RU2354994C1 - Method of processing information in coherent laser locator with photodetector array - Google Patents

Abstract

FIELD: physics; measurement.

SUBSTANCE: present invention relates to measuring techniques and instrument making and can be used in laser Doppler location of stealth objects flying at low altitudes above water basins. The method of processing information in a coherent laser locator with a photodetector array is based on reception of laser radiation from glare of the sea surface, arising when probing radiation is scattered by the stealth object. The current location of an object and its velocity vector can be reconstructed through measurement of angle of arrival of radiation from the glare of the sea surface using a photosensitive reception matrix and through measurement of Doppler frequency shifts in a multi-channel unit for optimum filtration based on heterodyne reception methods using multi-channel dispersive delay lines using statistical averaging methods. Cutting on the number of information processing units is achieved due to creation of two- or three-dimensional groups of elements of a photodetector array, connected to information processing channels. In the processing channel, the signal is converted to a linear-frequency-modulated equivalent with subsequent amplification, spectro-time "compression" in the dispersive delay line, detection and minimum threshold cutting with a given threshold value, which allows for converting a signal with Doppler frequency shift to a short pulse, the time position of which, relative the strobe-pulse for the beginning of the measuring cycle, uniquely characterises the value of the given Doppler frequency shift. This time position of the pulse is coded in a digital code and stored in the corresponding buffer memory of a memory device, in the code of which there is also a code of the number of the measurement cycle and the code of the number of the channel, on which the signal from an element of the photodetector array was processed. From the set of such code records in the given measurement cycle, information is obtained on Doppler frequency shifts in signals of corresponding elements of the array and the position angle on the glare of the sea surface, detected by the locator in the given measuring cycle relative the optical axis of the receiving-transmitting objective of the locator, as well as scatter angles of the probing radiation of the stealth object, generating the said glares. If conditions are met for detecting an object and its bearing auto-tracking, where the inclined range line and the optical axis of the receiving-transmitting objective of the locator lie in the same plane, location of the object and measurement of its radial velocity is done through calculation, using a minimum of two different reflected radiation in a given measurement cycle, based on the method of overlapping circles. The radiation pattern of the locator is fan-shaped - wide on the position angle and extremely narrow on the azimuth.

EFFECT: simplification of the design of the device implementing the method, particularly the design of the information processing unit with dispersive delay lines, as well as possibility of locating stealth objects without reception of radiation directly from the located object in its probing direction.

7 cl, 11 dwg

Description

The invention relates to the field of measuring equipment and instrumentation and can be used in laser Doppler location of low-flying “invisible objects” (cruise missiles, aircraft like Stels, etc.) flying low above water pools.

On September 11, 2007, Central Television reported in detail on the development in the USA of an invisible aircraft under the Stels project, which was used by a military company in Iraq and the appearance of which could not be detected by cross-border air defense systems due to the special form of this aircraft. This form, in violation of the laws of aerodynamics, allowed us to significantly reduce the effective reflection surface (EPO) of the probing radio emission of air defense radars and was a mirror-reflecting face of the hull located at angles to the incident radiation, which led to the reflection of the latter in directions that did not substantially coincide with the direction of incident on the plane radar radiation (mainly down and up relative to the motion vector of the aircraft). The shape of the invisible plane resembled that of an arrow. One of our scientists, F. Ufimtsev, developed the theory of electromagnetic wave diffraction for such objects and collaborated in the United States in the process of creating the Stels project, but also proposed a method for detecting stealth aircraft, the essence of which was the use of several radar receiving devices dispersed in space relative to the air defense radar, with the help of which it is possible to receive radar radiation scattered reflected from an invisible aircraft. However, this method is expressed in the form of the idea of possible detection, without a specific indication of the technical means of implementing the method and the composition of the equipment.

When using this hypothetical method for detecting moving invisible objects with very small EPO values as applied to the tasks of the Navy, that is, under conditions of work at sea (in the ocean), difficult obstacles arise due to the need for mutual topographic reference of a group of ships with the indicated radar receivers dispersed reflected radar radiation, also located on one of the ships of this group in motion. This circumstance impedes the implementation of the idea of F. Ufimtsev in relation to the laser coherent location of cruise missiles or invisible aircraft flying low over water basins, the detection of which and the measurement of their coordinates and speed must be carried out in advance.

It is known to construct laser Doppler locators with multichannel information processing based on dispersive delay lines (DLD) operating in the mode of heterodyne reception of radiation [1-7]. Using the factor of high coherence of radiation of single-frequency gas lasers [8, 9], for example, CO ₂ lasers, it is possible to coherently receive such emissions by the method of mixing the signal and heterodyne beams, which is used in laser Doppler locators. The difference-frequency radio signals obtained as a result of photo-mixing are processed in matched filters at DLZ, which makes it possible to increase the detecting ability of locators, that is, the value of the signal-to-noise ratio at the input of the resolver [10-15]. It should be noted that in such locators the transmission path does not include radiation modulating devices (for example, electro-optical modulators), as is the case with laser pulse locators, which provides a higher energy potential of Doppler locators compared to pulse systems per unit of useful energy (or average power) laser radiation.

To detect objects in the extended elevation zone Δε of a circular view with a narrow instantaneous angle of view in the azimuth Δφ (that is, with a "fan-shaped" radiation pattern) in coherent radars on CO ₂ lasers, photodiode arrays of N photosensitive KRT elements (triple compounds Kd Hg Tl cooled by liquid nitrogen) with N-channel matched filtering using DLZ. In this case, the limiting oblique range d for detecting diffuse diffraction-limited objects is found from the solution of the transcendental equation

where ζ - extinction medium P - power of the emitting laser, k _t - transmittance in emitting and receiving paths, y _^ - efficiency photomixing, S - effective surface reflection (EPO) of located object, D - diameter of the entrance pupil (receiving lens), μ is the signal-to-noise ratio by voltage at the input of the deciding device, γ is the spectral density of the noise power of the photodetector (photosensitive element КРТ), Т ₀ is the period of all-round viewing, B = τΔF is the base of the DLP, τ is the duration of the pulse characteristic of the DLZ, ΔF is the working band DLZ frequencies, ΔF _Σ - bands and the uncertainties of Doppler frequency shifts ΔF _Σ = 2Δv / λ, where Δv is the difference between the highest and lowest possible radial velocities of a moving object, λ is the laser radiation wavelength (λ = 10.6 μm for a CO ₂ laser), and for a Gaussian signal and noise we have μ ² = (InФ / InG) -1, where G and Ф are, respectively, the probabilities of correct detection and false alarms, the values of which are usually set when calculating a location system.

The choice of DLZ significantly affects the detection, accuracy and dynamic characteristics of the locator, as follows from (1). The threshold properties of the photodetector for coherent reception are determined by the parameters γ and у _ф .

The resolution of the contradictions between the increase in the energy potential of the locator (the limiting detection range of a small target) and the simplification of the procedure for measuring the main characteristics of the located objects — their flight altitude, slant range and velocity vector (including the radial velocity parameter) is achieved using the location method known from the RF patent No. 2296350 (published in Bulletin No. 9 of 03/27/2007) by the same author, which can be used as a prototype of the claimed technical solution.

The known method is based on the use of a combination of the Doppler principle of location with the triangulation method of target determination. The latter is achieved through the use of glare reflected from the target at different angles of radiation from the sea surface, the radiation from which comes to the locator at different measured angles and with Doppler frequency shifts as a function of the reflection angles of the incident radiation from the target surface of the target. By measuring the angles of arrival of radiation from the glare of the sea surface by a photosensitive receiving matrix and by measuring the values of Doppler frequency shifts in a multi-channel block of optimal filtering based on heterodyne reception methods using multi-channel dispersion delay lines, statistical averaging can reconstruct the current location of the target and its velocity vector.

The specified location method is based on sensing a diffraction-limited object moving above the surface of the sea (ocean), unmodulated emissions from a single-frequency continuous laser and multichannel coherent processing of received radiation by a matrix photodetector with the determination of Doppler frequency shifts in re-reflected radiation and subsequent multichannel parallel matched filtering and extracted radio signals characterized in that the coherent reception and processing of additional o and at the same time, the radiation reflected from several glare of the sea surface arriving at the photodetector matrix from different randomly distributed angular directions is determined in the corresponding channels associated with the matrix photodetector device, Doppler frequency shifts in the received radiation for signals reflected from the glare of the sea surface and their corresponding angular coordinates for these glare, calculate the current coordinates of the location of the object and its true speed, as well as statistically dnyayut computation results of the totality of joint measurements of the above parameters.

The prototype method assumes that the measured Doppler frequency offset _Δυ additional ₀ = 2vυ ₀ / s = 2v / λ of the probing radiation in the signal directly reflected from the positioned object and the angles ε ₀ and φ ₀ at which the radar "sees" this object directly (angles location of the oblique range line), where v is the radial velocity of the object, υ ₀ is the frequency of the probe laser radiation. However, in the case of the location of moving invisible objects, the measurement of the direct reflected signal is considered impossible, and the location is carried out only by the totality of glare reflections from the sea surface when the probe radiation is scattered down-sided from the location object. This uses a different procedure than the one stated in the prototype method, the processing of the received glare radiation.

The optimal energy potential solution in the prototype method is the use of a multi-channel information processing path based on DLA with the number of channels equal to the number of elements of the photosensitive matrix N _E. At the same time, the drawbacks of this solution are the increased amount of equipment, since the requirement to increase the resolution in angular coordinates, which determines the accuracy of the locator by determining the current coordinates and speed of the location object, leads to the use in the locator of a photodetector with a very large number of elements along rows and columns, for example matrices with a size of 100 × 100 elements or more.

Another disadvantage of the known method is the need to ensure the reception of direct radiation reflected from the object location, that is, in the direction of sounding, which is not always possible, for example, when the location of the invisible object.

These disadvantages of the known technical solutions for the prototype method are eliminated in the claimed method.

The aim of the invention is to significantly simplify the device implementing the claimed method, in particular, the design of the information processing unit with remote sensing data, by reducing by more than one or two orders of the number of signal processing channels generated in the elements of the matrix photodetector.

Another objective of the invention is to enable the location of invisible objects when there is no reception of radiation directly from the location object in the direction of its sounding.

The inventive method can be characterized by one main and several dependent claims.

1. A method of processing information in a laser coherent locator with a matrix photodetector based on measuring Doppler frequency shifts Δυ _DOPi in emissions from sea glare and the angular coordinates of the latter - azimuths φ _i and elevation angles ε _i , calculating the coordinates of the location object and its speed with subsequent statistical averaging the calculated parameters for several adjacent measurement cycles, characterized in that N _e = ^kp p matrix photodetector elements form two independent outputs that form a two-dimensional (p = 2) or dimensional, (p = 3) group, where k = 1, 2, 3, ... - are integers with n = 2p ^k (p-1) output lines in groups to each of the output bus group in parallel connected by r = p ^k the corresponding outputs of the row or column elements of the matrix photodetector, and the calculation of the coordinates of the location object according to the measured Doppler frequency shifts Δυ _{DOP i} with the corresponding measured angular coordinates - azimuth φ _i and elevation angle ε _i to the corresponding α _i glare of the sea surface visible by the locator in this measurement cycle, where i = 1, 2, 3, ... m is the number of valid x flare radiation, carried out by sequential iteration of unknown parameters - the radial velocity v of the location object in the a priori expected interval of its permissible change and elevation angle ε _{0 of} the oblique range line to the location object, for which, in the course of the indicated iterative selection of these parameters, their values of v and ε ₀ at which the differences between any pairs of quantities that determine the slant range to the location object are minimized.

2. The method according to claim 1, characterized in that the resulting uncertainty of the choice of 2 (p-1) output buses corresponding to the same Doppler frequency shift Δυ _{ADD i} in the signal at the outputs of the element α _{jk of the} photodetector, according to the position of which in the matrix judge the azimuth φ _i and elevation angle ε _i to the visible sea glare α _i , eliminate it by comparing the codes displaying Doppler frequency shifts by their 2 (p-1) -fold coincidence for all m sea glare with a given minimum error.

3. The method according to claim 1, characterized in that the calculation of the measured parameters of the location object with a large amount of computational operations associated with the iteration process when searching for values of v and ε ₀ that satisfy the specified condition is performed in a time interval exceeding the specified measurement cycle, and then relate the results to the point in time of the initial measurement cycle.

4. The method according to claim 1, characterized in that the reduction in the volume of computational operations during the iterative search of the values of v and ε ₀ in each subsequent measurement cycle is achieved by reducing the interval of their iterative search, taking into account data on these values from previous measurement cycles and taking into account the statistical averaging each of these values over several successive measurement cycles on the assumption that the values found and ε ₀ v are slowly varying functions of time in comparison with a predetermined repetition cycle rate and dimensional.

, и при этом минимизируется абсолютная величина разности любых двух значений х_i с разными индексами i из их числа m.5. The method according to claim 1, characterized in that the coordinates of the located object are refined by performing an iterative search of the values of v and ε _{0 by} jointly solving the system of m equations x _i = f (h ₀ , ε ₀ , φ _i , ε _i , v) for all sea glare visible by the m locator, that is, for i = 1, 2, 3, ... m, where the scattering angle of the probe radiation relative to the direction of the latter is Θ _i = arccos (Δυ _{ADD i} * λ / 2v), λ is the wavelength laser, h ₀ - known height above sea level of the center point of the receiving lens locator, so that the x-coordinate is calculated by formula is

, and the absolute value of the difference between any two values of x _i with different indices i from their number m is minimized.

6. The method according to claim 1, characterized in that the detection of the location object and its auto-tracking is carried out by scanning the probe radiation in azimuth, and the radiation pattern is chosen fan-shaped - extremely narrow in azimuth and wide in elevation.

7. The method according to claim 1, characterized in that when the conditions for detecting the location object and its auto tracking in azimuth are fulfilled, in which the oblique range line and the optical axis of the locator transmitting lens lie in one plane, the location of the location object and the measurement of its radial speed found by calculation, minimum for two different flare radiations (Min m = 2) in a given measurement cycle.

Achieving these goals is due to the use of a triangulation method for locating an object, the implementation of which with one locator is explained by the reception of glare radiation dispersed on the sea surface, generated by irradiating the sea surface, which is a stochastically distributed set of mirror reflectors, by laser radiation scattered at different angles relative to the sounding direction of the location object body. Depending on the angle of such scattering in the received flare radiation, the Doppler frequency shifts respectively change. The spatial position of the glare is unambiguously measured by the azimuth φ _i and the elevation angle ε _i at the ith flare at a known height h ₀ and the corresponding topographic location of the locator. According to the Doppler frequency shifts Δυ _{DOP i} for the corresponding sea glare and the measured angular coordinates of the oblique range line to the object φ ₀ and ε ₀ and the radial velocity v of the latter, the corresponding angles η _{i are} reconstructed at which the radiation scattered by it can come from the object. These corners form a conical surface. Two such glare radiations are used to construct two such surfaces, the intersection of which forms a curve on which the object’s body point is located, from which the scattered radiation emanates. The use of the third conical surface when considering the third sea flare forms three indicated curves, respectively, forming at the intersection points of the vertices of the curved triangle, inside which there is an interesting point on the body of the object. If the values of v and ε _{0 are} chosen correctly by successive iterations, the area of such a curved triangle is minimized: in the limit, such a triangle is contracted to the desired point. The indicated geometric interpretation of the procedure for finding body points from which scattered radiation emanates and which determine the coordinates of a location object, which, in turn, is considered diffraction limited, point with respect to the locator, is realized by studying the minimum differences of analytically calculated segments x _i (i projection on the x-axis of the inclined range line onto the location object) for different indices i for m glare in each measurement cycle, since such minima correspond to the minimum distances m between the vertices of these curved triangles, that is, the minimum area of the latter.

Two-dimensional or three-dimensional connection of the matrix photodetector elements to information processing channels using the conversion of the signal received from one or another matrix element into a linear-frequency-modulated (LFM) equivalent, followed by its amplification, spectro-temporal “compression” in channel dispersion delay lines (DLZ) ), detection and threshold limitation at a minimum with a given threshold limit allows you to convert the signal with a Doppler frequency offset into a short pulse, the temporary position to relatively to the strobe pulse, the beginning of the measurement cycle uniquely characterizes the magnitude of the indicated Doppler frequency shift. This temporary position is encoded in a digital code and stored in the corresponding buffer memory (CCD), the code of which also contains the code of the number of the measurement cycle and the code of the channel number, which was used to process the signal from the photodetector matrix element. This makes it possible to reconstruct uniquely two parameters from the totality of such code entries in this measurement cycle — the Doppler frequency shift Δυ ADP _i for the signal from the output of the corresponding matrix element and its location in it. The latter, in turn, uniquely determines the azimuth φ _i and elevation angle ε _i on the highlight of the sea surface α _i , which is visible by the locator in this measurement cycle relative to the optical axis (probe axis) of the transmitting and receiving lens of the locator (it is assumed that the central element matrix photodetector aligned with the specified optical axis).

The indicated method of connecting elements of the photodetector matrix to information processing channels significantly reduces the number of such channels, that is, simplifies the design of the device implementing the claimed method, however, it leads to ambiguity in the correct calculation of data about the location object, which is eliminated by comparing codes corresponding to the measured Doppler frequency shifts from different glare sea surface, assuming that Doppler shifts are different from different glare. Moreover, the choice of two-dimensional p = 2 or three-dimensional p = 3 representations of groups is determined opportunistically. With two-dimensional organization of a group, the volume of computational operations is significantly reduced, but the required number of channels with DLP is growing, and with three-dimensional organization, the number of channels with DLP is decreasing, but the volume of computational operations is slightly increased due to increased uncertainty, especially with a large (more than three) number m at the same time processed emissions from glare of the sea surface in this measurement cycle.

In the drawings presented, individual provisions are disclosed that reveal the essence of the claimed technical solution.

Figure 1 shows the organization of a two-dimensional group (p = 2) of N _E = p ^2k elements of the photodetector 1, the elements of which α _jk (for the jth row and kth column) are organized into a square matrix with a side in p ^k elements. The number of output buses of assemblies 2 and 3 in this case is n = 2р ^k = 2 ^{k + 1} . With this organization, the elements of the photodetector matrix have two independent signal outputs. With a relatively small number of elements N _{E, it is} preferable to use a two-dimensional organization of the group. So, with a 32 × 32 element matrix, the number of channels is n = 64 instead of 1024.

Figure 2 shows the organization of a three-dimensional group (p = 3) of N _E = p ^3k elements α _jk , which is a cube of elements 4 with a side of such a cube p = 3 elements. Each of two mutually orthogonal faces of such a cube represents two-dimensional structures 5 and 6 with the number of tires in each of p ^2k = 3 ^2k . Each such two-dimensional structure defines, respectively, a pair of assemblies 7 and 8, 9 and 10 of the output buses. In this case, the total number of output buses is n = 2p ^k (p-1) = 4 * 3 ^k . With this organization, the elements 11 of the photodetector array 12 (physically flat design) have two independent signal outputs, and 3 ^2k buses of each of the two-dimensional structures 5 and 6 are connected to the output buses of assemblies 7-10 through intermediate amplifiers 13 with two independent outputs each. With a large number of elements N _{E, the} three-dimensional organization of the group may be more preferable. So, with a matrix dimension of 729 × 243 = 19683 = 3 ⁹ elements, that is, with k = 3, the number of processing channels is n = 108 instead of 19683.

Figure 3 presents one typical channel for processing the signal from the output bus for the corresponding two-dimensional or three-dimensional group. The channel contains a series-connected mixer 14, a first broadband amplifier 15, a dispersion delay line (DLS) 16, a second broadband amplifier 17 that compensates for signal loss in the DLS, an amplitude detector 18, a minimum limiter 19 with a given threshold threshold, and a comparator 20. For all n The processing channels use a common linear frequency-modulated oscillation (HLF) generator 21, the input of which is triggered by a strobe pulse generator (GSI) 22, and the output of the HLF is connected to the second inputs of the channel mixers 14. The time delay between the moments of the appearance of the strobe pulse that opens this measurement cycle and the normalized pulse from the output of the comparator 20 uniquely characterizes the magnitude of the Doppler frequency shift Δυ _{ADD i} . The specified delay - the time interval τ _back - is encoded in a buffer storage device (BZU) 23, common to all n channels, and the BZU at the same time has accordingly n channel inputs, as well as a control input associated with the second output of the GSI 22.

Figure 4 presents diagrams explaining the operation of the information processing channel using DLZ. On figa indicated a periodic sequence of clock pulses generated in the ICG 22 (figure 3) and determining the period of the measurement cycle. Fig. 4b shows the time-frequency characteristic of the heterodyning signals generated in the GLFM 21 (Fig. 3) supplied to the second inputs of the channel mixers 14. Fig. 4c shows the interaction of the LFM equivalent formed at the output of the mixer 14 (Fig. 3) with DLZ 16. fig.4g shown DLA generated at the output (3) "short" pulses of duration t _pulse and a time delay of τ with respect to their appearance _backside strobe.

Figure 5 shows a block diagram of the BZU 23 (figure 3), containing n multi-bit memory modules (ZM) 24, 25, 26, ... 27, to the information inputs of which are connected in parallel the output of the counter of temporary pulses (SVI) 28, recounted in which comes from the supply of high-frequency pulses to its counting input from a time-stamp generator (GVM) 29. The time code is recorded from the SVI 28 output to the corresponding memory modules 24, 25, 26, ... 27 when a pulse is recorded from the corresponding channel comparator 20 (FIG. 3). The block diagram of the CCD also contains a counter of measurement cycles (SC) 30, an input connected to the second output of the GSI 22 (figure 3), and two-input summing registers (DSR) 31, 32, 33, ... 34, overwriting the code information into which the first inputs are carried out at the beginning of the next measurement cycle from the action of the strobe pulse coming from the second output of the GSI 22 (Fig. 3), and the second inputs of the DSL are connected in parallel to the output of the SC 29, so that the code of the cycle number is written in the high register byte, and the code time delay τ _ass - in the lower bytes of the register. The GSI pulse 22 resets to the SVI 28 and after a certain delay time interval, organized by the delay element (EZ) 35, also resets the previously recorded codes in the corresponding ZM 24, 25, 26, ... 27 (to record new time codes in the next measurement cycle ) The pulse signals of the GPS 22 also carry out phase synchronization of the operation of the GPS 29, the pulse repetition rate in which is a multiple of the pulse frequency of the GPS 22 and determines the time sample of the time delay countdown τ _ass for each of the existing processing channels. The output of the BZU 23 (figure 3) is formed by signals from the GSI 22, DSR 31, 32, 33, ... 34 and SC 30. These signals are sent to the calculator of the measured parameters of the location object, the consideration of the specific structure of which is beyond the scope of the considered technical solution.

Figure 6 shows a geometric diagram for calculating the location of a location object using one (i-th) reflective glare on the sea surface, the position of which is defined by the measured angular coordinates - azimuth φ _i and elevation angle ε _i at a known height h _{0 of the} reference point of the locator relative to the surface of the sea (the reference point of the locator is located in the center of the receiving-transmitting lens). In this scheme, the OABD plane is vertical in x, z coordinates, the OCE plane is horizontal, coinciding with the sea surface, in x, y coordinates. In the vertical plane are the reference point A of the locator, the diffraction-limited (point) location object (point B), the height line of the reference point of the locator ОА = h ₀ , the location object BD = Н and the slant range AB = d. In the horizontal plane, the considered ith flare (point C) is located with the measured angles φ _i and ε _i on it. The line CG is the perpendicular to the line of intersection of the vertical and horizontal planes OD, which coincides with the x axis. By construction, OS = OE, therefore, the angles γ _i and σ _{i are found} from the relations tan γ _i = tan ε _i / cos φ _i and σ _i = ε _i -γ _i . The angle at the vertex B of the triangle ABG located in the vertical plane is denoted by χ _i and the angle at the vertex B of the spatially located triangle BCG is denoted by ψ _i . Since the triangles ABG and BCG are mutually orthogonal, it can be shown by simple calculations that the dihedral angle Θ _i between them is determined from the relation cos Θ _i = cos χ _i * cos ψ _i . In this case, the angle углом _i is the desired angle between the direction of the probing radiation of the locator and the direction of the scattered reflection from the located object, determined by the value of the Doppler shift Δυ _DOPi in the received radiation from this highlight of the sea surface. The value of an a priori unknown elevation angle ε ₀ to an invisible location object and the height of the last H above the sea surface are determined by the equation of communication with the slope range d of the form H = h ₀ + d sinε ₀ . The projection x _{i of} the oblique range line d _i in the i-th dimension in this diagram corresponds to the segment OD. The number of such independent measurements is m, so, as a result of averaging, we have

Considering the right triangle BCD (the angle at its vertex D is straight), we note that the BC line is the direction under which the location object is visible from a given highlight of the sea surface (from point C). In this case, the angle η _{i of the} observation of the location object from the flare under consideration is a function of the measured angles ε _i and φ _i and the Doppler shift Δυ _{DOP i} at a known value of h ₀ and varied parameters ε ₀ and v. Moreover, φ ₀ = 0, since it is believed that the oblique range line to the location object AB lies in the vertical plane zOx, that is, if the condition is met that the location object is illuminated by the probe radiation of the locator.

On figa and 7b presents a graphical interpretation of the location of the located object by the intersection of two (or more) circles located in different planes. The line of intersection of these planes AB is the line of oblique range. Point A is the reference point of the locator with known coordinates. Point B is the location point of the located object with a priori unknown coordinates. Points C ₁ and C ₂ are the points of glare on the sea surface xOy, the coordinates of which are easily calculated from the known height h _{0 of the} reference point of the locator and the measured azimuths φ ₁ and φ ₂ and elevation angles ε ₁ and ε ₂ . This allows you to calculate the coordinates of point B from the calculated angles Θ ₁ and Θ ₂ at the vertex B of the triangles ABC ₁ (figa) and ABC ₂ (fig.7b) by the method of intersection of circles.

Consider the operational nature of the proposed method.

As can be seen from figures 1 and 2, N _E elements of the matrix photodetector 1, the matrix of which can be, for example, rectangular (not necessarily square) with the number of rows p ₁ and the number of columns p ₂ with elements a _jk , where j = 1, 2 , 3, ... p ₁ are the row numbers of the matrix, k = 1, 2, 3, ... p ₂ are the column numbers of the matrix, can be formed in two different groups - two-dimensional (figure 1) or three-dimensional (figure 2), for where the conditions N _e p = ^pk, where p - dimension groups respectively equal to two or three. The value of the integer k is determined from the condition k = Ent [log _p (p ₁ * p ₂ )] + δ, where δ = 1 for log _p (p ₁ * p ₂ )> Ent [log _p (p ₁ * p ₂ ) ] and δ = 0 for log _p (p ₁ * p ₂ ) = Ent [log _p (p ₁ * p ₂ )]. So, for a matrix of 32 × 32 elements for a two-dimensional group, we have k = 5, and when forming a three-dimensional group, k = Ent [log ₃ 1024] + 1 = 3. However, in the latter case, there is a significant redundancy of the cubic structure of the matrix element mapping, since 3 ^{3 * 3} = 3 ⁹ = 19683 >> 1024, which means that with such a mapping of the matrix elements it is easier to ignore its 1024-729 = 295 elements so that k = 2, and then 3 ^{2 · 3} = 3 ⁶ = 729, or have the dimension of the matrix, for example, as 27 × 27. In another case, when the photodetector matrix has a dimension of 100 × 200 elements, for a two-dimensional group (p = 2) we have k = Ent [log ₂ (2 * 10 ⁴ )] + 1 = 15, and in this case 2 ¹⁵ = 32768 >> 20000, so it’s more profitable to take k = 14 and have a matrix with a dimension of 100 × 163 = 16300 elements. In this example, for a three-dimensional group (p = 3) it is advisable to choose k = 3, which allows us to display 19683 matrix elements with a cubic structure, the dimension of which should be reduced to 100 × 196 elements. These examples show that when determining the dimension of the photodetector matrix p ₁ * p ₂ , one should proceed from the following condition k = Ent [log _p (p ₁ * p ₂ )], respectively limiting the numbers p ₁ and p ₂ to obtain an integer value of k, for where the difference p ^pk -p ₁ * p ₂ > 0 and is minimal. Note that the choice of a square representation of a matrix in a two-dimensional group or a cubic in a three-dimensional group gives a minimum of the number of information processing channels, since a square determines its minimum half-perimeter for a given area, and a cube determines its minimum surface for a given volume in comparison with a rectangle and parallelepiped, respectively. So, a matrix with a dimension of 100 × 163 elements in a rectangular representation defines 100 + 163 = 263 processing channels, and in the corresponding two-dimensional group only 256 processing channels are required. If a rectangular matrix has a dimension of 50 × 326 elements (that is, the same area as the previous one), then the number of processing channels required for it will be 376 against the same 256 channels when converting such a matrix into a two-dimensional group. In the formation of a three-dimensional group for a matrix with a dimension of 100 × 196 elements, a cubic structure with a cube side of 27 elements determines the need for using 108 processing channels, and a parallelepipedal one of the same volume with side sizes of 27 × 9 × 81 will require the use of 126 processing channels, and for parallelepiped sizes 9 × 9 × 243 the number of channels increases already to 270.

If the number of elements in the photodetector matrix is selected from the condition N _Э = р ^kp , then the total number of processing channels should be equal to n = 2р ^k (р-1). Figure 1 presents a diagram of a two-dimensional group 1 with a dimension of 6x6 photodetector elements, each of which has two independent outputs. The outputs of these elements are connected to six horizontal and six column tires, which form two assemblies 2 and 3 with a total number of tires equal to twelve (n = 12). Figure 3 presents a block diagram of a three-dimensional group 4, forming a cube with sides of p elements. Moreover, the photodetector matrix 12 contains 3 ^3k elements α _jk each of which has two independent outputs. A cube 4 forming a three-dimensional group has only 2p ^2k tires along p ^2k mutually collinear tires for each of its two adjacent faces. The outputs of the elements of the matrix are connected to mutually orthogonal p ^2k buses of each of the p ^k layers of the cube. Each such layer is a two-dimensional group, the connection diagram of which is shown in figure 1. Therefore, to each of the cube buses, the corresponding elements of the matrix 12 are connected in parallel along p ^k . In this case, the p ^2k buses of each of the two faces of the cube form two square two-dimensional assemblies 5 and 6. Each of these two-dimensional assemblies contains p ^2k amplifiers 13 with two independent outputs . The inputs of these amplifiers are connected to p ^2k buses of the corresponding face of cube 4, the first outputs of amplifiers in each of the assemblies 5 and 6 are connected to p ^k buses of assemblies 7 and 9, and the second to p ^k buses of assemblies 8 and 10, so the total number of outputs tire is 2p ^k . So, for a photodetector 12 of 729 × 243 elements, we have p ^k = 27 and the total number of tires n = 4p ^k = 108. This allows reducing the amount of information processing equipment by more than two orders of magnitude from 19683 photodetector elements of the matrix 12. The gain in reducing the number of information processing channels when organizing a three-dimensional group is ψ ₃ = p ^2k / 4.

However, such a significant reduction in the number of information processing channels n leads to ambiguity in determining the group of two (at p = 2) or four (at p = 3) buses with the same Doppler frequency shifts Δυ _{ADD i} . Indeed, for a two-dimensional group (p = 2), the same information from one flare is contained in two buses. If glare is m, then the number of active information buses is 2 m. In order to select only two tires with the same information from this number, it is necessary to carry out (2m-1) searches, and the total number of choices of m pairs of tires, taking into account the successively retired tires (for already found pairs), is found by the following formula:

So, for m = 3 the maximum number of choices is q = 9, for m = 4 we have q = 16, and for m = 5 we get q = 25, therefore, q = m ² . It can be seen that with an increase in the number of active glare processed in the device m, the number of computational operations significantly increases, which should be taken into account when evaluating the speed of a computing environment.

In the case of a three-dimensional group (p = 3), the same information is contained on four tires out of the total number of active tires 4m (for m glare). The total number of options m for choosing m equinformation fours of tires is determined by the rule

So, for m = 3 the maximum number of choices is q = 21, for m = 4 we have q = 36, and for m = 5 we get q = 55. Thus, when moving from a two-dimensional group to a three-dimensional group, the amount of equipment needed for information processing decreases sharply, but the number of computational operations associated with enumerating options increases (approximately by half).

It will be shown below that the determination of the coordinates and speed of the located invisible object is possible when measuring azimuths φ _i and elevation angles ε _i by several highlights m of the sea surface and measuring Doppler frequency shifts Δυ ADP _i from these highlights (i = 1, 2, 3, ... m). The angles φ _i and ε _{i are} uniquely determined by the location of the photocell α _{jk of the} photodetector matrix, encoded by the numbers of the corresponding two (at p = 2) or four (at p = 3) buses with the same shifts Δυ _{ADD i} . The values of these frequency shifts are measured using a device whose block diagram for one of the n parallel processing channels is shown in FIG. 3.

The circuit consists of a series-connected mixer 14, a first broadband amplifier 15, a dispersion delay line (DLS) 16, a second broadband (compensating) amplifier 17, an amplitude detector 18, a minimum limiter 19, a comparator 20, and a storage unit (CCD) 23 with n information inputs. To the second input of the mixer 14 is connected the output of a linear-frequency-modulated oscillation (HLF) generator 21, to the triggering input of which a clock generator (GSI) 22 is connected, which sets the information processing cycle, for example, for a duration of 100 μs. The second output of the GSI 22 is connected to the control input of the BZU 23. Elements 21, 22 and 23 are common to all n channels of information processing on the elements 14-20.

The operation of the information processing channel is illustrated by graphs in figure 4.

On figa presents a sequence of clock pulses that determine the period of the write-read cycle and referred to as pulses of the "Reset Cycle" generated in the ICG 22. On figb shows the process of periodically reproduced LFM scanning in GLFM 21 with a frequency range from 80 to 130 MHz Fig. 4c, a straight bold horizontal line shows the signal from the output of the corresponding cell of the FPU 12 matrix in the “frequency-time” coordinates, for example, with a frequency of 53 MHz (from the estimated possible frequency range of 50-60 MHz), the bold sawtooth line shows the LFM equivalent formed at the output of the mixer 14, the frequency of which varies from 80-53 = 27 MHz to 130-53 = 77 MHz. Parallel to the sawtooth frequency change in the LFM equivalent, the dashed line shows the limits of variation of the latter when the input signal frequency changes in the range of 50-60 MHz (this range is denoted as ΔF _Σ ), and the pass band of the matched filter on DLZ 16 is indicated in the extreme horizontal dashed lines, in this example it is equal to 40 MHz, which allows you to get the duration of the "compressed" pulse at the output of the DLP t _imp = 1 / ΔF _lz = 25 ns, where ΔF _lz = 40 MHz is the frequency band of the DLZ. In the same graph, the dashed vertical lines show the boundaries of the variation in the time of occurrence of the pulse responses when the frequency of the input signal changes in the frequency range of Doppler shifts from 50 to 60 MHz. It can be seen that the Doppler frequency shift is converted into a time shift of the response pulse relative to the triggering clock indicated in figa. This circumstance is reflected in the second graph of FIG. 4d, which is a rectangular pulse with a duration of τ _ass equal to the difference in the times of the appearance of the response pulse and the preceding clock pulse. Note that this pulse width is then encoded in multi-channel BZU 23.

The operation of the information processing channel is associated with the assessment of the probabilistic characteristics of the detection of a location object, taking into account the characteristics of the receiving path.

As is known, the signal-to-noise ratio µ uniquely determines the probabilistic probabilistic characteristics of the locator [16, 17]. So, the probability of detecting P _obn signal against a background of normal (Gaussian) noise in accordance with the Neumann-Pearson criterion is determined by the signal-to-noise ratio μ at the input of the solver with the normalized threshold α _p = U _p / σ _w set in it, where σ _w - the rms noise voltage at the input of the decider, U _p is the threshold voltage, calculated from the expression

Where

is the probability integral, and the probability of false alarms P _lt is

For the values of the probabilities of detection and false alarms that are usually set when calculating location systems, the required signal-to-noise ratio is determined from the expression

where Ф ^-1 (x) is the inverse probability integral.

If the quality of the FPU is known (the value of the noise spectral density G _W ), then based on (5), it is possible to calculate the amount of required signal energy at the input of the FPU, which is sufficient for processing in a matched filter:

Instead of the probability of false alarms, the value of the frequency of false alarms F _l , which is determined by the expression

where <f _w> - the rms value of the noise band, which in the relative path narrowband assumption has expression <f _w> = (f ₀ + Δf ^{2 2/12) 1/2,} wherein f ₀ - signal carrier frequency (or center frequency tract ), Δf is the passband of the receive path with respect to which the noise band is calculated, and from the expression (7) the threshold voltage U _{p is} usually calculated, which is equal to:

The threshold voltage value obtained from (8) is substituted into expression (2) and the probability of detecting P _obn for the obtained signal-to-noise ratio at the output of the matched filter μ is found. Depending on the conditions set, they either decide to increase the viewing time at a given solid angle, or, conversely, to reduce this time or to increase the limiting detection range of the locator (or to increase the accuracy of the measured parameters of the object).

The operation of the multi-channel block storage devices (BZU) 23 is illustrated by the block diagram in figure 5. The circuit contains n parallel multi-bit memory modules (ZM) 24, 25, 26, ... 27, to the information inputs of which are connected in parallel the output of the counter of temporary pulses (SVI) 28, the conversion of which occurs from the supply to its counting input of high-frequency pulses from the time generator marks (GVM) 29. The time code is written from the output of the SVI 28 to the corresponding memory modules 24, 25, 26, ... 27 when the recording permission is applied to the inputs from the corresponding channel comparator 20 (Fig. 3). The block diagram of the CCD also contains a counter of measurement cycles (SC) 30, an input connected to the second output of the GSI 22 (figure 3), and two-input summing registers (DSR) 31, 32, 33, ... 34, overwriting the code information into which the first inputs are carried out at the beginning of the next measurement cycle from the action of the strobe pulse coming from the second output of the GSI 22 (Fig. 3), and the second inputs of the DSL are connected in parallel to the output of the SC 30 so that the code of the cycle number is written in the high register byte, and the code time delay τ _ass - in the lower bytes of the register. The GSI pulse 22 resets to the SVI 28, and after a certain delay time interval, organized by the delay element (EZ) 35, also resets the previously recorded codes in the corresponding ЗМ 24, 25, 26, ... 27 (to record new time codes in the next measurement cycle ) The pulse signals of the GPS 22 also carry out phase synchronization of the operation of the GPS 29, the pulse repetition rate in which is a multiple of the pulse frequency of the GPS 22 and determines the time sample of the time delay countdown τ _ass for each of the existing processing channels. The output of the BZU 23 (figure 3) is formed by signals from the GSI 22, DSR 31, 32, 33, ... 34 and SC 30. These signals are sent to the calculator of the measured parameters of the location object, the consideration of the specific structure of which is beyond the scope of the considered technical solution.

It is only important to note that the following operations are carried out in the calculator of the measured parameters of the location object:

- the choice of m pairs (at p = 2) or m fours (at p = 3) of buses with Doppler frequency shifts identical to them Δυ _{ADD i} for m glare measurements in this cycle by comparing codes with a given error, for example ± (1- 2) bits;

- determination by decryption of tire numbers in each pair (or four) of azimuths φ ₁ and elevation angles ε _i for all working m highlights;

- calculation of the coordinates and speed of the location object according to one of the possible algorithms, including iterative analysis of a priori unknown parameters - azimuth φ ₀ and elevation angle ε ₀ for the oblique range line to the location object and radial velocity v of the latter.

If the volume of computational operations turns out to be large, which does not allow it to be completed within a given or subsequent measurement cycle, then the calculations can be performed for several consecutive cycles, depending on the organization of the computing environment and its speed, and the results of the calculations should be related in time to the cycle under consideration. As the parameters of the located object (its coordinates and speed) are refined, the range of iterative search should automatically be reduced, thereby reducing the time spent on the necessary calculations up to a time interval equal to the measurement cycle time.

Using the claimed method of statistical averaging methods can improve the accuracy of measuring the coordinates and speed of motion of an invisible object.

Based on the use of methods of analytical geometry, the problem of meta-location of the located invisible object, when there is no direct reradiation from the latter along the oblique range line, is reduced to finding directions to the location object from several sea glare spaced in space, the intersection of which at known coordinates of these glare occurs at a point, which is the coordinates of the located object. Glare coordinates are uniquely determined by their azimuths φ _i and elevation angles ε _i , as well as by the height h _{0 of the} reference point of the transceiver lens of the locator above sea level, which is trivial. A more difficult task is to determine the angles η _i , at which the object is "observed" from the corresponding sea glare. To solve this problem, it is necessary to find the angles Θ _i (see Fig. 6), which are determined by the scattered reflection of laser radiation by the location object and are counted from the direction of the radiation probing the object (from the inclined range line). These angles for each of the active glare uniquely depend on the measured values of the Doppler frequency shifts Δυ _{DOP i} , since it is known that Δυ _{DOP i} = (2v / λ) cosΘ _i , therefore

that is, the angle Θ _i is determined by the measured value of the Doppler frequency shift and a priori unknown value of the radial velocity V of the located object, the value of which needs to be set.

The flight height H of an object above sea level is also an unknown parameter and is expressed in terms of a priori unknown values of the oblique range d and elevation angle ε ₀ according to the formula: Н = h ₀ + d sin ε ₀ .

It can be shown that the unknown parameters of the considered location problem are the radial velocity of the object v, the azimuth φ ₀ and the elevation angle ε ₀ , that is, the angular position of the oblique range line, and the measured parameters are the azimuths φ _i and elevation angles ε _{i of the} “vision” with m glare locator , Doppler frequency shifts Δυ _DOPi in radiation from these glare. However, taking into account the extremely narrow radiation pattern in the azimuthal plane, it can be considered that re-emission flares appear under the condition that the location object is irradiated with a locator, and, therefore, it can be assumed that φ ₀ = 0 or differs little from this value. The known constants in this case are the value of the height h _{0 of the} reference point of the locator above sea level and the wavelength λ of the laser radiation. Thus, an unambiguous solution to the location problem is possible by jointly solving a system of at least three independent equations during a sequential iterative enumeration of unknown parameters v and ε ₀ in such a way as to ensure a minimum error in determining the location of the object in space. In the process of solving a system of independent equations, the number of which can be chosen equal to m, but not less than three, the angles η _i are calculated, which determine the directions under which the location object is “observed” from the corresponding glare. Each of the angles η _i indicates only the slope of the observation line relative to the surface of the sea, that is, it forms a family of such identical angles, that is, a conical surface with a vertex of a cone at the location of the i-th glare on the sea and the height of the cone orthogonal to the sea surface. The combination of two such different cones when they intersect forms a second-order curve, on which there is a point corresponding to the coordinates of the object.

When three conical surfaces intersect from three different glares, three such curves are formed, respectively, which, intersecting each other, form a figure in the form of a curved triangle, inside which is the desired point corresponding to the coordinates of the object. The iterative enumeration of the values of the parameters v and ε ₀ reduces to minimizing the area of such a curved triangle, or to minimizing the distances between its vertices, which is essentially the same thing. An increase in the accuracy of positioning of a location object can be achieved by choosing a larger number of active glare (m> 3), although this leads to an increase in the volume of computational operations. Obtaining the minimum area of a curved triangle leads to the establishment of the desired exact values of the quantities v and ε ₀ , that is, to the actual solution of the location problem.

The range of iterations of the parameters v and ε ₀ is determined by the specifics of the location tasks, the tactical and technical characteristics of the objects being located (in particular, the a priori expected flight speeds) and the locator parameters (in particular, the size of its photodetector matrix). As for the range of iterations of the parameter φ ₀ , it is very small, which is determined by narrowly directed (fan-shaped) radiation in azimuth, and the variation of this parameter is used almost exclusively to ensure auto tracking of the object in azimuth, and in the calculations we can assume φ ₀ = 0, as this presented in Fig.6. The range of variation of the parameter v is determined by the a priori expected spread of radial velocities of the object, for example, the spread of Doppler frequency shifts with a band of 10 MHz, as in the example considered in Fig. 4, with an initial resolution of 100 kHz, which can change during the refinement of this parameter over several successive cycles measurements. The range of variation of the parameter ε ₀ is determined by preliminary intelligence information for the target object (in particular, its altitude above the sea surface) and the dimension of the photodetector matrix along its columns.

Note that, as data on the parameters v and ε _{0 are} obtained, the ranges of variation of these parameters can be significantly reduced, which will allow solving the location problem in less time, for example, within one cycle following the cycle under consideration. This possibility is due to the fact that the time change of these parameters is relatively insignificant during one cycle, is beyond the instrumental error of measuring the values of v and ε ₀ .

The solution of the location problem in the claimed technical solution can be significantly simplified provided that the optical axis of the transceiver lens of the locator and the oblique range line AB on the location object (see Fig.6) lie in the same plane, in the vertical plane zOx, so that φ ₀ = 0. This condition is almost always fulfilled, otherwise there would be no glare from the object, and the task of automatically tracking a moving object in azimuth just comes down to ensuring the equality φ ₀ = 0. Moreover, as can be seen from Fig.6, the reference point A of the locator and point B, determined by the coordinates of the object, lie in a vertical plane. At point C, the ith highlight is located on the sea surface, visible by a locator with an azimuth φ _i and elevation angle ε _i from a height OA = h ₀ . This flare is located at a distance OG = h ₀ cos φ _i / tg ε _i along the x axis and at a distance CG = h ₀ sin φ _i / tg ε _i along the y axis. Triangle ABC is formed by the oblique range line to the object AB = d and two direction lines from the locator to the glare AC = (h ₀ ² + CG ² + OG ² ) ^1/2 = h ₀ / sin ε _i and from the reflection to the aircraft object, the length of which is not yet known. However, it is known that the angle at vertex B of this triangle ABC is Θ _i and is determined from (9). Since the triangle BCG is perpendicular to the vertical plane zOx, since CG⊥OD and CG lie in the plane of the triangle, from the well-known relation cos Θ _i = cos χ _i * cos ψ _i we can find from (9) the value of the angle ψ _i according to the relation cos ψ _i = cos Θ _i / cos χ _i = λ Δυ _DOPi / 2v cos χ _i , and the value of the angle χ _i is found from the consideration of triangle ABG. Note that, by construction, OE = OS = h ₀ / tan ε _i and the segment EG = OE-OG = tan ε _i / cos φ _i (1-cos φ _i ) / tan ε _i . We note that tan γ _i = h ₀ tan ε _i / h ₀ cos φ _i = tan ε _i / cos φ _i and γ _i = ε _I −σ _i = arctan (tan ε _i / cos φ _i ). From the triangle BDG we express the angle at its vertex G through the yet unknown height Н = BD = h ₀ + d sin ε ₀ as follows: tg (∟BGD) = Н / (OD-OG) = (h ₀ + d sin ε ₀ ) / (d cos ε ₀ -h ₀ cos φi / tan ε _i ), whence for the angles γ _i and ∟BGD we obtain the equalities:

γ _i = arctan (tan ε _i / cos φ _i ),

Moreover, the angle ∟AGB at the vertex G in triangle ABG is

The angle at vertex A of triangle ABG is obviously equal to

whence we find the value of the desired angle at the vertex B in triangle ABG:

Taking into account the relation cos ψ _i = λΔυ _DOPi / 2v cosχ _i indicated above, from (13) we find the value of the angle ψ _i and the length of the side of the BC in triangle BCG, which is equal to

From the consideration of the right-angled triangle BCD, we find the value of the angle η _i at the vertex C by the definition sin η _i = Н / ВС = (h ₀ + d sin ε ₀ ) tan ε _i [1- (λ Δυ _DOPi / 2v cos χ _i ) ² ) ^1/2 / h ₀ sin φ _i = [1+ (d / h ₀ ) sin ε ₀ ] tg ε _i [1- (λ Δυ _ADPi / 2v cos χ _i ) ² )] ^1/2 / sin φ _i .

When substituting the values of the angles χ _i in this expression for sin η _i from expression (13), we find the angles η _i relative to the verticals reconstructed from the dislocation points of the sea glare that form the group m of the previously mentioned conical surfaces, the intersection of which reconstructs a point in the space in which there is a diffraction limited (point) location object. This equation includes three unknown quantities - ε ₀ , V, and d, of which the first two are found by sequential iteration in the given ranges, and the third is searched for when solving a system of independent equations with at least three (m≥3). As a result, we obtain m values of the inclined range d _i for which the absolute value of the difference of any pair of these values should have the minimum possible value. The average value of the slant range is

and the variance

minimal when correctly selected variable unknowns ε ₀ and v.

Another solution to the location problem is also possible, not related to calculating the angles η _i and using the technique of intersecting conical surfaces. This solution, based on the so-called intersecting circle method, is geometrically presented in FIGS. 7a and 7b. It is believed that in the mode of automatic tracking of the located object in azimuth, taking into account the narrowly directed probe radiation in the azimuth plane, when sea glare from scattering by the laser irradiation object occurs, the reference point A of the locator and the object location point B, that is, the oblique range line AB, lie in the vertical plane xOz. As you know, through these points A and B one can draw countless circles, and through three points only one unique one. Moreover, the different spatial position of these third points (C ₁ and C ₂ ) leads to noncollinearity of the planes in which these circles lie, and the line of intersection of these planes corresponds to the line of inclined range to the object. The coordinates of points A and C ₁ (A and C ₂ ) are known, and the coordinates of point B are not known a priori and must be calculated. It is easy to understand that point B corresponds to the intersection point of circles drawn through three points - the first through A, B and C ₁ , and the second through A, B and C ₂ . However, to determine the coordinates of the centers of these circles O ₁ and O ₂ lying in the planes of the corresponding triangles ABC ₁ and ABC ₂ , as well as the values of their radii r ₁ and r ₂ , it is necessary and sufficient to determine the angles Θ ₁ and Θ ₂ at the vertices B of the indicated triangles based on the chords AC ₁ and AC ₂ . The measurement of these angles corresponding to the angles between the scattering directions of the laser radiation object to the corresponding glare of the sea surface and the sounding direction coinciding with the inclined range AB line is based on measuring the Doppler frequency shift Δυ ADP _i in the radiation received by the locator from two glare.

Consider the task of determining the coordinates of the center of the circle O ₁ (figa) and its radius r ₁ . The x, y, z coordinates of points A, B and C _{1 are} as follows: A (0, 0, h ₀ ); B (x, 0, h ₀ + x tan ε ₀ ); C ₁ (h ₀ cos φ ₁ / tg ε ₁ , h ₀ sin φ ₁ / tg ε ₁ , 0). Moreover, x and ε ₀ are a priori unknown quantities. The chord length AC ₁ is equal to AC ₁ = h ₀ / sin ε ₁ . The center of the circle O ₁ lies on a perpendicular drawn from the center of the segment AC ₁ . For a known angle Θ ₁ at the apex of triangle ABC ₁ and provided that point B lies on this circle, the perpendicular length h ₁ ^* from the middle of the chord AC ₁ is from point F ₁ with coordinates F ₁ (h ₀ cos φ _1/2 tg ε _1, h ₀ sin φ _1/2 tg ε _1, h _0/2) - equal to h ₁ ^* = r ₁ cos Θ _1, wherein the radius of the circle is r ₁ = h _0/2 sin ε ₁ sin Θ _1.

For the corresponding circle in figb we get h ₂ ^* = r ₂ cos _{2 2} and the radius r ₂ = h ₀ / 2sin ε ₂ sin Θ ₂ . The intersection of these two circles occurs at point B, the coordinates of which x and z are calculated as functions x = f (h ₀ , ε ₀ , ε ₁ , φ ₁ , v) and z = g (h ₀ , ε ₀ , ε ₁ , φ ₁ , v) with a variation of the parameters ε ₀ and v, with the correct choice of which and with the number of effective glare m> 2, the distance between the intersection points of m circles near point B is minimal. In the latter case, a system of m independent equations is solved with successively varying parameters ε ₀ and v, as a result of which the values of x _{i are found} with a minimum spread of their lengths.

This technique is interesting in that it allows a very significant reduction in the ranges of variation of the parameters ε ₀ and v if the number of effective glare m> 2. Indeed, the coordinates of the object - point B: x = f (h ₀ , ε ₀ , ε ₁ , φ _i , v), y = 0 and z = g (h ₀ , ε ₀ , ε _i , φ _i , v) can be determined by solving a system of three independent equations (for m = 3) without applying the operation of iterative search for parameters ε ₀ and v. Thus, data on these parameters is obtained, which allows one to reduce the range of iterations in subsequent measurements, while simultaneously reducing the discrete iterations in order to increase the accuracy of measuring the coordinates of the object.

Automatic tracking of the transceiver lens of the locator in azimuth ensures the alignment of the optical axis of the lens with the direction of sight of the location object, that is, with the line of inclined range AB (Fig.6 and 7). This ensures the equality φ ₀ = 0 (the angle φ ₀ indicates only the mismatch in the azimuthal plane of the optical axis of the lens relative to the axis of sight of the object, but not the value of the azimuth to the object, measured relative to the north direction). Variation within small limits of the angle φ _{0 is} used in the locator to automatically track an object in azimuth according to the criterion of the maximum power of received optical signals from glare of the sea surface. Therefore, the algorithm for solving the location problem does not include iteration along the azimuth φ ₀ .

Consider an example of building a location system.

When forming a photodetector matrix with a dimension of 181 × 181 CMT elements with an element diameter of 0.1 mm, the minimum matrix size is 18.1 × 18.1 mm ² , and the viewing angles in the azimuthal Δφ and elevation Δε planes are Δφ = Δε = 0.05 rad when the focal length of the receiving lens F _CR = 360 mm With a height of the reference point h ₀ = 30 m and a minimum observation range of the sea surface L _min = 500 m (i.e., with ε _max = arctan (h ₀ / L _min ) = 0.06 rad), we obtain ε _min = ε _max -Δε = 0.01 rad, and the maximum range of vision of the sea surface is L _max = h ₀ / ε _min = 3000 m, that is, the length of the location of the sea glare visible by the locator is 2500 m.The width of this area grows linearly along its length from s _min = L _min * Δφ = 500 * 0.05 = 25 m to s _max = L _max * Δφ = 3000 * 0.05 = 150 m - at the end of the vision zone on the sea surface. If the receiving lens of the locator is executed as a zoom lens, then it is possible to widely vary the length of the working area in which sea glare is observed, as well as its position along the length when changing the position of the optical axis of the receiving lens. So, with a focal length F _CR = 120 mm, we obtain Δφ = Δε = 0.15 rad and the length of the zone of glare visible by the locator can be set in the range L = 0.2 ... 9 km with a zone width of s = 30 m ... 1.35 km. It is also important to note that the fan-shaped radiation pattern of the transmitting lens of the locator may be smaller than the viewing width in elevation in the receiving lens, since the radiation does not need to be directed towards the sea surface, however, the optical axes of the receiving and transmitting lenses of the locator should always be in the same plane. Finally, the configuration of the arrangement of photosensitive elements in the matrix may differ from a rectangular one. For example, it can be trapezoidal, which will expand the observation zone of the sea surface in the near zone, narrowing it in the far, that is, make this zone equally wide in width along the entire length of the review.

If we assume that the angles Θ _i are in the range Θ _i ≤π / 3, then when working on invisible objects moving at a speed of 300 m / s at altitudes of 30-50 m above sea level, the range of variation of Doppler frequency shifts for gas radiation The CO ₂ laser (λ = 10.6 μm) will be equal to 8.4 MHz, that is, does not exceed the value ΔF _Σ = 10 MHz indicated in FIG.

In total, 181 ² = 32,400 elements are used in the matrix, which allows you to build a three-dimensional group with a cube side of 32 elements, which corresponds to 128 channels of information processing at the DL. The latter can have a frequency band ΔF = 40 MHz and the duration of the impulse response τ _dz = 50 μs (the base of the DLZ is equal to B = 2000), which allows to increase the signal-to-noise ratio at the input of the resolver by ^{1/2 1/2} = 45 times, which compensates for the deterioration this ratio 32 ^1/2 = 5.7 times due to an increase in noise power by connecting to the output buses of assemblies 7-10 (Fig. 2) thirty-two outputs of amplifiers 13. “Compressed” pulses at the outputs of the DLZ have a duration of t _imp = 25 ns , it is advisable to choose a measurement cycle duration of 100 μs. When the speed of the located invisible object is v = 300 m / s during the cycle, the object passes a path of only 3 cm, which allows us to assume that glare is stable throughout the entire cycle. The clock frequency in the computer 29 is chosen not lower than 80 MHz, while the time position codes of the DLZ response pulse should be 13-bit (the least significant bits in the DSL 31, 32, 33, ... 34). The time delay in element 35 (of the order of 1 μs) ensures the reset of the codes in ZM 24, 25, 26, ... 27 after the data recorded in them are transferred to the lower bits of the DSR 31, 32, 33, ... 34 at the beginning of a new cycle.

For the practical use of the proposed method in the laser location of low-flying invisible aerial objects, it is necessary to study the glare statistics of reflections at sea (in the ocean) in various weather conditions, the energy of these optical signals, the primary zones on the sea surface for receiving glare reflections when specifying a certain class of invisible objects . In addition, it is necessary to develop an appropriate high-speed computing environment for multichannel processing of encoded signals and develop a photodetector array, for example, with SRT elements, with a low noise level and a high density of photodetector elements in it. As a laser, powerful gas single-frequency devices with high short-term frequency stability of radiation should be used. It is also recommended that the development of multi-channel dispersion delay lines in an integrated design with a large base allow to compensate for the effect of noise when several two-dimensional or three-dimensional groups of several photodetector elements of a matrix are connected on one bus in parallel. Of interest is the development of a transceiver lens of the locator with zoom of the receiving lens and a fan-shaped radiation-reception diagram with the corresponding precise actuators for controlling the angular position of the lenses.

Appropriate R&D for the location system under consideration can be carried out at enterprises of the Ministry of Industry related to the development of optoelectronic devices in the interests of tactical tasks of the Russian Navy.

Literature

1. O.F. Smaller, Laser Doppler Locator. RF patent No. 1829641.

2. O.F. Smaller, Detector of a laser Doppler radar. RF patent No. 1829640.

3. O.F. Smaller, Consistent Filter, RF Patent No.2016493.

4. O.F. Smaller, Device for analyzing the spectrum of signals. RF patent No. 2040798.

5. O.F. Smaller, Method of location. RF patent No. 2296390.

6. Laser location. Ed. N.D.Ustinova. - M.: Mechanical Engineering, 1984.

7. V.V. Protopopov, ND Ustinov, Infrared laser location systems, M .: Military Publishing House, 1987.

8. Measurement of spectral-frequency and correlation parameters and characteristics of laser radiation. Ed. A.F. Kotova and B.M. Stepanov. - M.: Radio and Communications, 1982.

9. C. Cook, M. Bernfeld, Radar signals, trans. from English, ed. V.S.Kilzon. - M .: Owls. Radio, 1971.

10. Filters on surface acoustic waves. Ed. G. Matthews. - M .: Owls. Radio 1981, 472 pp.

11. V.I. Tverskoy, Dispersion-time methods for measuring the spectra of radio signals. - M .: Owls. Radio, 1974, 240 p.

12. A.A.Dzhek, P.M. Grant, J.H. Collins, Design Theory and Application of Fourier Processors on Surface Acoustic Waves, TIIEIR, 1980, No. 4, p. 22-43.

13. Filters on surface acoustic waves, technology and application, trans. from English G. B. Zvorono. Ed. V.B.Akpambetova. - M.: Radio and Communications, 1981.

14. Ya. D. Shirman, VN Manzhos, Theory and technique of processing radar information against a background of interference. - M.: Radio and Communications, 1981.

15. Yu.S. Lezin, Optimal filters and pulse signal storage devices. - M .: Owls. radio, 1969.

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17. V.I. Tikhonov, Optimal signal reception. - M .: Radio and communications, 1983, 320 p.

Claims (7)

1. A method of processing information in a laser coherent locator with a matrix photodetector, based on measuring Doppler frequency shifts Δυ ADI _i in emissions from sea glare and the angular coordinates of the latter - azimuths φ _i and elevation angles ε _i , calculating the coordinates of the location object and its speed, followed by statistical averaging of the calculated parameters over several adjacent measurement cycles, characterized in that in N _e = p ^{kp the} elements of the photodetector array form two independent outputs that form into two-dimensional (p = 2) or three-dimensional (p = 3) groups, where k = 1, 2, 3, ... are integers, with n = 2p ^k (p-1) output buses in the groups, parallel to each output bus of the group is r = p ^k the corresponding outputs of the row or column elements of the matrix photodetector, and the calculation of the coordinates of the location object according to the measured Doppler frequency shifts Δυ _{DOP i} with the corresponding measured angular coordinates - azimuth φ _i , and elevation angle ε _i to the corresponding α _i glare of the sea surface, visible by the locator in this measurement cycle, where i = 1, 2, 3, ... m is the number of valid x flare radiation, is carried out by sequential iteration of unknown parameters - the radial velocity V of the location object in the a priori expected interval of its permissible change and elevation angle εо of the oblique range line to the location object, for which, during the indicated iterative selection of these parameters, their values of v and εо are chosen at which the differences between any pairs of quantities that determine the slant range to the location object are minimized. 2. The method according to claim 1, characterized in that the resulting uncertainty of the choice of 2 (p-1) output buses corresponding to the same Doppler frequency shift Δυ _{ADD i} in the signal at the outputs of the element α _{jk of the} photodetector, according to the position of which in the matrix judge the azimuth φ _i , and the elevation angle ε _i , to the visible sea glare α _i , is eliminated by comparing the codes displaying Doppler frequency shifts, by their 2 (p-1) -fold coincidence for all m sea glare with a given minimum error. 3. The method according to claim 1, characterized in that the calculation of the measured parameters of the location object with a large amount of computational operations associated with the iteration process when searching for v and εo values satisfying the specified condition is performed in a time interval exceeding the specified measurement cycle, and then relate the results to the point in time of the initial measurement cycle. 4. The method according to claim 1, characterized in that the reduction in the volume of computational operations during the iterative search of the values of v and εo in each subsequent measurement cycle is achieved by reducing the interval of their iterative search, taking into account data on these values from previous measurement cycles and taking into account statistical averaging each of these values over several consecutive measurement cycles under the assumption that the found values of v and εo are slowly varying functions of time in comparison with a given rate of repetition of cycles and dimensional. 5. The method according to claim 1, characterized in that the coordinates of the located object are refined by performing an iterative search of the values of v and εо by a joint solution of the system m of equations x _i = f (ho, εо, φ _i , ε _i , v) for all visible locator m of glare of the sea, that is, for i = 1, 2, 3, ... m, where the scattering angle of the object of the probing radiation relative to the direction of the latter is
Θ _i = arccos (Δυ _{DOP i} · λ / 2v), λ is the wavelength of laser radiation, h _v is the known height above sea level of the center point of the receiving lens of the locator, so the x coordinate is calculated by the formula

and at the same time, the absolute value of the difference between any two values of x _i with different indices i from their number m is minimized. 6. The method according to claim 1, characterized in that the detection of the location object and its auto-tracking is carried out by scanning the probe radiation in azimuth, and the radiation pattern is chosen fan-shaped - extremely narrow in azimuth and wide in elevation. 7. The method according to claim 1, characterized in that when the conditions for detecting the location object and its auto tracking in azimuth are fulfilled, in which the oblique range line and the optical axis of the locator transmitting lens lie in one plane, the location of the location object and the measurement of its radial speed find the calculation of at least two different glare radiation (Min m = 2) in a given measurement cycle.

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