RU2248584C2 - Method for location of source of radio-frequency radiations - Google Patents

Abstract

FIELD: radio engineering, in particular, passive radio control systems.

SUBSTANCE: the method consists in measurement of the direction to the source of radio-frequency radiations, estimation of relative time delay with a subsequent computation of the coordinates of the source of radio-frequency radiations as a point of intersection of the line of direction to the source and the hyperbolis line of the position, all the measurements are taken at one receiving point, the relative time delay is determined by estimation of the discrepancy of the time of signal arrival from the source relative to the reference time scale formed on the basis of estimation of time structure of the signal source, whose position is supposed to be known, and the coordinates of the source of radio-frequency radiations are computed as the point of intersection of the line of direction to the source and the hyperbolic line of the position determined on the basis of comparison of the estimations of the discrepancy of the time of arrival of signals in time from the sources with the known and estimated location functioning in a single system of synchronization by digital (discrete) types of signals.

EFFECT: provided determination of the coordinates of the sources of USW-SHF radio-frequency radiation ranges using digital (discrete) types of signals from one point of radio control.

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Description

The invention relates to the field of radio engineering, and in particular to passive radio monitoring systems, and, in particular, can be used in systems for determining radio-emitting means of the VHF-microwave ranges operating in the radio network as slave stations and using digital (discrete) types of signals, including the number of subscribers of communication systems with mobile objects.

Known methods of positioning, which can be used to determine the coordinates of radio emission sources (IRI), for example:

1. The goniometric method of positioning [1]. This method is used if there are several (at least two) radio direction finding devices spaced in space. The location is carried out by calculating the point of intersection of the lines of bearings in the IRI.

The disadvantages of this method are:

- the need to use several spacers distributed in space;

- to calculate the coordinates of the IRI, a communication system is needed that connects radio direction finding means spaced in space;

- the accuracy of positioning significantly depends on the relative position of the direction finding devices and the controlled object.

2. The difference-range measuring method [1] is based on measuring the differences in the distances from the IRI to the point of radio monitoring. These differences are found by measuring the relative time delays by the correlation method. At the same time, at least three radio monitoring points spaced in space are necessary.

The disadvantages of this analogue are:

- the need to use several spacers distributed in space complicates the structure of the positioning system;

- for the functioning of the differential rangefinder positioning system, the radio monitoring points must operate in synchronous mode, as a result of which the accuracy of the positioning significantly depends on the accuracy of binding to the system of single time.

3. In [2], a device is described that allows one to determine the location of a radio transmitter from one point by measuring the bearing and the relative time delay of the signals directly and reflected from a nearby object, and it is postulated that the distance to the reflecting object is known. At the same time, the presence of a reflecting object is not always carried out in practice, which does not allow us to talk about the applicability of this approach to measuring the coordinates of a source of radio emissions with a given reliability, in addition, a signal reflected from another object can be received at the input of the receiver.

Of the known methods, the closest analogue (prototype) of the proposed method according to the technical essence is a method that combines the features of the goniometric and extreme-rangefinding methods of location - the goniometric-differential-rangefinding method of location [1]. The goniometric-difference-ranging method is based on measuring the angular position of the source and the difference in the distance from it to the receiving points (radio monitoring points), i.e. essentially combines both of the previously described methods. In this case, it is enough to have two receiving points, on one of which the angular direction (azimuth α) is determined, and on the other - the distance difference from the receiving points to the source (Δ R). The position of the source is defined as the point of intersection of the bearing on the IRI and the surface of the hyperboloid. The distance to the source is determined by the expression

where D is the distance between the points of radio monitoring.

The functioning of the positioning system in accordance with this method is as follows.

At one of the monitoring points, the direction (azimuth) is measured in Iran. At the same point, the time of arrival of the signal from the IRI is measured. The second paragraph only measures the time of arrival of the signal. Moreover, all measurements should be made at the command of one of the points of radio monitoring. It is obvious that it is necessary to have communication lines between the points of radio monitoring.

Given that, ultimately, the necessary information is not the absolute time of arrival of the signal, but the relative time delay of the signal between the monitoring points, the necessary data on the time delay can be obtained using the cross-correlation method. In this case, a communication line between the radio monitoring points is also necessary, and in this case they must be tightly synchronized. The calculation of the actual coordinates of the IRI is carried out at the point of radio monitoring, which measures the bearing on the IRI. In this case, the direction to the IRI is determined by the bearing, and the range is determined according to (1).

The disadvantages of the prototype method:

1. The need to use at least two receiving points to determine the coordinates of the IRI and, as a consequence, the need for a communication line between the separated points.

2. The accuracy of determining the coordinates of the IRI substantially depends on the accuracy of the binding to a single time system.

The aim of the present invention is to develop a method for determining the coordinates of the IRI VHF-microwave ranges from one point of radio monitoring.

This goal is achieved by the fact that in the known method of determining the IRI, which includes measuring the direction to the IRI, measuring the difference in distance from the radio monitoring points to the controlled IRI, and then calculating the coordinates as the intersection of the bearing line and the hyperbolic position line, instead of two spaced apart radio monitoring points, it is used only one performing the same operations (measuring the direction to the IRI and measuring the time of arrival of the signals), while the location is based on the intersection point of two position lines, one of which is a bearing on the IRI, and the second is determined by comparing the time delays in the propagation of signals from sources operating in a single synchronization system.

Comparative analysis with the prototype shows that the inventive method is distinguished by the presence of only one point of radio monitoring, with the appropriate technical solution. Thus, the claimed method meets the criteria of the invention of “novelty”.

The source data (conditions) for implementing the method of single-point location are:

- IRI signal digital (discrete), including with a complex time-frequency structure with a clearly defined period;

- the location of at least one correspondent from the radio network is a priori known;

- the frequency-time structure of the signal (frequency (period) of the following pulses of clock (cycle) synchronization) is a priori known (or accessible to estimation).

Comparison of the proposed method with other similar methods shows the need to perform known operations - measuring the direction to the IRI and measuring the time of arrival of signals. However, the introduction of the above set of source data made it possible to abandon the need to use several receiving points for determining the IRI of the VHF-UHF bands operating in the radio network as slave stations and using digital (discrete) types of signals. In this case, instead of the difference in the arrival time of the signals at several radio monitoring points spaced in space, an estimate of the difference in the arrival time of the signal and the reference time scale is used, which allows us to conclude that the proposed method meets the criterion of "significant differences".

The claimed method is illustrated by the illustrations presented in figures 1-6.

Figure 1 - Timing diagrams of sequences of pulses.

Figure 2 - Geometric interpretation of the method of location from one point.

Figure 3 is a diagram explaining the assessment of the location, with the location of the controlled IRI behind the radial line of position (source in the I quadrant).

4 is a diagram explaining the assessment of the location, with the location of the controlled IRI behind the radial line of position (source in the III quadrant).

5 is a diagram explaining the assessment of the location, with the location of the controlled IRI inside the radial line of position (source in the I quadrant).

6 is a diagram explaining the assessment of the location when the controlled IRI is located inside the radial position line (source in the III quadrant).

The location of the IRI according to the wilted method is clearly illustrated in Fig.1,2. Figure 1 presents the timing diagrams of sequences of pulses, while figure 1 the following notation: A - meter (point radio monitoring); In - IRI 1 with known coordinates; C - IRI 2, the location of which is determined; U _IRI1 (t) - pulse sequences of signals from IRI 1, the location of which, in accordance with the list of restrictions, is a priori known; t _1B (t _1C ) - time of the beginning of the transmission of the pulse (parcel, sign, packet) IRI 1 (IRI 2) with a period of repetition of T _P ; t _1A (t _2A ) is the time of registration at point A of the moments of arrival of signals from IRI 1 and IRI 2, respectively; Δ τ _{B, C} is the discrepancy in time of the moment of the start of signal transmission from the IRI 2 relative to the timeline of the IRI 1; Δ τ _{C, A} is the time delay of the signal from the IRI 2 to the meter (A); Δ τ _1,2 is an estimate of the time difference between the moment of registration of the signal from the IRI 2 relative to the reference scale formed on the meter (A) based on the results of the evaluation of the temporal structure of the signal from the IRI 1.

The key link in the implementation of the method is the justified assumption that the algorithm for operating the radio synchronous data network allows you to interpret the signal received from IRI 2 as a signal transmitted from IRI 1 and conditionally relayed by the receiving and transmitting device of IRI 2 through an unknown but integer number of cycles.

That is, the following expressions must be true:

where K is an integer number of signal periods in the time interval t _1C -t _1B ; C is the propagation velocity of radio waves.

As a result, in evaluating the time parameters of the input stream on the meter (A), the delay (or lead) of the signal (Δ τ _1,2 ) from IRI 2 (point C) relative to the nearest marker of the reference time scale formed on the meter should be determined

provided that the IRI 2 (point C) is topologically located at a distance greater than the calculated radius R (determined by the IRI 1, the location of which is known) (figure 2), or

Then the distance

₂ с началом в точке А и направлением, соответствующим пеленгу на ИРИ 2.The uncertainty (±) in expression (5) shows that theoretically the equation can have two roots C and C *, the values of which are located on both sides of the point D located at the intersection of the equal-distance line with radius R and vector

₂ with the beginning at point A and the direction corresponding to the bearing on Iran 2.

It is known that a fixed sum of distances to two given fixed points is described by a second-order curve (an elliptic position line). The product with Δ τ _1,2 is equal to the sum of the distances (BC + CD) (figure 3). Then, if we choose points B and D as fixed points formed by the intersection of bearings on IR1 and IR2 and circles of radius AB centered at point A, then using the measured value of the distance difference parameter R _c = BC + CD = сΔ τ _{1, 2} , we can construct an ellipse with foci at points B and D, which is described by the equation

, определенной углом (α _С), и эллиптической линии положения на плоскости определяют две точки, одна из которых соответствует оценке в местоположении ИРИ2 (фиг.3).Bearing line intersection

, defined by the angle (α _С ), and an elliptical line of position on the plane define two points, one of which corresponds to the estimate at the location of IRI2 (figure 3).

At the same time, a hyperbolic position line will correspond to a constant difference in distances with respect to two fixed points. Then, if we choose the same points B and D as fixed points (Fig. 5), then the value of R _p = BC * -C * D will also correspond to the value of cΔ τ _1.2 , and from the set of data presented it is possible to construct a hyperbolic line the position described by the equation

и гиперболической линии положения на плоскости определяют две точки, одна из которых будет соответствовать оценке местоположения ИРИ2 (фиг.3).Bearing line intersection

and a hyperbolic line of position on the plane define two points, one of which will correspond to the location estimate of IRI2 (figure 3).

Thus, the claimed location method is a combined use of three position lines, two of which (elliptical or hyperbolic) are used depending on the relative topological location of the meter and a pair of controlled sources on the plane.

The decisive rule that determines the choice of the mathematical apparatus for constructing the position line will be based on the fulfillment of the inequality:

- if cΔ τ _1,2 > BD, then cΔ τ _1,2 should be considered as the sum of BC + CD (figure 3), and to calculate the coordinates of the IRI an elliptical position line is built;

- if cΔ τ _1,2 , <BD, then the value cΔ τ _1,2 should be considered as the BC * -C * D difference (Fig. 3), and a hyperbolic position line is used to calculate the coordinates of the IRI.

Then false values in the assessment of the location of the IRI should be considered: for the first case - the roots falling into the region of a circle of radius R = AB; for the second case, the roots of the equations located outside the radius R = AB.

Figure 4 presents a graphical interpretation for the location options of the controlled IRI in the 3rd quadrant of the coordinate system with a zero mark at point A for AC> AB, and in Fig.6 - IRI in the fourth quadrant with AC <AB to confirm the functionality of the proposed one-point method coordinate measurements with an omnidirectional arrangement of control sources relative to the meter.

In order to derive an analytical expression characterizing the dependence of the coordinates of IRI on the measured values, it is necessary to solve the system of equations of the straight line determined by the bearing on IRI2 and the elliptical (hyperbolic) line of position of IRI2 in the Cartesian coordinate system.

We consider the system of equations of the bearing and ellipse lines (hereinafter, we omit the indices for x and y, implying that they correspond to IRI2)

where y ₀ , x ₀ are the initial coordinates of the bearing line; k = tgα; α is the angle determined by the azimuth on IR2; d = BD.

In turn, the system of equations of the bearing line and the hyperbolic position line will have the form

Selecting the origin D (Fig. 3, Fig. 5) as the origin (directly entering into the expression for the bearing line in IR2) and putting y ₀ = 0, x ₀ = 0 to simplify the calculations (it should be noted that such an assumption is not least does not limit the generality of the solutions obtained, since it actually comes down to the transformation of coordinate systems), we obtain y = kx, then

Solutions (10) and (11) with respect to x have the form

Thus, we obtained relations for the coordinates of the points of intersection of the bearing line with elliptic (6) and hyperbolic (7) position lines.

Substituting the found x into the expression y = kx, we obtain a set of Cartesian coordinates satisfying systems (8), (9).

на ИРИ2 с гиперболической и эллиптической линиями положения совпадают. Действительно, для того, чтобы точки пересечения линии пеленга

с эллиптической и гиперболической линиями положения совпадали, необходимо и достаточно, чтобы х_c=х_p, y_c=y_р, в этом случае имеют место следующие равенстваFrom the expressions (12), (13) it follows that systems (8), (9) have four different pairs of roots and further elimination of the ambiguity, at first glance, causes difficulties. At the same time, for (12), (13) it can be shown that the points of intersection of the bearing line

on IR2 with the hyperbolic and elliptic lines the positions coincide. Indeed, in order for the points of intersection of the bearing line

the positions coincided with the elliptic and hyperbolic lines, it is necessary and sufficient that x _c = x _p , y _c = y _p , in this case the following equalities hold

, определяемому коэффициентом k, следовательно, не являются решением систем (8) и (9) соответственно, что противоречит нашему предположению.Suppose that this is not so, but x _c , y _c and x _p , y _{p are} roots of the same sign, found according to (12), (13), which are solutions of systems (8), (9), respectively, then, obviously, the following equalities must not be satisfied, which follow directly from (14) y _c = kx _p , y _p = kx _c , but if they are not satisfied, the points with coordinates (x _s , y _s ) and (x _p , y _p ) do not belong vector

determined by the coefficient k, therefore, are not a solution to systems (8) and (9), respectively, which contradicts our assumption.

Thus, the roots determined according to (12), (13) will coincide and the problem of further resolving the ambiguity does not arise.

To eliminate ambiguity given by sign ±, one can use the following rule: if IRI2 lies in I or II in the quadrants of the true value x takes the value ₂ (12), (13) with a plus sign when sΔ τ _1,2> BD and minus with cΔ τ _1,2 <BD and, conversely, with a minus sign with cΔ τ _1,2 > BD and plus with cΔ τ _1,2 <BD, when located in III or IV quadrants (the quadrant can be considered a priori known, defined bearing).

Solutions (12), (13) determine the coordinates of the IRI2 relative to the point D, the position of which is known (the point of intersection of the bearing line and the radial position line). The coordinates of the point D in the Cartesian coordinate system relative to the point (x _A , y _A ) can be calculated by the expressions

- расстояние между точками А и В (фиг.2а, фиг.3 а); (х_в, y_в)- координаты ИРИ1 (местоположение которого известно).Where

- the distance between points A and B (figa, figa); (x _in , y _in ) - coordinates of IRI1 (whose location is known).

Thus, we have two systems of Cartesian coordinates - the first relative to point D, the second relative to the location point of the monitoring station (point A) (x, y). To calculate the coordinates of the desired point in a single coordinate system, you can use the following expressions

, знак выбирается таким образом, что если с Δ τ _1,2>BD выбирается плюс, при с Δ τ _1,2<BD - минус.Where

, the sign is chosen in such a way that if plus Δ τ _1,2 > BD, plus is chosen, and if Δ τ _1,2 <BD, minus is chosen.

Thus, the analytical expression (12) allows you to calculate the coordinates of the IRI from one point and describes the claimed method of location, which allows you to determine the location of the source being monitored if there are appropriate technical means at the radio monitoring station.

The necessary technical means for implementing the claimed method are widely known. As a means of determining the angular position of the IRI, you can use any of the existing direction finding tools, a given frequency range that provides the required direction finding accuracy, for example, a direction finder described in [3] or [4]. To measure the time of arrival of the signal, you can use the correlation method [2] on the basis of any radio receiver of the corresponding frequency range in which the autocorrelator is additionally introduced. In addition, given that a discrete class of signals is considered, it is possible to directly measure the time of arrival of the pulse and the necessary relative time delay to calculate as the difference between the time of arrival of the signal and the nearest marker of the reference time scale

As can be seen from the above description, the claimed method of positioning does not require several receiving points, in addition, there is no need for binding to a single time system, and the accuracy of positioning depends only on the accuracy of the assessment of the necessary parameters.

Therefore, we can conclude that the goal set before the invention - the development of a method for determining the coordinates of the IRI VHF-microwave ranges from one point of radio monitoring - is achieved.

The claimed method can be applied to determine the location of mobile subscribers of communication systems with mobile objects, in which the location of the base station is a priori known.

The technical and economic effect due to the application of this method consists in reducing the number of technical means for determining the location of radio emission sources and increasing the accuracy of positioning, and therefore, increasing the efficiency of passive radio monitoring systems in general.

The quantitative value of the expected technical and economic effect of the use of the proposed method depends on the type of system to be monitored and the importance of this system; its determination is possible after the implementation of the proposed method in specific monitoring systems.

Sources of information:

1. Karavaev VV, Sazonov VV Statistical theory of passive location. - M.: Radio and Communications, 1987. - 240 p.

2. UK patent No. 2094089 A MKI G 01 S 13/86 from 09/08/1982

3. RF patent №2000100834 / 09 of 01/17/2000

4. The Federal Republic of Germany patent No. 2328720 MKI G 01 S 3/4 of 05/06/76

Claims (1)

The method of determining the sources of radio emissions, which consists in measuring the direction to the source of radio emissions, estimating the relative time delay, followed by calculating the coordinates of the source of radio emissions as the point of intersection of the direction line to the source and the hyperbolic position line, characterized in that all measurements are made at one receiving point, while the relative the time delay is determined by assessing the discrepancy in the time of arrival of the signal from the source relative to the reference time scale s, formed on the basis of an estimate of the temporal structure of the source signal, the location of which is assumed to be known, and the coordinates of the source of radio emissions are calculated as the point of intersection of the direction line to the source and the hyperbolic position line, determined by comparing the estimates of the difference in time of arrival of signals from the sources with the known and estimated location, functioning in a single synchronization system with digital (discrete) types of signals.

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