RU2334244C1 - Method of radio radiation source location detection - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: within common method of radio radiation source (RRS) location detection, including RRS bearing measurements and detection of RRS spacing, additionally at the same height of electromagnetic field (EMF) intensity amplitude of RRS E₁, E₂ are detected in two points spaced respectively by distance b along RRS bearing line, and RRS spacing is calculated by formula

Thus RRS EMF intensity amplitudes in two points shall be measured simultaneously through formation of synchronous time sampling. In case of measurement "release" as E₁ E₂ due to random, such measurements are filtered and not used for spacing detection.

EFFECT: increased accuracy of radio source location detection procedure at simultaneous expansion of their class.

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Description

The invention relates to passive radar and is intended to determine the location of radio emission sources (IRI).

A known method of detecting and determining the coordinates of the IRI, including receiving radio emission from the IRI in at least three spatially separated points of reception with subsequent transmission of the received signals to a central point, determining the square of the module of the complex mutual correlation functions and the mutual delay of the moments of arrival of electromagnetic waves (RF patent No. 2285937, G01S 5/05, 2006).

This method has limitations on the accuracy of determining the location of the IRI emitting narrowband signals. The accuracy of measuring the mutual delay of the arrival times of the IRI signal at the receiving points is limited by the time of the mutual correlation of the signals. The duration of the correlation pulse is inversely proportional to the frequency band of the processed signals ("Theoretical Foundations of Radar", edited by Ya.D.Shirman, M., Sov. Radio, 1970, pp. 498, 499). The simulation results in analog are given for a broadband signal with a frequency band of 3 MHz.

The closest to the proposed technical essence and the achieved positive effect is a goniometric-differential-ranging method for determining the location of the IRI, including measuring from one bearing position on the IRI and the difference in distances from the IRI to two receiving points. The location of the IRI is determined by the point of intersection of the bearing line with the hyperbola of the corresponding difference in the distances to the IRI (Theoretical Foundations of Radar, edited by Ya.D.Shirman, M., Sov. Radio, 1970, pp. 497 ... 511 )

The practical implementation of the correlation-base location, which includes an analogue and a prototype, is associated with establishing a correspondence between signals received at at least two receiving points from the same IRI, and determining the relative delay time τ. An indicator of the potential accuracy of the measurement of the delay time is the variance of the relative measurement error equal to

where F _E is the effective width of the spectrum of the complex envelope of the signal;

- параметр обнаружения, равный отношению сигнал/шум на выходе согласованного фильтра;

- detection parameter equal to the signal-to-noise ratio at the output of the matched filter;

E is the amplitude of the signal;

N ₀ is the spectral density of noise,

("Radio engineering systems", M., "Higher School", 1990, pp. 127 ... 134).

From (1) it follows that the potential accuracy of measuring the information parameter τ is determined by the signal energy and the effective spectrum width of the complex signal envelope. The accuracy of determining the location of the IRI in this way depends on the signal class, type and modulation parameters. IRI with signals of type N0N (carrier) cannot be measured using this method.

Currently, a large fleet of civilian and military RESs is used, using narrow-band signals, signals with a radiation band comparable with the band of the information (modeling) signal.

These types of narrow-band signals include telegraphy - 10 ... 100 Hz, single-band modulation - 3 kHz, teletype - 4.8 kHz, low-speed Internet - 12.5 kHz, etc.

The technical result of the invention is to provide the location of the IRI with signals of the type N0N (carrier) and to increase the accuracy of determining the location of the IRI emitting narrowband signals, while expanding the class of IRI.

The technical result is achieved by the fact that in the known method of determining the location of the IRI, including measuring the bearing on the IRI and determining the distance to the IRI, they additionally measure at the same height the amplitude of the electromagnetic field strength (EMF) IRI E ₁ , E ₂ at two points respectively spaced by distance b along the line of the bearing to the IRI and determine the range to the IRI in accordance with the formula

The principle of the proposed method is based on the fact that the rate of decrease in the amplitude amplitude of the EMR-E EMF along the bearing line corresponds to a specific distance to the IRI-g and does not depend on the IRI-E energy potential.

- скорость роста (убывания). На фигуре 1 показано, что модуль градиента амплитуды напряженности ЭМП соответствует конкретным удалениям r и r+b, его величина не зависит от энергопотенциала ИРИ Э>Э', а убывание амплитуды происходит в противоположную сторону от ИРИ по линии пеленга. Для различных условий распространения радиоволн существует определенная аналитическая зависимость Е(r), поэтому способ может быть применен к конкретным условиям распространения радиоволн.It is known from the theory of scalar field that the rate of change in the amplitude of the EMF intensity is described by its gradient gradE, whose vector shows the direction of the fastest growth, and the modulus

- growth rate (decrease). The figure 1 shows that the modulus of the gradient of the amplitude of the EMF intensity corresponds to specific removals r and r + b, its value does not depend on the energy potential of the IRI E> E ', and the decrease in amplitude occurs in the opposite direction from the IRI along the bearing line. For various propagation conditions of radio waves, there is a certain analytical dependence E (r), therefore, the method can be applied to specific propagation conditions of radio waves.

The proposed method is considered in relation to the practically important case of the propagation of terrestrial VHF radio waves, when the height of the transmitting - h ₀ and receiving - h ₁ , h ₂ antennas exceeds the wavelength - λ.

амплитуды напряженности ЭМП в двух разнесенных точках 1 и 2 на расстояние b определяется формулой Б.А.Введенского (М.П.Долуханов, «Распространение радиоволн», М., «Гос. издат.», 1960 г., стр.77)Provided

the amplitude of the EMF intensity at two spaced points 1 and 2 at a distance b is determined by the formula of B. A. Vvedensky (MP Dolukhanov, “Propagation of Radio Waves”, M., “State Publishing House”, 1960, p. 77)

In the proposed method, the rate of decrease in the amplitude of the EMF EMI intensity is estimated by the ratio of the values of E ₁ / E ₂ measured at spaced points 1 and 2, respectively, at a distance b along the bearing line and at the same height h ₁ = h ₂ .

Then the ratio of expressions (3) and (4) takes the form

Having solved the quadratic equation (5) with respect to r, we find expression (2) for determining the range to the IRI

In this case, the measurement of the amplitudes of the EMF electromagnetic radiation at two points should be carried out simultaneously by forming a synchronous time sample.

In the case of "emissions" of measurements, when E ₁ ≤E ₂ due to random fluctuations, such measurements are filtered out and are not used in determining the range.

The experiment confirms the calculated dependence according to formula (2), the results of which for b = 100 m are shown in the table.

A comparative analysis of the claimed solution with the prototype shows that the proposed method differs from the known number of new actions on the IRI signal:

- simultaneous measurement of the amplitude of the electromagnetic field IRI at two points spaced along the bearing line at a distance b and at the same height;

- calculation of the distance to the IRI in accordance with the expression (2).

By the totality of actions on the IRI signal, the proposed method is amplitude. In the study of other well-known technical solutions in this technical field, the specified set of features that distinguishes the invention from the prototype has not been identified, which indicates the compliance of the claimed invention with the eligibility criterion of "novelty".

Search results for known technical solutions in this and related fields of technology in order to identify features that match the distinguishing features of the proposed method have shown that no solutions having features matching its distinctive features have been identified in publicly available information sources. The prior art also does not confirm the popularity of the influence of the distinctive features of the claimed invention on the technical result indicated by the applicant. Therefore, the claimed invention meets the condition of "inventive step".

The proposed method for determining the location of radio emission sources is industrially applicable, since the combination of characteristics characterizing it provides the possibility of its existence, performance and reproducibility, and known materials and equipment can be used to implement the method.

Figure 1 shows a diagram of the change in the amplitude of the electromagnetic field of the IRI depending on the distance to the IRI, figure 2 is a structural diagram of a system that implements the proposed method, figure 3 is a relative arrangement of elements (devices) of the system in the goniometric and azimuthal planes.

The table shows the values of E ₁ / E ₂ calculated for various distances from the IRI, with b = 100 m.

The system that implements the proposed method (figure 2) contains a direction finder (RP) 1, control outputs (2 - code. Frequencies) that are connected to the control inputs (2) of two measuring receivers (IP) 2.1, 2.2, the information outputs of which are connected to the information inputs of the range calculator 3, while the sampling time synchronizer 4 is connected to the control inputs (3) of the measuring receivers 2.1, 2.2 and the range calculator 3.

The measuring receiver 2.1 is placed at the same position as the direction finding 1, and the measuring receiver 2.2 is placed at a distance b in the direction of increasing the distance to the IRI (Fig. 3).

The distance b between the measuring receivers 2.1, 2.2 is determined from the condition under which the reflected rays from the earth's surface were added with a direct beam at measurement points 1, 2, come from one Fresnel half-band.

Along the bearing line in the IRI, the distance between the measuring receivers 2.1, 2.2 is limited by the dimensions of the large (longitudinal) axis of the Fresnel zone b≤r _x1 .

The permissible deviation of the measuring receiver 2.2 from the bearing line on the IRI is limited by the angle φ formed by the IRI and the small (transverse) axis - r _{y1 of} the Fresnel zone.

The principle of operation of the system is as follows.

The direction finder 1 at the control input / output (2) synchronously tunes the measuring receivers 2.1, 2.2 to the frequency of the IRI signal.

Synchronously received signals by measuring receivers 2.1 and 2.2 are of the form:

S ₁ (t, E ₁ ) = E ₁ · S ₀ (t), S ₂ (t, E ₂ ) = E ₁ · S ₀ (t), for E ₁ > E ₂ ,

where E ₁ , E ₂ is the amplitude of the EMF EMI intensity to be measured, and is an unknown information parameter of the signal;

S ₀ (t) - factor determining the waveform in accordance with the type of modulation and having a unit energy

The energy of the received signals is determined

An indicator of the potential accuracy of measuring the amplitude of the EMF is the variance of the relative measurement error equal to

("Radio engineering systems", under the editorship of Yu.M. Kazarinov, M., "Higher School", 1990, pp. 123, 124).

Thus, the information parameter determines the energy of the signal and does not depend on the type and parameter of modulation.

To increase the accuracy of measuring the amplitude of EMF EMI, it is necessary to increase the ratio of energy signal / noise at the output of the linear part of the measuring receivers 2.1 and 2.2.

The received signals of the IRI receivers 2.1 and 2.2 are digitized, the sampling period of the signal is dt≤ΔF / 2, where ΔF is the bandwidth of the linear path of the measuring receiver. The sample size is determined from the condition of the necessary averaging of the measurement result.

The synchronism of digital samples of the IRI signal by receivers 2.1 and 2.2 is set by the sampling time synchronizer 4.

The results of measuring the amplitudes of the field strength of the IRI signal are simultaneously read into a range calculator 3, where, in accordance with formula (2), the range to the IRI is determined.

Analysis of expression (6) shows that the potential accuracy of measuring the information parameter about the distance to the IRI does not depend on the signal class (type and modulation parameters), which has an advantage compared to the prototype.

Therefore, the accuracy of determining the location of the IRI does not depend on the class and spectral width of the signal.

Table

r, km 0.5 one 2 3 four 5 6 7 8 9 10 E ₁ / E ₂ 1,562 1,234 1,108 1,070 1,052 1,041 1,034 1,029 1,025 1,023 1,021

Claims (1)

A method for determining the location of a source of radio emission, including measuring the bearing to a source of radio emission and determining the distance to the source of radio emission, characterized in that it is additionally measured simultaneously at the same height of the amplitude of the electromagnetic field of the radio emission source E ₁ , E ₂ at two points respectively spaced apart by distance b along the line bearing and determine the distance to the source of radio emission in accordance with the formula

in this case, when E ₁ ≤E ₂ , then such measurements are filtered out and are not used in determining the range.

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