RU2231806C2 - Method for estimation of current co-ordinates of source of radio emission - Google Patents

Abstract

FIELD: passive radio detection and ranging, applicable for determination of co-ordinates a radiating object according to the curvature of the wave-front with due account made for fluctuations of the signal phase in each receiving channel of the direction finder.

SUBSTANCE: the method consists in reception of the radio signal emitted by each element of an equidistant linear antenna array, amplification of it in each receiving channel, measurement of its frequency, normalization of signals with the aid of phase-meters proportional to the difference of signal phases in the central and each of the receiving channels, determination of the direction of signal input, reception of signals proportional to the difference of differences of phases symmetrical to the central and receiving channels, additional amplification of these signals, summation of the received signals, determination of the range to the source of emission, and performance of removal in pairs of the extreme elements of the equidistant linear antenna array, and approximate uniform arrangement of them in the longitudinal axis of the antenna array within the Fresnel zone of the non-removed elements, determination of the coordinate and the point of reference of the removed elements to the longitudinal axis of the antenna array, phasing of the channels, preliminarily determining the range to the source of emission with due account made of the values of the phase of the received signal at the removed elements, refinement of the co-ordinates and resolving of an ambiguity of range estimation on the basis of the algorithm of stochastic approximation.

EFFECT: expanded range and resolved ambiguity of measurement of the range to the source of radio emission at an equal quantity of the receiving channels.

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Description

The present invention relates to the field of passive radiolocation of ground, sea, air or space-based objects. It is designed to determine the coordinates of the emitting object from the curvature of the wavefront, taking into account fluctuations in the phase of the signal in each receiving channel of the direction finder.

Known methods for measuring coordinates by the active method [1]. The pulse method is based on measuring the delay time of the signal reflected from the target relative to the probing one. The disadvantage of this method is that it is impossible to measure short distances and requires a large pulsed radiation power. The frequency ranging method is based on measuring the magnitude of the change in the frequency of the transmitter during the delay time of the signal reflected from the target. This method allows you to measure small ranges to the target, uses low power. However, it requires the use of complex signals. With the phase measurement method, the range to the target is determined by the magnitude of the phase change of the modulating oscillations. The disadvantage of this method is the ambiguity of measuring range, the lack of resolution.

Known passive methods of measuring coordinates based on the use of the own radiation of objects [2]. Among them, the most widely used are triangulation, basocorrelation, as well as methods based on measuring the angles of arrival of a direct signal and reflected from the surface and other objects, and analysis of changes in the intensity of received signals with the subsequent calculation of the distance to emitting objects. The disadvantage of these methods of analogue range measurements is that they do not take into account the distortion of radar signals, leading to a deterioration in the accuracy of the measurement.

The closest in essence to the proposed method is a passive "method of measuring the distance to the radiation source" (Yastrebov Yu.V., Likhachev VP Application No. 95109676/09 (016808), positive decision of 04/15/97) [3], which consists in in that the radio signal emitted by the target is received by each i-th antenna, amplified in each i-th receiving channel, the signal frequency is measured, signals are generated using phase meters whose amplitudes are proportional to the phase difference (i is 0, 1, 2, ... , M / 2) signals of the i-th and central (i is 0) receiving channels, measure the sine of the angle at ode signal obtained signals proportional to the difference in phase differences symmetrical relative to the central receiving channels further amplify these signals i ² times, and summing them, and distance to the target is determined by the formula:

where L is the aperture size of the antenna (base), m;

s is the speed of light, m / s;

f is the frequency of the received signal, Hz;

γ _s is the angle between the direction of the radiation source and the aperture axis of the antenna, deg;

M + 1 - the number of antenna elements;

i is 0, ± 1, ± 2, ..., ± M / 2 is the serial number of the antenna element, and the numbers increase in magnitude from the central (zero) to the extreme (-M / 2 and M / 2), and the numbers symmetrical with respect to the central element of the antenna, differ in signs;

Δ φ _i = φ _i -φ _-i is the phase difference ix symmetric with respect to the central receiving channels;

φ ± _i is the phase difference of the signals received by the ± i-th and central antenna elements.

A device for implementing this known method contains (M + 1) identical antenna elements (AE) located relative to each other at a distance of half the wavelength λ _{0 of the} radiation source, (M + 1) identical receivers, M-phase meters, frequency counter, synchronizer, and the central (i is 0) AE is connected to the input of the corresponding receiver, the ith antenna element through the i-th receiver is connected to the input of the i-th phase meter, and the other input of each phase meter is connected to the output of the central zero receiver, which is through the frequency meter, the first phase meter and the synchronizer is connected respectively to the 1st, 2nd, 3rd inputs of the range calculation unit, the outputs of the M phase meters are connected respectively to the M inputs of the weight summing unit, the output of which is connected to the 4th input of the range calculation unit, and the output of the range calculation unit is the output of a range measuring device.

The prototype method and the device that implements it allow, taking into account the phase fluctuation in each receiving channel, to determine the distance to the radiation source located in the Fresnel zone. However, firstly, the practical implementation of the device corresponding to this method has severe structural limitations both in the number of receiving channels and in the geometric dimensions of the antenna array (AR) in almost any wavelength range. The restrictions imposed result in the fact that the upper limit of the range of range measurements by a device corresponding to the prototype method is much shorter than the range of various sources of radio emission in their functional purpose, for example, such as radar stations, communication, navigation and data transmission facilities. Secondly, the prototype method, like all phase ranging methods, is characterized by the ambiguity of its measurement, due to the possibility of changing the phase of the received signal by opening the AR by more than 2π.

The purpose of the invention is to expand the range and eliminate the ambiguity of measuring the distance to the source of radio emission with an equal number of receiving channels in devices that implement the proposed method and the prototype method. The goal is achieved by the fact that in the known method, which consists in receiving the emitted radio signal from each of the M + 1 elements of an equidistant linear AR located relative to each other at a half wavelength λ _{0 of the} radiation source, amplifying it in each receiving channel, measuring the frequency f received signal, the formation using phase meters of signals proportional to the phase difference of the signals in the central and each of the receiving channels, determining the direction of arrival of the signal γ _S1 , receiving signals proportional to of phase differences Δ φ symmetric with respect to the central receiving channels, additional amplification of these signals into the square of the serial number of symmetric channels times, summing the received signals and calculating by the formula of the distance to the radiation source, pairwise removal of N / 2 antenna elements from each edge of the AR (N many less than M) and their approximately uniform location on the longitudinal axis of the AR within the Fresnel zone ix undeployed elements (i is 0, 1, ..., (MN) / 2), determining the range and angular position of the remote ments, calculation of the measured coordinates of the points made by binding elements to a longitudinal axis AP (determination of their sequence numbers j _n), the phasing of the channels made by the AE, the preliminary score range ₁ to r of the radiation source with the received signal phase values for the elements made according to the formula

where c is the speed of light;

- база АР, образованной из (М+1) элементов,

- base AR formed from (M + 1) elements,

refinement of the coordinate vector R _{h =} {r _h , γ _sh } and the elimination of the ambiguity in determining the distance to the source of radio emission based on the stochastic approximation algorithm:

where μ = const;

- среднеквадратическая ошибка (СКО) оценки фазы при h-ой итерации поиска вектора R_h;

- standard error (RMS) of the phase estimate at the hth iteration of the search for the vector R _h ;

φ ' _{n (i)} and φ' _{n (i) h} are the real and calculated values of the phase difference in nx (ix) remote (non-remote) channels of the AR;

Δ R _h is a random increment of the vector R _{h =} {r _h , γ _sh } with average values of the parameters r _h and γ _sh equal to r ₁ and γ _s1 , and ranges of possible values Δ r ₁ and 3δ γ _s1, respectively, where:

r _dz = (M ') ² λ $\genfrac{}{}{0ex}{}{}{\text{0}}$ / 2 - the radius of the far zone for a three-element AR with the base L ';

q _s is the signal-to-noise ratio at the input of the receivers.

Thus, in the proposed method for determining coordinates, the following sequence of operations is performed:

1. Removal from each edge of the AP N / 2 (N is much smaller than M) AE at a distance ρ ± _n (n is 1, 2 ..., N / 2) from the central AE (i is 0) and their approximately uniform distribution on the longitudinal axis of the AR within the Fresnel zone of unexposed elements.

2. Determining the coordinates of the rendered elements.

3. Binding of the rendered elements to the central element of the AR (determination of the serial numbers of the rendered elements ± j _n ).

4. Reception and amplification of the received signal in each receiving channel.

5. Determining the frequency of the received signal, f.

6. The formation of voltages in M channels proportional to the phase difference in the i-th (n-th) and central (i is 0) channels, φ _{i (n)} .

7. A preliminary estimate of the angle of arrival of the signal γ _s1 .

8. Phasing of rendered elements relative to the central element of the AR.

9. Subtraction of signals in symmetric channels.

10. The amplification of the generated signals in each of the M + 1 channels by i ² (j _n ) ² times.

11. Summation of amplified signals.

12. A preliminary assessment of the distance to the radiation source, taking into account the phase values of the received signal on the remote elements.

13. Refinement of coordinates and elimination of the ambiguity of determining the distance to the source of radio emission based on the algorithm of stochastic approximation (random search).

New significant features of the invention are:

- Removal of N / 2 elements from each edge of the AR and their approximately uniform arrangement on the longitudinal axis of the AR within the Fresnel zone of undeployed elements.

- Determining the coordinates of the rendered elements.

- Binding of remote elements to the central element of the antenna system (determination of serial numbers ± j _{n of} remote elements).

- Phasing relative to the central AE of the channels of n-x and -n-x remote elements.

- A preliminary assessment of the distance to the radiation source, taking into account the phase values of the received signal on the remote elements.

- Refinement of coordinates and the elimination of the ambiguity of determining the distance to the source of radio emission based on the stochastic approximation algorithm.

The introduction of new significant features allows you to expand the range and eliminate the ambiguity of measuring the distance to the radiation source with an equal number of receiving channels in devices that implement the proposed method and the prototype method.

The invention is illustrated figure 1-5.

Figure 1 presents the set of operations that make up the essence of the proposed method, where it is indicated:

known operations: 4-7, 8-11;

newly entered operations: 1-3, 8, 12, 13.

On figa, b and c presents drawings explaining the process of determining the coordinates of the rendered elements and their phasing relative to the Central element of the AR, where indicated:

a) λ _0/2 - distance between the elements of the AP;

M + 1 - the total number of elements in the AR in the initial position;

N is the number of elements to be removed;

L = λ ₀ (MN) / 2 - the base of the AR, consisting of unexposed elements;

b) ρ ± _n is the distance between the phase centers of the central and

± n-th rendered element;

γ ± _n is the angular position of the elements;

± j _n = ± max | ± j ± _n | - anchor points of the n-th and -n-th taken to the longitudinal axis of the AP in the initial position;

Z _-n λ _0/2 - distance between the anchor point ± n-th element and pronounced central element AP;

c) γ _{s1 is the} direction of arrival of the signal from the radio source;

L ’is the base of the antenna system consisting of M + 1 elements after performing the phasing procedure of the removed elements.

Figure 3 presents an exemplary diagram of a device that implements the proposed method, where it is indicated:

1 - receiver;

2 - phase meter;

3 - frequency counter;

4 - clock generator (GSI);

5 - controlled phase shifter;

6 - block weight summation;

7 - a meter of the angle of arrival of the signal from the source of radio emission;

8 - block preliminary assessment of the range;

9 - phasing block of the remote elements;

10 - generator signal settings (GSI);

11 is a block for clarifying coordinates and eliminating the ambiguity of estimating the distance to the source of radio emission;

12 - antenna switch (AP).

Figure 4 presents a diagram of a block 6 weight summation of the difference of the phase differences, where indicated:

13 - converter of binary code into additional binary number code;

14 - memory buffer;

15 - storage device (memory) of coefficients i ² and j $\genfrac{}{}{0ex}{}{\text{2}}{\text{n}}$ ;

16 - adder of two numbers;

17 - a multiplier of two numbers;

18 - adder M numbers.

Figure 5 presents a variant of the construction of the device (figure 3) using a computer, where it is indicated:

19 - interface equipment;

20 - computers.

According to figure 1 (the numbering is made in accordance with the above listing), the entire process of determining the current coordinates of the source of radio emission is organizationally divided into three main stages. Initially, operations 1-3 of the preparatory stage are carried out, the essence of which is as follows.

Previously, from each edge of the AR, consisting of M + 1 antenna elements and similar to the prototype device (Fig. 2a), they are taken out at distances ρ ± _n from the central AE of N / 2 antenna elements (operation 1).

Moreover, the carried out elements are located approximately evenly on the longitudinal axis of the AR within the Fresnel zone of undeployed antenna elements [4]

ρ ± ₁ <ρ ± ₂ <... <ρ ± _{N / 2}

The range and angular position of the elements are determined. This task, for example, can be performed using the known method [3]. For the AR, the lattice is rotated ± 90 degrees in the direction of the remote elements (Fig.2b) and, alternately applying a tuning signal to them at a frequency f ₀ , the range ρ ± _n and the angular position γ ± _{n of the} remote elements are determined (operation 2)

where L is the base of the AR, consisting of (M-N + 1) not taken out elements;

φ ₁ is the phase difference between adjacent (central and first) unapproved elements of the AR when receiving the tuning signal from the ± n-th remote element.

[5].Expression (1) is transformed to the form (3) by replacing the product {...} with a finite sum of the degree of a natural number of the form

[5].

выражения (3, 4) упрощаются и принимают вид:Given that the distance between non-spaced elements of the AR is

expressions (3, 4) are simplified and take the form:

Given the absence of restrictions on the power of the tuning signal, the required accuracy of estimating the coordinates of n-elements is provided by the corresponding value of the signal (tuning) / noise ratio at the receiver input [6]:

Where

k = 2π / λ ₀ is the wave number;

I _i - gain of the i-th element of the direction finder;

q is the signal (tuning) / noise ratio at the receiver input;

ρ _i is the distance between the phase centers of the central and i-th unmatched AR element.

After determining the coordinates of the rendered elements, the APs are returned to their original position.

For certain values of ρ ± _n , the n-th elements are mapped to the central element of the AR (operation 3), which consists in determining the sequence numbers j ± _{n of the} removed elements. The numbers j ± _n correspond to an integer number of half-wavelengths of the tuning signal stacked at distances ρ ± _n and determine the inaccuracy of the symmetry of the nth and nth remote elements relative to the central one. The maximum of the pair of values of j _n and j _-n is the anchor point of the n-th and -n-th AE to the longitudinal axis of the AR in the initial position (fig.2b), located at a distance ρ _jn from the Central AE.

where Q ± _n is the remainder of the division of the left side of expression (8).

Next, operations 4–11 of the phasing of remote channels and preliminary estimates of the coordinates of the radiation source are performed.

If there is a signal from the radiation source, it is detected by each of the (M + 1) receiving channels (operation 4) and its carrier frequency f is determined (operation 5). Similarly to the prototype method, in the future, signals are generated that are proportional to the phase difference of the signals φ _{i (n)} in the channels of the i-th (n-th) and central AE (operation 6). Further, for example, similarly to [3], the phase method makes a preliminary assessment of the direction of the radiation source γ _s1 (operation 7)

where φ _s1 is the phase difference between the neighboring (central and first) unexploited elements of the AR when receiving a signal from a radiation source.

Given that, in practice, the nth and nth remote elements are located asymmetrically with respect to the central element of the AR, i.e. ρ _{n is} not equal to ρ _-n and γ _{n is} not equal to γ _-n (fig.2b), there is a need to perform the operation of phasing of the elements relative to the central (operation 8). This operation consists in calculating the phase additions Δ φ ± _n , the introduction of which into the receiving channels of the removed elements corresponds to their virtual movement to the points ± j _n on the longitudinal axis of the symmetrical relative to the central element in the initial position (Fig. 2c).

Then, the formation of signals proportional to the phase difference of the signals in the symmetric channels Δ φ _{i (n) is} performed (operation 9).

The received signals Δ φ _{(n) are} additionally amplified i ² (j _n ) ² times (operation 10) and summed (operation 11)

Based on the data obtained during the previous operations, a preliminary assessment of the distance to the source of radio emission (step 12) is carried out taking into account information about the phase values of the received signal on the remote elements:

where M '= 2max | j _n | ;

- база АР, образованной из (М+1) элементов.

- base AR formed from (M + 1) elements.

In this case, the range of unambiguous range measurement for three elements (two extreme remote and central antenna elements) of the antenna system is [4]:

where r _d.z = (M ') ² λ $\genfrac{}{}{0ex}{}{}{\text{0}}$ / 2 - the radius of the far zone for a three-element AR with base L '.

At the final stage, the procedure of refining the coordinates Rh = {r _h , γ _sh } is performed and the ambiguity of estimating the range to the source of the radio emission is performed (operation 13) based on the stochastic approximation algorithm [7-10]

- среднеквадратическая ошибка (СКО) оценки фазы при h-ой итерации поиска вектора R_h;Where

- standard error (RMS) of the phase estimate at the hth iteration of the search for the vector R _h ;

μ = const;

φ ' _{n (i)} and φ' _{n (i) h} are the real and calculated values of the phase difference in nx (ix) remote (non-remote) channels of the AR;

- отношение сигнал/шум соответственно.Δ R _h is a random increment of the vector R _h = {r _h , γ _sh } with the average values of the parameters r _h and γ _sh equal to r ₁ and γ _s1 , and the ranges of possible values Δ r ₁ (15) and

- signal to noise ratio, respectively.

Figure 3 shows an example of a device that implements the proposed method. This device operates as follows. Initially, from each edge of the AR consisting of M + 1 antenna elements mounted on a stabilized turntable [11], N / 2 extreme AEs are carried out and are uniformly installed, subject to condition (2), approximately on the longitudinal axis of the AR (operation 1). Next, the arrays are sequentially rotated ± 90 degrees in the direction of the remote elements and from the output of a highly stable generator (block 10), an tuning signal (CH) is supplied to the input of one of the n-antenna elements at a frequency f ₀ . The receiving channels of the remaining remote elements for the duration of the emission of the tuning signal are blocked by the antenna switch 12 (AP). Similarly to the operation of the device that implements the prototype method, in accordance with expressions (5, 6), the coordinates p ± _n and γ ± _{n of the} extracted element are determined, the values of which are digitized and stored in the memory of block 9 of the phasing of n channels. After determining in this way the coordinates of all the rendered elements (operation 2), the AR is returned to its original position. Block 9, in accordance with (8, 9), determines the anchor points (serial numbers ± j _n ) of each pair of remote elements (n-th and -n-th) to the longitudinal axis of the AP in the initial position (operation 3). By performing this operation, the stage of preparing the device for operation is completed.

In the presence of a radiation source, its signal is received by all antenna elements and enters the receivers (blocks 1). Each of the M + 1 receivers performs detection, i.e. selection against the background of internal noise and other interfering signals, amplification to a normalized level and digitization of the received signal with a binary code (operation 4). The signal from the high-frequency analog output of the central (zero) receiver is fed to the input of the frequency meter (block 3), which measures the frequency f of the received signal and converts its value into a binary code (step 5). Further, the received signals are fed to the phase meters (blocks 2). Each of the M phase meters that determine the degree of correlation of the two signals [12] generates a binary code proportional to the phase difference φ ± _{i (n)} between the signals from the outputs ± i-th (± n-th) and central (i is 0) receivers ( operation 6). The phase difference signals φ ± _i , and φ ± _n then go to the memory buffers 14 (figure 4) of the weight summing unit 6 and phase shifters 5, respectively. The signal from the output of the first phase meter, in addition to block 6, is input to the angle meter (block 7), which, according to the phase difference φ _s1 in accordance with (10), determines the preliminary value of the sine of the angle of arrival of the signal γ _s1 and translates it into binary code (operation 7). Based on the data on the coordinates of the elements removed and information on the direction of arrival of the signal γ _s1, the phase addition Δφ ± _{n is} calculated in accordance with (11). The signals of the phase additions Δ φ ± _n in binary code are fed to the control inputs of the phase shifters 5. Phase shifters made, for example, based on digital adders [12, 13], in accordance with (11), generate binary discrete φ ± _n '(operation 8 ), which are fed to the corresponding inputs of block 6 weight summation. Simultaneously with the formation of the signals Δφ ± _{n by} the phasing unit 9, a sync pulse (SI) is generated, which triggers a clock generator 4 (GSI). Block 4 controls the processes of summation and multiplication in the device (WU).

поступающая на вход блока 8 (фиг.3) предварительной оценки дальности. Блок 8 в соответствии с (14) осуществляет предверительное определение значения дальности до источника r₁ (операция 12), которое наряду с информацией о его угловом положении γ _s1 в качестве исходных данных поступает в блок 11 (фиг.3) уточнения координат и устранения неоднозначности оценки дальности.Block 6 weight summation (figure 4), made, for example, on the basis of arithmetic logic devices, code converter 13 converts binary information about the values of φ _{-i (n)} into an additional binary number code [12] and using adders 16 forms discrete modules | Δ φ _{i (n)} | = | φ _{i (n)} -φ _{-i (-n)} | (operation 9), additionally by multipliers 17 amplifies the received signals in i ² (j $\genfrac{}{}{0ex}{}{\text{2}}{\text{n}}$ ) times (operation 10) and summarizes them (operation 11). As a result of operations 9-11, a discrete is formed at the output of the adder M numbers 18 of the weight summation block 6

arriving at the input of block 8 (Fig. 3) of a preliminary range estimate. Block 8 in accordance with (14) carries out a preliminary determination of the value of the distance to the source r ₁ (operation 12), which, along with information about its angular position γ _s1 , enters the block 11 (figure 3) for updating coordinates and eliminating ambiguity as initial data range estimates.

Block 11, based on the stochastic approximation algorithm (16), performs the final procedure for refining the coordinates of the radiation source and eliminating the possible ambiguity in estimating the distance to it (operation 13). The output of block 11 is the output of the device. If necessary, several samples R = {r, γ _s } can be used to determine the derivatives of these coordinates.

The design of the proposed device is based on the use of known elements and does not present technical difficulties.

Obviously, the invention is not limited to the above-described example of its implementation. Based on it, other options may be provided, for example, using a computer (figure 5). In this case, the high-frequency part of the device remains unchanged, and the digital information about the received signal from the outputs of the receivers 1 through the interface equipment 19, which performs the matching function, goes directly to the computer 20. Then, operations 1, 2 (in terms of using the settings generator 10), 4 and 5 is carried out similarly, and operations 2 (in terms of calculating the coordinates of the rendered elements) 3, 6-13 are implemented using the appropriate computer software.

Assessment of the feasibility and effectiveness of the proposed method was carried out by mathematical methods of computer simulation. Operations 4-7, 9-11 are known, their implementation is similar to the prototype and is beyond doubt [1, 3, 4, 6].

Operation 1 is performed by mechanically moving N removable antenna elements together with the receivers and arranging them approximately uniformly, subject to condition (2) on the longitudinal axis of the AR in the initial position. The joint movement of the AE and the receivers is carried out in order to maintain the identity of the phase distortion values introduced by the antenna-feeder paths [14] in all receiving channels and does not cause special difficulties.

The implementation of operation 2 is carried out by alternating radiation by the antenna elements of the tuning signal at a frequency f ₀ and determining their coordinates in accordance with the prototype method [3]. The required accuracy of the estimation coordinates n-th elements (phase center) determined by the error location Failure to Render AE phase centers on the longitudinal axis AR every λ _0/2 and provides a corresponding output signal for this [4, 6], the settings of the generator.

Operations 3 and 8 for linking the removed elements to the longitudinal axis of the AR (determining their serial numbers) and their phasing are calculated and can be implemented using a computer.

The possibility of implementing operation 4 was evaluated by the radio intelligence formula [15].

When calculating the following were taken:

equivalent sensitivity of the receivers - 130 dB / W, equivalent pulse power of the radiation source - 40 dB / W, wavelength of the radiation source λ $\genfrac{}{}{0ex}{}{}{\text{0}}$ - 0.1 m, the coefficients of the mismatch between polarization and losses in the antenna-feeder path - 0.5, the threshold signal-to-noise ratio at the input of the receivers is 7 dB, the passband of the receiver and the spectrum width of the emitted signal are matched, the observation conditions correspond to line of sight.

For the above conditions, the range of reconnaissance of the signal of the radio source R _rtr is 300 km.

учитывающих значения весовых коэффициентов и фазы принимаемого сигнала на вынесенных элементах после выполнения операций их привязки и фазирования. Такой подход позволяет аналогично прототипу производить оценку дальности с учетом флюктуации фазы сигнала во всех приемных каналах и соответствует случаю определения дальности по кривизне волнового фронта симметричной разреженной антенной решеткой [4].Expression (14) according to a preliminary estimate of the range (operation 12) is obtained from expression (3) by adding additional terms

taking into account the values of the weighting coefficients and the phase of the received signal on the remote elements after the operations of their binding and phasing. This approach allows, similarly to the prototype, to evaluate the range taking into account the phase fluctuation of the signal in all receiving channels and corresponds to the case of determining the distance from the curvature of the wave front by a symmetrical sparse antenna array [4].

The procedure for updating the coordinates and eliminating the ambiguity of estimating the distance to the source (operation 13) is based on the stochastic approximation algorithm (16), which is quite well known in the theory of adaptive antenna arrays and extremal control [7-10]. Under conditions of possible multi-extremeness of the evaluated function (ambiguous correspondence of the phase of the received signal of the range to the source and its angular position), the use of this particular algorithm is most preferable in relation to other adaptation algorithms (gradient, direct inversion of the sample covariance matrix, recurrent and cascading, etc. ) Its use during the execution of procedure 13 allows the most efficient method to unequivocally find the global extremum (eliminate ambiguity) of the estimated function, when practically nothing is known about the nature of its behavior [7-10].

After performing operation 13, the potential accuracy of estimating the angular position and the distance to the radiation source by a symmetrical sparse antenna array is achieved [4, 6]

Where

The implementation of algorithm 16 is carried out on a computer and does not cause any particular difficulties.

If it is necessary to calculate the radial V _r and tangential Vτ velocities of the carrier of the radiation source, operations (4-13) are repeated after a time interval Δ t. As a result of this, the change in the distance ± Δ r and the angular position ± Δ γ _s between the phase centers of the antennas of the radiation source and the AR corresponding to the interval Δ t is estimated. Then, assuming that the motion of the carrier of the radiation source is straightforward,

Mathematical calculations showed that the proposed method provides a wider range of measurement of the distance to the radiation source with an equal number of identical receiving channels in devices that implement this method and the prototype method. So, for example, assuming the distance between AEs to be 0.05 m (λ is 0.1 m) and the number of receiving channels (M + 1) in the proposed device and prototype device equal to 61, we obtain, in accordance with [4], the following ranges determining the range to the radiation source (the boundaries of the Fresnel zone):

a) The method and device prototype.

Near Radius

Far radius

Range of measured range

b) The proposed method and device.

Assuming the total number of carried-out antenna elements N equal to 10, we determine the boundaries of the Fresnel zone for an AR consisting of unexploited elements (AP1)

We assume the operations of removal, determination of coordinates, binding and phasing of the nth elements are performed so that their phase centers are located uniformly within the Fresnel zone AP1 and symmetrically with respect to its central element. In this case, the maximum L ’AR base, consisting of M + 1 antenna elements, is 250 m. Then the potential range of measured ranges is:

Thus, the proposed method potentially allows you to increase the range of the measured range in comparison with the prototype more than 7 thousand times and achieve the potential accuracy of estimating the coordinates of the radiation source (17).

By limiting the upper boundary of the range of the measured range by the range of electronic reconnaissance R _rtr for the above conditions, we can determine the required dimensions L _tr AR (maximum distance of the removal of n-antenna elements).

For such AR sizes, the lower limit of the measured range is 2.7 km.

If the radiation source approaches the lower boundary of the measured range, further tracking of the target in range is possible. To this end, a sequential exclusion from the processing of channels of extreme remote elements is made, which corresponds to a sequential decrease in the geometric dimensions (base) of the AR, and therefore the lower limit of the measured range.

Thus, the aim of the invention is to expand the range and eliminate the ambiguity of measuring the distance to the source of radio emission with an equal number of receiving channels in devices that implement the proposed method and the prototype method is achieved.

Literature

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Claims (1)

A method for evaluating the current coordinates of a radio source, which consists in receiving the emitted radio signal from each of the M + 1 elements of an equidistant linear antenna array (AR) located relative to each other at a half wavelength λ _{0 of the} radiation source, amplifying it in each receiving channel, measuring the frequency f of the received signal, the formation using phase meters of signals proportional to the phase difference of the signals in the central and each of the receiving channels, determining the direction of arrival of the signal γ _s1 , receiving signals proportional to the phase difference Δ φ symmetric with respect to the central receiving channels, additionally amplifying these signals into the square of the sequence number of the symmetric channels times, summing the received signals and calculating by the formula of the distance to the radiation source, characterized in that they carry out pairwise removal from each edge of the AP N / 2 antenna elements, where N is much smaller than M, and they are approximately uniformly placed on the longitudinal axis of the AR within the Fresnel zone ix unexploited elements, where i = 0, 1, ..., (MN) / 2, defined dividing the range and angular position of the removed elements, calculated from the measured coordinates of the anchor point of the removed elements to the longitudinal axis of the AR and thus determine their serial numbers j _n , phasing the channels of the n remote antenna elements, where n = 0, 1, ... , N / 2, preliminary estimate the range r ₁ to the radiation source, taking into account the phase values of the received signal on the remote elements according to the formula

where c is the speed of light; M '= 2max | j _n | ; Δ φ _i = φ _i -φ _-i and Δ φ _n = φ _n -φ _-n are the difference of the phase differences ix and n-symmetric with respect to the central receiving channels, respectively; φ ± _i and φ ± _n - phase difference of the signals received ± i-th and ± n-th and central antenna elements, respectively;

- the base of the AR formed from (M + 1) elements, specify the coordinate vector R _h = {r _h , γ _sh } and eliminate the ambiguity of determining the distance to the source of radio emission based on the stochastic approximation algorithm

where μ = const;

- the standard error (RMS) of the phase estimate during the hth iteration of the search for the vector R _h ; φ ' _{n (i)} and φ' _{n (i) h} are the real and calculated values of the phase difference in the n-th (ix) remote (non-remote) channels of the AR; Δ R _h is a random increment of the vector R _h = {r _h , γ _sh } with average values of the parameters r _h and γ _sh equal to r ₁ and γ _s1 and ranges of possible values Δ r ₁ and 3δ γ _s1 , respectively;

r _ds = (M ') ² λ _0/2 - radius of the far zone for the three components with AP base L';

q _S is the signal-to-noise ratio.

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