B 3/46 "Method for measuring emitted radio waves").

Known methods are based on the use of an antenna as a primary sensor, a device for converting the parameters of the underlying medium, an analog signal to digital converter, a digital computing device and a storage and display device.

Analog methods are based on the determination of the electrophysical parameters of the underlying medium by measuring the loss of electromagnetic energy in the underlying medium. Losses are defined as the integral of the product of the surface impedance of the underlying medium and the square of the current density. This method gives fairly accurate results when the field strength of the underlying medium varies slightly along this surface at a distance of the order of the depth of the skin effect.

However, if this condition is not fulfilled, then the field strength in the underlying medium cannot be adequately determined through the normal component of the electromagnetic wave propagating along the earth's surface. In this case, the emissivity of the antenna located near the underlying medium changes, which is a disadvantage of analogues.

The characteristics of the antenna elements, when they are surrounded by the material environment, are very different from their characteristics in the air, due to the influence of the electrical properties of the material of the medium and even its shape and size, if the influence of the material medium is not very strong.

To assess the emitting ability of the antenna from the electrophysical parameters of the underlying medium, devices containing a periodic signal generator, a measuring antenna, an antenna input impedance meter, an analog-to-digital converter, a device for mathematically processing the received data and displaying the measurement results, a source of a periodic test signal, take the input impedance antenna above the underlying medium from the frequency of the source of the periodic signal (King ., G. Smith Antennas in material media, Vol 1 - M:. World 1984, RU 209846 ,. RU 2188439, US 5175500).

In this case, the actual component of the surface impedance of the medium is measured. The emissivity of the antenna depends on the impedance of the medium, represented as the sum of the real and imaginary components. To evaluate the imaginary component, additional measurements are made. Moreover, additional equipment is used for these purposes, which makes the measurement process more expensive and reduces its accuracy and objectivity.

The closest analogue in technical essence to the proposed one is the method described in RF patent No. 2316113, Н04В 3/46 “Method for measuring the parameters of the underlying medium and a device for its implementation”, adopted as a prototype.

The prototype method consists in using a loop antenna, in the center of which there is a Hall sensor powered by a generator, the frequency of which is selected in the range 2 ... 200⋅ (σ⋅S) ^-1 ⋅10 ⁴ , where σ is the conductivity of the underlying medium (S / m ), S is the area of the loop antenna (m ² ), determining the phase shift between the input current and the output voltage of the Hall sensor F (rad), which determines the conductivity of the underlying medium by the formula: σ = 0.66⋅10 ⁶ ⋅ (Ф-0 , 2) ² / (f⋅S).

The prototype method is based on the dependence of the magnetic field on the parameters of the underlying medium. It is known that, depending on the parameters of the material medium, the magnitude of the magnetic field changes, but this dependence is much less dependent on the presence or absence of moisture (and water) in the underlying surface and the polarization of the electrodes, since there are no unidirectional motion of electric charges in these measurements.

The description of the proposed method and device for its implementation is illustrated by graphic materials. In FIG. 1 shows a diagram of a prototype device; in FIG. 2 - diagram of the proposed device; in FIG. 3 is a diagram of a generator; in FIG. 4 shows the dependence of the frequency of the generator on the relative dielectric constant of the underlying medium.

The closest in technical essence to the proposed is the device described in the patent of the Russian Federation No. 2316113, HB04 3/46, adopted as a prototype.

The circuit of the prototype device is shown in FIG. 1, where indicated:

1 - loop antenna;

2 - generator;

4 - computing device;

5 - display and memory device;

8 - feedback resistor;

9 - operational amplifier;

10 - phase-sensitive bridge;

11 - Hall sensor.

The prototype device contains a series-connected generator 2 and an operational amplifier 9, the non-inverting input of which is connected to the midpoint of the feedback resistor 8, and the output of the operational amplifier 9 is connected to the first terminal of the frame antenna 1.1, the second terminal of which is connected to the first current output of the Hall sensor 11, the first and second voltage leads of which are connected to the third and fourth inputs of the phase-sensitive bridge 10, respectively, the first input of which is connected to the output of the generator 2, the second input to the point Connections one terminal of the feedback resistor 8 and the common bus. Another output of the feedback resistor 8 is connected to the second current output of the Hall sensor 11. The output of the phase-sensitive bridge 10 is connected to the input of the computing device 4, the output of which is connected to the input of the indicating and storage device 5.

An option for constructing a phase-sensitive bridge 10 scheme can be the scheme presented to the book Buchholz V.P., Tisevich E.G. Capacitive converters in automatic control and management systems. - M: Energy, 1972.P. 48.

The device for measuring the parameters of the underlying environment as follows.

When the generator 2 is turned on, its output signal is supplied to the first input of the phase-sensitive bridge 10 and to the inverting input of the operational amplifier 9, covered by current feedback, the signal of which is removed from the feedback resistor 8, while an alternating current flows through the loop antenna 1 and the Hall sensor 11 . The current flowing through the loop antenna 1 causes the appearance of an alternating magnetic field, the Hall sensor 11, perceiving this field, generates an alternating Hall voltage at the third and fourth inputs of the phase-sensitive bridge 10. A voltage proportional to the phase difference between the input current of the sensor is generated at the output of the phase-sensitive bridge 10 Hall 11 and magnetic field strength. The signal at the output of the phase-sensitive bridge 10 is fed to the input of the computing device 4, which performs mathematical processing of information to obtain the values of the electrophysical parameters of the underlying medium (in particular, electrical conductivity) and transmits the calculation results to the indicating and storage device 5.

The frequency of generator 2 should be changed in a certain range starting with f = 5000⋅S ^-1 , where f is the frequency in Hz, a S is the area of the loop antenna, m ² . The frequency of the generator 2 is increased until the phase shift measured by the phase-sensitive bridge 10 is 0.375 rad (22 °), after which the conductivity of the underlying medium should be measured. The measurement should be carried out at frequencies providing a phase shift lying in the range of 0.375 ... 1.9 rad (22 ... 111 °). The optimum accuracy of the conductivity measurement is achieved at phase shift angles close to π / 2 rad (90 °). Moreover, in the computing device 4, the electrical conductivity of the underlying medium should be determined by the previously given formula σ = 0.66 0,610 ⁶ ⋅ (Ф-0.2) ² / (f⋅S).

According to literary sources (see, for example, the book King R., Smith G. Antennas in material media, book 1, book 2. - M .: Mir, 1984.), such parameters as electrical conductivity, frequency of the generator signal and area antennas are included in the expressions for the magnetic field in the form of a product, therefore, it is possible to represent the totality of these parameters in the form of one dimensionless variable y proportional to the product of these parameters. If we denote by H1 (y) the real component of the magnetic field, and by H2 (y) the imaginary component of the magnetic field, then the real component has a maximum at y = 0, and the imaginary component has a minimum when the parameter value y is about 1.

If we turn to the phase characteristic Φ (y), then it can be seen that it has several extrema, therefore, in order to avoid ambiguous calculation results, it is necessary to use a plot of y values that does not exceed 5. In this connection, a restriction is introduced on the measuring range of the parameters of the underlying medium : the generator frequency is selected in the range of 2 ... 200⋅ (σ⋅S) ^-1 ⋅10 ⁴ .

The frequency of the generator 2 is changed in a certain range, starting from a known initial value until the phase shift measured by the phase-sensitive bridge 10 is in the range 22 ° ... 111 °. The electrical conductivity of the medium is calculated in computing device 4 by the formula σ = 0.66⋅10 ⁶ ⋅ (Ф-0.2) ² / (ƒ⋅S), where ƒ is the frequency of the generator 2, Hz; Ф - phase shift, rad; S is the area of the loop antenna 1, m ² .

The accuracy of measuring the parameters of the underlying environment depends on the accuracy of the manufacture and installation of the loop antenna, which is difficult to ensure for natural environments, especially when moving the measuring device, in addition, the measurement range of the parameters of the underlying environment is limited, which is a disadvantage of the prototype method and device for its implementation.

The objective of the proposed technical solution is to increase the accuracy of measuring electrophysical parameters and expand the functionality to ensure the measurement of other parameters of the underlying environment.

To solve the problem in a method for measuring the electrophysical parameters of the underlying environment, which consists in using a generator and an antenna placed in the underlying environment to measure its parameters, mathematical processing of the measurement results, determining the parameters of the underlying medium, according to the invention, the parameters of the underlying medium are measured using probes, used as an antenna with a serial circuit connected to the probes from a reference element and a contact device, otorrhea using a digital computing device, measure the oscillator frequency, which is the natural frequency of the underlying medium, which does not depend on the design parameters of the probes, and determined by the formula

(σ, ε) ƒ = π⋅σ / ε _a = 36π ² ⋅10 ⁹ ⋅σ / ε, where ƒ is the generator frequency, Hz; σ is the electrical conductivity of the underlying surface, S / m; ε is the relative dielectric constant.

An analog-to-digital converter (ADC) is connected to the device for measuring the parameters of the underlying medium, containing a generator and an antenna placed in the underlying environment for measuring its parameters, as well as a series-connected digital computing device and an indication and memory device, according to the invention, the input of which is connected to the output of the generator, and the output to the input of a digital computing device (CVC), while the generator is built on an operational amplifier, in the feedback circuit of which probes are used, using used as an antenna with a serial circuit connected to them from a reference element and a contact device, the control input of which is connected to the second output of the CVC, in addition, one probe is connected to a common connection point of the second input resistor and non-inverse input of the operational amplifier, the inverse input of which is connected with the first input resistor, and the other probe is connected to a common connection point of the load resistor and the output of the operational amplifier, and is the output of the generator, and the corresponding conclusions of the first first and second input resistor and a load resistor connected to a common bus.

The proposed method for measuring the parameters of the underlying environment is as follows.

To measure the radiation parameters, probes are used as antennas placed in the underlying medium (R. King, G. Smith Antennas in material media, book 1 - M .: Mir, 1984, p. 209) and a generator. To increase the number of measured parameters of the underlying medium, a series circuit of a reference element (for example, a capacitor) and a contact device is connected to the probes, while the generator frequency corresponds to the natural frequency of the underlying medium. The generator frequency value is used for mathematical processing in a digital computing device. In addition, the digital computing device controls the closing and opening of the circuit from the reference element and the contact device to expand the number of measured parameters of the underlying medium.

The signal of the generator is determined by the multiplication of three matrices:

- коэффициент распространения (

, со - круговая частота, R и С - эквивалентные сопротивление и емкость подстилающей среды).where a _ij are the elements of the wave matrix of the generator; RT and R ₂ are the values of the resistors of the generator circuit, Z ₁ is the wave resistance of the underlying medium;

- distribution coefficient (

, co is the circular frequency, R and C are the equivalent resistance and capacity of the underlying medium).

в последнюю формулу и выделяя действительную и мнимую часть, получим систему уравненийSubstituting

into the last formula and highlighting the real and imaginary parts, we get the system of equations

The stability boundary of self-oscillations is determined by the parameter β = Z ₁ (RT) ^-1 . To ensure the stability of self-oscillations, it is necessary that a phase balance and amplitude balance are performed. This condition corresponds to α = π and β <-1.

For calculations, we take α = π, β = -2. Then the self-oscillation frequency ƒ = ω / 2π will be determined as

The calculated capacity C can be represented as

where A is the design parameter of the probe, m; ε _a = ε ₀ ε is the absolute dielectric constant of the medium (ε ₀ = (36π⋅10 ⁹ ) ^-1 , F / m; ε is the relative dielectric constant; C is the capacitance, F.

Then, the calculated active resistance R can be represented as

where A is the same design parameter of the probe, m; σ is the electrical conductivity of the medium, S / m; R is the active resistance, Ohm.

Hence, the oscillator self-oscillation frequency is defined as

Thus, the frequency of the generator is determined not by the constructive parameters of the probes, but by the parameters of the underlying medium: σ is the electrical conductivity of the medium, S / m; ε is the relative dielectric constant. That is, the generator frequency is measured, which is equal to the natural frequency of the underlying medium, independent of the design parameters of the probes.

The structural diagram of the inventive device for measuring the parameters of the underlying environment is shown in FIG. 2, where indicated:

1.1, 1.2 - probes;

2 - generator;

3 - analog-to-digital Converter (ADC);

4 - digital computing device (CVU);

5 - display and memory device;

6 - contact device;

7 - reference element;

An RC circuit is an equivalent circuit of the underlying medium.

The proposed device contains a series-connected generator 2, ADC 3, CVU 4 and a display and memory device 5. In addition, a probe 1.1 and a probe 1.2 used as an antenna are connected to the corresponding inputs of the generator 2 and placed in the underlying medium, which is presented in the form equivalent RC circuit. A series circuit of a reference element (for example, a capacitor) 7 and a contact device 6 is connected to the probes 1.1 and 1.2, the control input of which is connected to the second output of the CVU 4.

In FIG. 3 shows a diagram of the generator, where indicated:

1.1, 1.2 - probes for measuring the parameters of the underlying medium;

2.1 - operational amplifier;

2.2 - load resistor;

2.3, 2.4 - the first and second input resistors;

6 - contact device;

7 - reference element (capacitor);

An RC circuit is an equivalent circuit of the underlying medium.

The generator 2 is built on an operational amplifier 2.1, the feedback circuit of which includes probes 1.1 and 1.2, used as an antenna for measuring the parameters of the underlying medium, presented in the form of an equivalent circuit - an RC circuit, with a connected serial circuit from a reference element 7 and a contact device 6, the control input of which is connected to the second output of the DAC 4. In this case, the probe 1.1 is connected to a common connection point of the second input resistor 2.4 and the non-inverse input of the operational amplifier 2.1, the inverse input of which is connected n resistor to the first input 2.3. The probe 1.2 is connected to the common connection point of the load resistor 2.2 and the output of the operational amplifier 2.1 and is the output of the generator 2. The corresponding conclusions of the first 2.3 and second 2.4 input resistors and the load resistor 2.2. connected to a common bus.

The proposed device for measuring the parameters of the underlying environment works as follows.

When probes 1.1 and 1.2 are connected to the underlying medium and a voltage is applied to the output of the generator 2, a signal appears whose frequency ƒ depends on the electrophysical parameters of the underlying medium. This signal using ADC 3 is converted into a digital code, which is fed to the input of a digital computing device 4. After performing arithmetic and logical operations in device 4, the result is transmitted to device 5, where it is displayed and stored.

Generator 2 is an operational amplifier 2.1, covered by frequency-selective positive feedback through a series-connected contact device 6 and a reference element 7 with connected probes 1.1 and 1.2.

When the conditions of the balance of phases and amplitudes are satisfied, such an inclusion ensures the generation of a signal whose frequency is determined by formula (1).

The contact device 6 is controlled by a digital computing device 4, as a result of which the reference element (for example, a capacitor) is connected and disconnected 7. (For example, a MOS transistor or relay contact can be used as a contact device). The frequency of the generator 2 is changed as follows:

1. The circuit of the contact device is open

ƒ ₁ = π⋅σ / ε _а = 36π ² ⋅10 ⁹ ⋅σ / ε,

2. The circuit of the contact device is closed

ƒ ₂ = π⋅σ / ε _а = 36π ² ⋅10 ⁹ ⋅σ / ε-Δƒ,

where Δƒ is the decrease in the frequency of the generator 2 relative to ƒ ₁ .

From here we get the frequency ratio

ƒ ₁ / ƒ ₂ = (C + C _e ) / C,

and the value of C is like

Based on the formula (2), knowing the design parameter of the probe A, we find the value of the absolute dielectric constant of the medium:

ε _a = ε ₀ ε = C / A.

The design parameter of probe A can be determined by calculation or by using a test sample of a medium with a known electrical conductivity of the medium σ, based on formulas (1) ... (3). Hence, parameter A will be

As can be seen from expression (6), structural parameter A is determined based on the frequencies of generator 2, the nominal value of the reference capacitor C _E, and the electrical conductivity of the test medium σ.

Using a digital computing device 4 (Fig. 2), it is possible to determine the derivatives of σ and ε parameters: dielectric loss tangent δ, skin depth, etc.

As an example, we show the use of this method for measuring the parameters of the underlying environment in different geographical zones of the Russian Federation for different seasons.

The dependence of the frequency of the generator 2 on the relative dielectric constant ε and electrical conductivity σ of the soil is shown in FIG. 4, where ε is plotted along the abscissa axis, ƒ (Hz) is plotted along the ordinate axis, and the electrical conductivity along the ordinate axis is σ (S / m).

The curves in FIG. 4 show that for winter time, when the electrical conductivity σ in many regions of Russia is close to 10 ^-6 S / m, the generator frequency will be about 100 kHz. In summer, when the electrical conductivity σ is close to 10 ^-2 S / m, depending on the relative permittivity ε, the frequency of the generator varies from 350 MHz (dry soils) to 30 MHz (wet soils). The frequency of the generator allows you to evaluate the electrophysical parameters of the soil, which are necessary for the optimal placement of the antennas of communication nodes.

Thus, the proposed technical solution allows to increase the accuracy of measurement of the electrophysical parameters of the underlying medium, as well as expand the functionality to ensure the measurement of other (additional) parameters of the underlying medium due to the parallel connection of a reference element, for example, a capacitor to probes.

Claims (11)

1. The method of measuring the electrophysical parameters of the underlying environment, which consists in using a generator and an antenna placed in the underlying environment to measure its parameters, mathematical processing of the measurement results, determining the parameters of the underlying environment, characterized in that they measure the parameters of the underlying environment using probes used in the quality of the antenna included in the generator feedback loop with a series circuit connected to the probes from the reference capacitance and contact device ulation which by a digital computing device, the oscillator frequency is measured, which does not depend on the design parameters and probes is determined by the formula ƒ ₁ = π⋅σ / ε _a = 36π ² ⋅10 ⁹ ⋅σ / ε, where ƒ is the generator frequency, Hz; σ is the electrical conductivity of the underlying medium, S / m; ε _a = ε⋅ε ₀ - absolute dielectric constant, F / m; ε is the relative dielectric constant, while measuring the absolute dielectric constant ε _{a is} carried out in the following sequence: - measure the frequency of the generator ƒ ₁ with an open contact device, - measure the frequency of the generator ƒ ₂ with a closed contact device with the connection of the reference capacitance C _e , - ε _a is determined by calculation by the formula ε _a = ε ₀ ε = C / A, Where

A is a design parameter. 2. The measurement method according to p. 2, characterized in that the electrical conductivity σ of the underlying medium is determined by the measurement results, calculated by the formula σ = ƒ ₁ ⋅ε _a / π. 3. A device for measuring the parameters of the underlying medium, comprising a generator and an antenna placed in the underlying environment to measure its parameters, as well as a series-connected digital computing device and an indication and memory device, characterized in that an analog-to-digital converter (ADC) is introduced, the input of which connected to the output of the generator, and the output to the input of a digital computing device (CVC), while the generator is built on an operational amplifier, in the feedback circuit of which is connected the medium through probes used as an antenna, with a serial circuit connected to them from a reference capacitance and a contact device, the control input of which is connected to the second output of the CVD, in addition, one probe is connected to a common connection point of the second input resistor and non-inverse input of the operational amplifier the inverse input of which is connected to the first input resistor, and the other probe is connected to the common connection point of the load resistor and the output of the operational amplifier, and is the output of the generator, and sponding terminals of the first and second input resistor and a load resistor connected to a common bus. 4. The measuring device according to claim 4, characterized in that the underlying medium is presented in the form of an equivalent RC circuit.

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