RU2234712C2 - Method for determining coordinates of moving radio irradiation source with unknown parameters and apparatus for performing the same - Google Patents

Abstract

FIELD: passive radar systems.

SUBSTANCE: method comprises steps of receiving set of successive measurements of angular coordinate of moving irradiation source; measuring frequency of irradiation received by two receivers whose antennae move relative to irradiation source with different but known velocity values; calculating on base of measurement results radial velocity of irradiation source at each time moment of measuring; beginning from third measurement calculating in addition range until irradiation source. Invention allows to eliminate very complex problem caused by use of triangular method for determining coordinates of large number of irradiation sources, namely removing false points of crossing bearings.

EFFECT: simplified high-reliability method and apparatus for determining coordinates.

2 cl, 4 dwg

Description

The invention relates to the field of passive radar and can be used to solve some tasks of the air defense and space defense of the country, as well as in scientific research.

Known methods for determining the coordinates of moving radiation sources, based on the reception, extraction and processing of direct radiation, for example, correlation-basic. The disadvantage of such methods is their complexity. / Theoretical foundations of radar. Ed. J.D. Shirman. Air Defense Forces of the country, 1968, pp. 394-399 /.

The closest in technical essence to the proposed method is the triangulation method for determining coordinates, selected as a prototype, based on the reception, isolation and processing of direct radiation by two or more receiving devices located at different geographical locations spaced apart from each other by a distance, called the base, location angular directions to the radiation source at each receiving point and calculating the coordinates of the radiation source at the intended angles and the known separation base of the receiving points but direct radiation. / Theoretical foundations of radar. Ed. J.D. Shirman. Air Defense Forces of the country, 1968, pp. 391-392 /. These coordinates are the coordinates of the points of intersection of bearings taken at all points of reception. The triangulation method has two main drawbacks: it is the obligatory availability of high-quality communication channels between receiving points and the computer, and, most importantly, the presence of so-called false bearing intersection points with more than one radiation source. Sifting out false intersection points is an extremely difficult task, especially with a large number of radiation sources.

Also known devices used to solve triangulation problems, working on a direct / radiated / signal. / Handbook of electronic systems. Ed. V.Kh. Krivitsky. M .: Energy, 1979, pp. 165-168 /. Also known is the so-called direction finder, selected as a prototype, receiving a direct signal that determines the azimuth to the radiation source, containing a series-connected antenna and a receiving device, as well as an antenna control unit. / Handbook of electronic systems, ed. B.Kh. Krivitsky. M .: Energy, 1979, pp. 169-170 /. This direction finder at the time of minimum signal at the output of the receiving device from the angular position of the antenna determines the azimuth of the radiation source. The disadvantage of this device is that, working on a direct signal, it can, in principle, determine only one coordinate - azimuth, which forces us to use a range of direction finding radios on the ground to determine the range.

The objective of the invention is to develop a method for determining the coordinates of a moving radio emission source with unknown parameters, which does not require direction finders spaced on the ground, thereby avoiding the solution of the problem of sifting false crossover points of bearings, and the mandatory use of high-quality communication channels between direction finders and a calculator, as well as a device for implementing this method .

The technical result of solving the problem of the invention is a method and device for determining the coordinates of a moving radiation source, which, in addition to azimuth, can also determine the distance to a moving radiation source with unknown parameters from the results of measurements of the parameters of the received signal in only one geographical point of reception.

The technical result is achieved by the fact that in a method for determining the coordinates of a radiation source, based on the reception, extraction and processing of direct radiation by two or more receiving devices / receivers /, spaced on the ground at a distance called the base, measuring angular directions to the radiation source in each geographical location receiving direct radiation and calculating the coordinates of the radiation source for the angles found and the known separation range of direction finders, instead of determining the angular direction to the radiation source In the second and other points of direct radiation reception, in only one geographical point of reception, the angular direction is measured sequentially to the radiation source, and the frequency of the received signal allocated by the receiver of the main direction-finding channel and the receiver of the additional channel are sequentially determined, each the receiver is connected to its antenna, which move relative to the radiation source with predetermined but different radial velocities find the frequency difference of the direction finding and additional channel signal, from the found frequency difference, the measured values of the direction finding and additional channel signal frequencies, known radial antenna velocities, calculate the radial velocity of the radiation source using one of the formulas

Or

from the relations

calculate the angular direction of the linear velocity vector / course angle / radiation source at the time of the first measurement of the azimuth and frequency β _k and γ _k - the angle of rotation of the linear velocity vector due to the curvature of the path of the radiation source for the time interval between the first and second measurements, from the measured values azimuth and calculated values of the radial velocity of the radiation source, course angle and angle of rotation of the vector of linear velocity of the radiation source or by the formula

either by the formula

calculate the distance to the radiation source at each moment of measuring the azimuth and frequency, with the exception of the first and second moments.

In these formulas

V _r is the radial velocity of the source;

f ₁ - signal frequency in the main direction-finding channel;

V _ra1 is the radial speed of the direction finding antenna;

V _ra2 is the radial speed of the antenna of the additional channel;

f ₂ - signal frequency in the additional channel;

c is the speed of light;

i - 3, 4, 5 ... - serial number of the measurement,

α _i - azimuth of the source at the i-th moment of measurement;

β _to - the angular direction of the linear velocity vector of the radiation source at the beginning of the k-th section of the trajectory,

k - 1, 2, 3 ... - the serial number of the section of the trajectory of the radiation source, the distance to which is determined at the i-th moment,

γ _to - the angle of rotation of the linear velocity vector due to the curvature of the trajectory during the time between the first and second measurements of azimuth and frequency on the k-th section of the trajectory;

r _i is the distance to the source at the i-th moment of measuring the azimuth and frequency;

t _i is the time of the i-th azimuth and frequency measurement.

To implement the proposed method, a direction finder containing a receiver, the input of which is connected to the output of the antenna, the antenna and the antenna control unit constituting the direction-finding channel, has an additional channel that includes a receiver, a movable antenna, the output of which is connected to the input of the receiver of the additional channel, moving relative to source of radiation at a speed V _ra, antenna control unit that moves a movable antenna by a given law, dual frequency meter, a first input of which Cpd is connected to the output of the direction finding channel receiver, the second input of the frequency meter is connected to the output of the additional channel receiver, a computer whose information inputs are connected to the corresponding outputs of the frequency meter and antenna control units, a synchronizer, the control outputs of which are connected to the corresponding inputs of the antenna control unit, frequency meter and calculator.

Figure 1 shows a structural diagram of a device that implements the proposed method for determining the coordinates, and conventionally shows a movable radiation source. Figure 2 shows an arbitrary curved path and its approximation by segments of circles of different radii. Figure 3 shows a geometric diagram explaining the derivation of the formula for the distance to the radiation source with a curved path of movement of the source. Figure 4 shows a geometric diagram explaining the derivation of the formula for the distance to the radiation source in the straight sections of the path of the source.

A device for determining the coordinates of a moving radiation source with unknown parameters (Fig. 1) contains an antenna 1, a receiver 2, an antenna control unit 3 forming a direction finding channel 4, a mobile antenna 5 controlled by a control unit 6, a receiver 7 forming an additional channel 8, two-channel frequency meter 9, calculator 10 and synchronizer 11.

The principle of operation of the proposed device is as follows.

At the input of the antenna of the direction finding channel 4, the oscillations of frequency f come from a source moving with a radial speed V ₂ . At the same time, the same vibrations arrive at the input of the antenna 5 of the additional channel 8. The antenna control unit 3 controls the movement / rotating or swaying / of the antenna 1 in order to determine the azimuth of the radiation source, and the antenna control unit 6 controls the movement of the antenna 5 relative to the radiation source with a radial velocity V _ra . From the control unit 3, information about the azimuth of the source α, and from the control unit 6, information about the radial speed of the antenna 5 V _ra is digitally supplied to the corresponding inputs of the calculator 10.

From the output of the antenna 1 to the input of the receiver of the direction-finding channel the frequency fluctuation f = f ₁ / frequency of the direction-finding channel /. After isolation and amplification by the receiver 2, this frequency oscillation f _{1 is} supplied to the first input of the frequency meter 9 to determine the frequency value f ₁ . From the first output of the frequency meter, information on the value of the frequency f ₁ is digitally supplied to the calculator 10. The input of the antenna 5 receives the oscillation of the same frequency f, but the output of the antenna 5 receives the oscillation of the frequency f ₂ = (f + Δ F F ) ≠ f ₁ , since in the value of the frequency f ₂ there is a component of the Doppler shift due to the radial speed V _{ra of the} antenna 5. After isolation and amplification by the receiver 7, the frequency fluctuations f ₂ are input to the second channel of the frequency meter. Information on the value of the frequency f ₂ in digital form from the output of the second channel of the frequency meter is fed to the calculator 10. Due to the discrete reading of information on the calculator at times t ₁ information from the azimuth of the radiation source α (t _i ) is received from the signal frequency in the direction finding channel f ₁ (t _i ), the signal frequency in the additional channel f ₂ (t _i ) and information about the radial speed of the additional antenna V _ra (t _i ). Based on these data, the calculator first calculates the value of the radial velocity of the radiation source V _r (t _i ) Li6o according to the formula

either by the formula

where i - 1, 2, 3 ... is the serial number of the azimuth and frequency measurement;

t _i is the time of the i-th measurement;

V _r (t _i ) is the radial velocity of the radiation sources at the i-th moment,

f _1,2 (t _i ) is the measured frequency of the signal in the direction finding / auxiliary / channel at the i-th point in time,

c is the speed of light;

V _ra (t _i ) is the radial speed of the additional antenna at the i-th moment.

направлен в сторону источника излучения, то V_ra больше нуля, а если

направлен от источника, то V_ra меньше нуля. Затем вычислитель из соотношенийMoreover, if the vector

directed towards the radiation source, then V _{ra is} greater than zero, and if

directed from the source, then V _{ra is} less than zero. Then the calculator from the relations

and

calculates the angular direction of the linear velocity vector / heading angle / at time t _i-2 β _к and γ _к - the angle of rotation of the linear velocity vector due to the curvature of the path of the radiation source over the time interval t _i-1 -t _i-2 . After that, the calculator according to the above formulas for r _i calculates the distance to the radiation source at any time of measurement, with the exception of the first and second measurements. Starting from the third dimension, i.e. From the third information retrieval, information from the calculator will receive information not only about the azimuth, but also about the distance to the radiation source. Synchronization of all processes for the calculation and removal of information is carried out by the control pulses of the synchronizer 11.

ни по модулю, ни по направлению мгновенно измениться не может. Это означает, что функция y=f(x), описывающая траекторию, - гладкая и непрерывная, а линейная скорость лежит в пределах от V_min до V_max. При этих условиях можно найти интервал времени Δ t, в течение которого можно считать

а изменение направления - плавное. На фиг.2 показана произвольная криволинейная траектория точечного тела М. Как известно, любую гладкую, непрерывную кривую можно аппроксимировать набором отрезков окружностей различных радиусов. На фиг.2 показана аппроксимация кривой М₀М дугами М₀М₁ радиуса R₁, М₁М₂ радиуса R₂, m₂m₃ радиуса R₃=∞ , М₃М₄ радиуса R₄, М₄М₅ - радиуса R₅ и M₅M радиуса R₆. Поэтому задача определения дальности от точки наблюдения до точки, лежащей на кривой ММ, по сути дела сводится к задаче определения дальности до точки, движущейся по окружности. Для этого необходимо всю кривую M₀М разбить на n участков и решать задачу нахождения дальности для каждого участка, считая, что на каждом к-том участке точка М движется по окружности радиуса R_к с постоянной линейной скоростью V_к.The validity of the calculation formulas V _r (t _i ) is protected by the USSR copyright certificate for the invention No. 776265, MKL G 01 S 11/00. The validity of the calculation formulas r _{i is} proved as follows. Let a point body M with a certain linear velocity V move in the HOA plane, with the origin at the point of observation, V. The trajectory of this movement is described by an unknown function y = f (x). In practice, an interesting case is when a point body imitates the movement of a man-made aircraft. In this case, it can be argued that the linear velocity vector

neither modulo nor direction can instantly change. This means that the function y = f (x) describing the trajectory is smooth and continuous, and the linear velocity lies in the range from V _min to V _max . Under these conditions, we can find the time interval Δ t, during which we can take

and the change in direction is smooth. Figure 2 shows an arbitrary curved trajectory of a point body M. As is known, any smooth, continuous curve can be approximated by a set of segments of circles of different radii. Figure 2 shows the approximation of the curve M ₀ M by arcs M ₀ M _{1 of} radius R ₁ , M ₁ M _{2 of} radius R ₂ , m ₂ m _{3 of} radius R ₃ = ∞, M ₃ M _{4 of} radius R ₄ , M ₄ M ₅ - radius R ₅ and M ₅ M radius R ₆ . Therefore, the task of determining the distance from the observation point to the point lying on the MM curve essentially reduces to the task of determining the distance to a point moving in a circle. For this, it is necessary to divide the entire curve M ₀ M into n sections and solve the problem of finding the range for each section, assuming that on each section the point M moves along a circle of radius R _k with a constant linear speed V _k .

Suppose that at any moment of time we can measure the radial component of the linear velocity V _r and the azimuth α to point M. Figure 3 shows the motion of point M on the k-th section of the trajectory. Point M _i-2 - the beginning of the k-th section, point M _i - the end of this section.

Suppose that at time t _i-2 , the radial velocity V _ri-2 and the azimuth α _{i-2 are} recorded. Restore the trajectory in one dimension, i.e. to find the range r _{i-2 is} not possible, because point M can be located anywhere on the azimuthal line α _i-2 and the pair V _ri-2 , α _i-2 will be fixed. Suppose that at time t _i-1 , the radial velocity V _ri-1 and the azimuth α _{i-1 are} recorded. From two dimensions, you can restore the trajectory, i.e. determine the range r _i-1 , only if the path is a straight line. Because if the trajectory is actually straight or curved, then a third measurement of the radial velocity and azimuth at time t _{i is} necessary. Then, using the set Vr _i-2 , α _i-2 , V _ri-1 , α _i-1 , V _ri α _i, you can restore the trajectory of the form of a circle of radius R _k centered at the point O _k , when moving along it with a speed V _k the above set of radial velocities and azimuths may form. Any other circle will give a different set, which is also shown in Fig.3.

Угол β _k отсчитывается от оси ОУ и положительный при отсчете против часовой стрелки. Обозначим через γ _k угол поворота радиуса R_k за время между первым и вторым измерениями. Угол γ _k - это по сути дела угол поворота вектора линейной скорости

за счет движения по кривой. При прямолинейном движении γ _k равен нулю.To solve the problem of determining the distance from the observation point to point M, we introduce the concept of the heading angle β _k at the first moment of measuring the radial velocity and azimuth on the k-th section of the trajectory. Heading angle is the angle between the axis of the op-amp and the linear velocity vector

The angle β _{k is} measured from the axis of the op-amp and is positive when counted counterclockwise. Denote by γ _{k the} angle of rotation of the radius R _k for the time between the first and second measurements. The angle γ _k is essentially the angle of rotation of the linear velocity vector

due to movement along a curve. In a rectilinear motion, γ _k is equal to zero.

In the first measurement, we do not know the linear velocity, but we can say that it lies in the range from V _min = V _r1 to some V _max · V _min = V _r1 will be in the case when α ₁ + β _k = 0.

Then

This means that the minimum value of β _k is equal to - α ₁ . The maximum value of the angle β _k can be found from the condition:

those.

Consequently,

thus,

By definition / cm. figure 3 /:

In these formulas and below, for ease of writing, i = 3, k = 1. We take the ratio of the radial velocities V _r2 and V _r1 and, given that on the k-th section, the velocity V _k = const, the equation of the radial velocity V _r3

From the relations / 1 / and / 2 / we find the values β ₁ and γ ₁ satisfying the measured values of V _r1 , α ₁ , V _r2 , α ₂ , V _r3 , α ₃ .

Note. The author deliberately does not give a methodology for finding β ₁ and γ ₁ , because not being a specialist in programming, I’m not sure whether it is easier to program a solution to the system of trigonometric equations, or to calculate the values of β ₁ and γ ₁ according to the formulas obtained as a result of the classical solution of the system of trigonometric equations / 1 / and / 2 /. These formulas are very cumbersome. The author is inclined to the method of successive approximation.

After determining the course angle β ₁ and the angle of rotation of the linear velocity vector γ _1, we can calculate the range value r ₃ . Indeed linear speed

Arc

But the arc

so

Chord

Angle

But

then

From the triangle OM ₂ M ₃ we have

where from

After measuring at the time t _{i + 1} = t _{4 the} azimuth α ₄ and the radial velocity V _r4 according to the same algorithm, we calculate for the segment k + 1 using the set V _r2 α ₂ ; V _r3 α ₃ ; V _r4 α ₄ . It turns out that the plot k + 1 is shifted relative to the plot number k by an angle γ _k , therefore, the selection of β _{k + 1} and γ _{k + 1} can begin with β _{k + 1} = β _k + γ _k . If it turns out that V _{r4 calculation is} greater than V _r4ism , then it is necessary to increase β _{k + 1} until V _{r4 calculation} becomes equal to V _r4ism .

If, when β _k and γ _{k are} found, γ _k = 0, this means that the trajectory turned out to be rectilinear in this section / there is no change in the linear velocity vector in the direction / and the calculation of the corresponding range must be carried out by the method for a rectilinear trajectory. In this case / cm. figure 4 /:

where q is the angle between the azimuth line and the linear velocity vector,

Δ α is the change in azimuth by time between two adjacent measurements of radial velocity and azimuth.

To simplify, we take i = 2. Since V = const, then

Solving the equality / 1 / relative to the angle q ₁ , and the equality / 2 / relative to the angle q ₂ , we find

In formulas 3 and 4, q _i are the exchange rate angles of the radiation source at the moments of azimuth and radial velocity measurements, counted from the direction of direction finding clockwise, Δ α is the difference in azimuths during the time between two measurements, and Δ α> 0 when the azimuth changes clockwise arrow and Δ α <0 when changing the bearing counterclockwise.

With allowance for the defining formulas for the radial velocity and heading angles, the linear velocity in a straight section of the trajectory can be found by the formulas

Consider the triangles EFA and ADV shown in Fig. 4. Both triangles are right-angled; therefore, from the ADV triangle, we have

But AB is the path traveled by the radiation source in the time Δ t, i.e.

Then

considering / 3 /

At the same time, from the EFA rectangle we have

Not OB - this is the distance from the observation point to a moving source of radio emission at the time of the second measurement of azimuth and radial velocity. therefore

where from

In the most general case

From all that has been said, it becomes clear that by making sequential measurements of the radial velocity and azimuth, it is possible, starting with the third measurement, to determine the distance to a moving source of radio emission in almost real time with a delay equal to the machine time for solving the problem using a computer. The algorithm is as follows. The current set of measurements of the radial velocity and azimuth of V _ri and α _{i is} taken, two sets of the previous ones / V _ri-1 , α _i-1 , V _ri-2 , α _i-2 /. According to these data from the ratios:

the angular direction of the vector is determined by the speed ruler / heading angle / at time t _i-2 , β _k and γ _k are the angle of rotation of the linear velocity vector due to the curvature of the trajectory over the time interval t _i-1 -t _i-2 . If γ _k turns out to be zero, then by the formula:

and for γ _k ≠ 0, then by the formula

the range to the moving radiation source at the current time is determined.

Claims (2)

1. A method for determining the coordinates of a moving radio source with unknown parameters, based on the reception, isolation and processing of the direct radiation signal from a radio source using a device containing an antenna, a receiver whose input is connected to the antenna output, an antenna control unit forming a direction finding channel, characterized in that at one receiving point, the direct radiation signal is successively received by the direction finding channel receiver, its frequency f _{1 is} measured, the azimuth α _{1 is} measured at the time of frequency measurement, and of the radio emission source, the signal is received by an additional receiver, the antenna of which is moved with a given radial speed V _ra relative to the antenna of the direction finding channel and the radio emission source, the frequency of the signal f ₂ received by the additional receiver is measured, according to the measurement results and the given radial speed of the mobile antenna according to one of the formulas

or

where V _r is the radial velocity of the source of radio emission at the time of measuring the frequency and azimuth; f ₁ is the frequency of the direct radiation signal received by the direction-finding channel receiver; f ₂ is the frequency of the signal of the same source of radio emission received by the receiver of the additional channel; V _ra is the given radial speed of the moving antenna; C is the speed of light equal to 299793000 m / s, at each moment of measuring the azimuth and frequency, calculate the value of the radial velocity of the source of radiation, the current set of azimuth α ₁ and the radial velocity of the source of radiation V _ri and the two previous sets of relations

determine the angular direction of the linear velocity vector of the radiation source at the first moment of measuring the azimuth and frequency β _k and the angle of rotation of the linear velocity vector of the radiation source for the time between the first and second measurements of azimuth and frequency γ _k , when the angle of rotation of the linear velocity vector γ _k is zero according to the formula

and when the angle of rotation of the linear velocity vector γ _{k is} not equal to zero by the formula

where r _i is the distance to the radiation source at the i-th moment of measuring the azimuth and frequency; i - 3, 4, 5 ... serial number of the measurement; V _ri is the radial velocity of the source of radiation at the i-th time; α _i - azimuth of the source of radio emission at the i-th moment of time; t _i - time of the i-th frequency and azimuth measurements; k = 1, 2, 3 ... is the serial number of the section of the trajectory of the radio emission source, the distance to which is currently determined; β _k is the angular direction of the linear velocity vector of the radiation source at the beginning of the k-th section of the trajectory; γ _k is the angle of rotation of the linear velocity vector during the time between the first and second measurements of azimuth and frequency in the kth section of the trajectory, calculate the distance to the source of radio emission at each moment of measuring the azimuth and frequency, with the exception of the first and second moments. 2. A device for determining the coordinates of a mobile source of radio emission and unknown parameters, containing a series-connected antenna and receiver, an antenna control unit forming a direction-finding channel, characterized in that an antenna is movable relative to the radio-source and direction-finding antenna, a receiver, a unit moving antenna control, two-channel frequency meter, calculator and synchronizer, and the output of the direction-finding channel receiver is connected to the first m input of the frequency meter, the output of the mobile antenna is connected to the input of the additional receiver, the output of which is connected to the second input of the frequency meter, the information outputs of the antenna control units, a two-channel frequency meter are connected to the corresponding information outputs of the calculator, the control outputs of the synchronizer are connected to the corresponding control inputs of the antenna control units , frequency meter and calculator.

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