RU2392635C2 - Method for detecting and determining coordinates of search object - Google Patents

Abstract

FIELD: physics, navigation.

SUBSTANCE: invention relates to methods for radar detection on the locality of small objects. The location method, which is based on using side-looking synthetic aperture radar (SAR) mounted on a carrier in form of aircraft, involves generation of preliminary data on the search object and its coordinates, determination of the flight path of the carrier and the location zones for the SAR based on these data, flying the aircraft to the given path and location of these zones using SAR with simultaneous determination using the navigation system (NS) of the aircraft and recording the spatial position of phase antenna centres (PAC) of the SAR during each probing, obtaining long-wave holograms at the output of the SAR and recording the said holograms, formation of a radar image of given location zones based on the long-wave holograms and spatial positions of the PAC, detection of an object on that radar image, its identification and determination of its geodesic coordinates; K≥2 SAR channels operating in different frequency ranges are used. Resolution in the channel with the greatest carrier frequency and with the best resolution is matched with dimensions of the detected object. During location, primary detection of the object in the location zone is carried out first, selecting a SAR channel with the best contrast of the signal of the search object on the background of the locality, and results of primary detection are used in the channel with the greatest carrier frequency, for which fragments of the detailed radar image are formed, the number, position and dimensions of which correspond to primary detection data. The search object is detected and identified on these fragment and its position in the screen coordinate system is determined, the position in a geodesic coordinate system of which is determined from estimations of geodesic coordinates of the SAR PAC of that channel, and further, geodesic coordinates of the object are recalculated. To increase efficiency of the method, additional location of selected sections of the locality using a high resolution channel is carried out based on results for primary detection of the object. For the same purpose, a search zone is further formed on radar images formed in primary detection channels and primary detection of the object is carried out in that zone. If there is a passive locator (PL) on the carrier during detection and determination of the coordinates of the object, whose position is related to a radiofrequency radiation source, generation of preliminary data on the search object and selection of SAR parametres is carried out from data of this PL, where if possible, the path of the carrier is used to make a synthesised passive antenna system, optimising it and operating time of the PL and SAR. To achieve the required accuracy of determining coordinates of the object, requirements are specified for NS data when evaluating PAC during single probing of the location zone and during repeated probing while changing the aspect by an angle close to 90 degrees. Proposed also are methods for smoothing NS data based on features and requirements for side-looking SAR in the solved tasks, as well as use of self-focusing in a long-wave channel in order to correct NS errors.

EFFECT: method increases efficiency of on-line detection of a small object and accuracy of determining its geodesic coordinates.

11 cl, 6 dwg

Description

The invention relates to methods for radar sensing of the terrain for the rapid detection against the background of the earth (water) surface of small objects, their recognition and determination with high accuracy of their location, for example, when mapping, compiling a detailed digital map of the terrain, compiling a land cadastre, determining the natural or industrial disaster, its scale and consequences. The same tasks have to be solved with the help of the injured and those in distress, for example, when searching for them or when cargo is delivered using aircraft (LA) to a point with specified geodetic coordinates.

In this case, two related tasks are successively solved: first, it is necessary to detect the required objects or the required fragments of the terrain, distinguish them and distinguish them from other objects, recognize them, and then determine their coordinates, for example, geodesics. The relationship between these tasks lies not only in their intersection in time, as, for example, in multi-stage detection, but also in the fact that their effectiveness is largely determined by the same factors, and the conditions for effectively solving the two problems under consideration are sometimes contradictory. For example, the high resolution and detail of an object required when solving problems of recognition and determination of the coordinates of an object can significantly complicate the task of its detection. In particular, in a synthetic aperture radar (PCA), an increase in resolution is associated with the use of a high carrier frequency of the probe signal. But an increase in this frequency leads, as a rule, not only to an increase in the resolution of the SAR, but also to an increase in reflections from the area, which complicates the selection of the desired objects against the background of this area.

Currently, there are various methods and means of aviation remote sensing. These are digital and analog aerial cameras, radars, spectrozonal and thermal imaging scanners, etc. All of them provide the formation of one or another image of the earth (water) surface and objects on it of appropriate quality, by which they solve the problems of detection, recognition, identification of natural and industrial objects , various structures, etc. Thus, the first of the above problems is solved.

The second task - the determination of geodetic coordinates - is now more and more successfully solved by the direct geo-location method (see, for example, an article by EM Medvedev. “GPS / IMU Integrated Navigation Systems”, Geoprofi Journal, 3-6, 2005). At the same time, navigation sensors are used on board the aircraft, which record the position of the sensing devices directly in the process of this sounding. Based on these navigation data, they determine the geodetic coordinates of objects found on images of the earth's surface. This method significantly wins over the usual standard photogrammetric procedure, which, as you know, includes operations such as selecting landmarks and determining their geodetic coordinates, determining tie points on stereo pairs, developing and adjusting the phototriangulation network, etc. These traditional approaches cannot be used for operational work, since the main processing to determine the geodetic coordinates is carried out in this case on the ground after flights.

Currently used integrated navigation systems based on the combination of GPS satellite navigation and inertial navigation sensors (GPS / IMU integrated systems) are almost completely free from the disadvantages associated with the complexity of the traditional approach. We can assume that all the numerical parameters necessary for the final location of the survey data arise simultaneously with these data directly during the survey (see, for example, the same article by E.M. Medvedev).

Thus, direct geolocation in principle allows us to solve the problem of the operative determination of geodetic coordinates. However, with regard to the accuracy of determining the position of objects, simple geo-positioning according to the article “Intelligent Systems ...” (http://www.hprobotics.com/statji_1.asp?id=15 dated 03/31/2007) currently has an accuracy of 30 and 90 meters. This is possible and sufficient for general orientation, but completely insufficient for detecting small objects and accurately determining their coordinates. However, the accuracy of modern direct geolocation systems themselves is very high. Thus, the POS AV 510 integrated navigation system, when its satellite system operates in differential mode (see http://www.geolidar.ru/facilities/equipment/posav/posav/tech.php), allows you to determine the geodetic coordinates of its location with accuracy up to 0.5-2 m. However, these accuracy does not yet guarantee high accuracy in determining the geodetic coordinates of objects detected in images obtained using remote sensing. In particular, this applies to SARs, in which radar images (RLI) are the result of processing signals obtained over a sufficiently long synthesis interval over which the SAR performs multiple sounding, and for each sounding, the position of the antenna phase center (PCA) must be estimated ) PCA.

For example, we can consider the calculation of geodetic coordinates in SAR. The very principle of constructing radar data (see, for example, the article by Bryzgalov A.P., Karaulova E.V., Khnykina A.V. “Analog-digital data processing in synthesized aperture radars using ultra-wideband signals with linear frequency modulation” in the journal “Digital signal processing” No. 4 of 2004), in which the image is calculated based on the estimates of the position of the PCA PCA for each sounding in the synthesis interval, provides a fairly rigid binding of the radar image to these positions. Moreover, errors in the knowledge of the position of the PCA should not exceed the linear resolution of the SAR (for example, 1-2 m), which, in general, is consistent with the accuracy of the previously mentioned modern navigation systems, such as the POS AV 510 system. Otherwise, the radar will not be formed. But it is still necessary to ensure coherent accumulation of signals during the synthesis interval. This is usually achieved by the use of self-focusing algorithms (see, for example, the book by G. Kondratenkov and A.Yu. Frolov, “Radio vision.” M.: “Radio engineering”, 2005). However, it can be shown that if there is even a small correlated component in the error in estimating the position of the PCA PCA in the synthesis interval (approximately in time this amounts to 1 or more seconds of flight of the carrier), this can lead to such errors in determining the geodetic coordinates of the object detected on the radar image, which significantly (by orders of magnitude) exceed the errors of the National Assembly. And the presence of a correlated component in navigation errors, in the general case, can be due to both the nature of the navigation data and its processing, and the very method of constructing radar data.

Of the sensors and imaging devices — aeronautical remote sensing equipment — most sensors and imaging devices, except for SAR, have a small range of vision and are highly dependent on working conditions: time of day, weather conditions, etc. Most of these sensors cannot work in difficult weather conditions. Direct sensing radars (without aperture synthesis) have a low azimuth resolution.

Therefore, of the known analogues, the remote sensing method, as set forth, for example, in the previously mentioned book by G. Kondratenkov, was selected as a prototype. and Frolova A.Yu. "Radiovision". M .: "Radio Engineering", 2005, based on the use of SAR and NS installed on one aircraft, for example, on an airplane. It is possible to use an integrated navigation system such as GPS / IMU as a NS (see the article by E.M. Medvedev cited earlier). In accordance with the indicated book by G. S. Kodratenkov and A. Yu. Frolov, first, in accordance with the task, the desired object is determined and preliminary data on its coordinates are formed: the estimated coordinates and error estimates when determining these coordinates. Based on these data, determine the path of the carrier and the location zone for the SAR, where the desired object can be located. Then, the carrier is brought to a predetermined flight path and, using X-ray diffraction, probing the previously defined location zone is carried out with simultaneous determination with the help of NS and storing the spatial position of the PCA of the SAR at each sounding, for example, its geodetic coordinates. According to the location results, using the coordinates of the PCA, the formation of radar images of the specified location zone is carried out. Typically, these radar displays on the screen of the PCA operator. But in any case, the radar image is built in some screen coordinate system associated with the coordinates of the PCA PCA in the sounding interval necessary for the formation of this radar image. An XRD operator based on a radar image, displayed, for example, on a PCA screen, or a computer system in accordance with a special algorithm implemented in it, detects an object on this radar, performs its recognition and determines the position of the object on the radar, that is, in the screen coordinate system. Next, the screen coordinate system is linked to geodetic coordinates, for example, using the NS or by estimating the coordinates of an object with known coordinates, or in another way, and then the geodetic coordinates of the desired object are determined.

Modern SARs make it possible to obtain radar images with high (for example, up to 10 cm) resolution, which in principle makes it possible to see and distinguish (i.e., detect and recognize) even small objects. However, increasing the resolution seriously complicates the task of real-time object detection.

Firstly, in this case, as a rule, the rate of computing the radar information line increases and the amount of calculations increases. The pace of the formation of the line of radar data, for example, in real-time operation is determined by the time the carrier travels a portion of the path corresponding to the linear resolution of the SAR along the path of the carrier. And the increase in the volume of calculations is also associated with the need to increase the synthesized aperture. Indeed, if, for simplicity of presentation, we neglect the curvature of the earth and assume that the PCA carrier performs linear motion at a constant speed (and at a constant height) along the Y axis, and the X axis is perpendicular to it (and horizontal), then in this case the linear resolution of the side-view locator along the Y axis ("in azimuth") is determined by the expression:

where X _rev is the distance to the located site (object) of the area relative to the flight path of the carrier, D _synt is the length of the synthesized aperture, λ is the wavelength of the probing SAR signal. From the expression (1) it follows that in order to increase the resolution, the synthesized aperture should be increased. And this leads to an increase in the number of soundings that should be used in the formation of one line of radar data, that is, the amount of computation during its formation significantly increases. These reasons practically do not allow at the moment to implement the operational formation of radar data and reliable operational detection of a small object.

On the other hand, in accordance with (1), an increase in the linear resolution of the SAR along the flight path of its carrier, as already noted, is usually associated with a decrease in the wavelength λ of the probe signal, i.e., with an increase in its carrier frequency. So, in modern PCA LYNX APY-8 (see, for example, Lynx: A high-resolution synthetic aperture radar. SITsunoda F. Pace, J. Stence, M. Woodring. General Atomics. PO Box 85608, San Diego, CA 92121-5608. WHHensley, AWDoerry, BCWalker. Sandia National Laboratories. PO BOX5800, MS 0529, Albuquerque, NM, 87185-0529), which provides a resolution of up to 10 cm, uses a frequency of about 16.7 GHz. But at these frequencies the reflections from the terrain (forests, fields, etc.) are significant, many details appear, and the task of detecting the desired object is comparable to the task of detecting a “needle in a haystack”. This contradiction is partially resolved by preliminary data issued by SAR. However, in practice, the accuracy of the preliminary data, the existing computing facilities and the capabilities of the operator as the main link in the detection and recognition circuit of an object do not allow, as a rule, to reliably provide a solution to the problem of operational detection and identification of objects, especially small ones.

In addition, as noted earlier, the resulting accuracy in determining the geodetic coordinates of detected objects remains low even when using navigation sensors in conjunction with SARs with high accuracy in determining their own coordinates.

The objective of the invention is to significantly increase the speed of detection and recognition of small objects and the accuracy of determining their geodetic coordinates using SAR installed on a mobile carrier, and the direct positioning of the SAR antenna using NS mounted on the same carrier.

The essence of the invention lies in the fact that in the method for detecting and determining the coordinates of the desired object, including the use of an SAR installed on an aircraft, the formation of preliminary data about the desired object and its coordinates, determining, based on these data and the characteristics of the selected aircraft and SAR, the carrier path and zone locations for the SAR, the exit of the aircraft on a given trajectory and the location of this zone using the SAR with simultaneous determination using the NS of the aircraft and storing the spatial position of the PCA PCA for each probe and, for example, their geodetic coordinates, obtaining at the output of the SAR receiver a radio hologram (RG) and their storage, forming a radar image (RLI) of the specified location zones due to the processing of the RG during the synthesis interval taking into account the spatial positions of the PCA and using self-focusing methods, detection on this The radar image of an object, its recognition and determination of its position in the screen coordinate system with the subsequent determination of the geodetic coordinates of the object, use K≥2 SAR channels operating in different often ranges, and the resolution in the channel with the highest carrier frequency is consistent with the size of the detected object, NS choose from the condition that the NS errors in determining the position of the PCA PCA do not exceed the resolution of the PCA, and when locating, the object is first detected in the location zone, choosing SAR channels with high contrast of the signal reflected from the target object against the background of the terrain, and the results of primary detection are used in the SAR channel with a high carrier frequency, in which a fragment is formed you are detailed radar images, the number, position and sizes of which correspond to the data of primary detection, and on these fragments the desired object is detected, recognized and identified and its location in the screen coordinate system is determined and then the object coordinates are converted to geodetic coordinates, while the screen coordinate system is linked to the geodetic coordinate system is carried out based on estimates of the geodetic coordinates of the PCA PCA of this channel.

In order to increase the efficiency of the method and create conditions for partial hardware integration of SAR channels in the proposed method, based on the results of the initial detection of the object, a decision is made on additional location of the terrain sections corresponding to the primary detection data, after which the carrier makes a maneuver, as a result of which the carrier is brought out onto the trajectory, when which provide the location of these sections of the terrain in the side view mode, they probe these sections with a channel with high resolution, RGs are obtained and spatial positions of the PCA PCA are estimated during sounding, based on these data, the required XRD fragments are formed and the required object is detected, recognized and identified, and its geodetic coordinates are determined, and the location zones and sounding parameters and formed XRDs are selected with taking into account the results of the initial detection and change of the carrier path.

In PCA, the location zone is formed taking into account many factors, including based on the technical capabilities of the PCA and the aircraft and its flight path. This zone can significantly exceed the zone required, based on preliminary data on the position of the desired object. Therefore, on the radar images formed in the primary detection channels, a search zone is additionally formed based on preliminary data on the coordinates of the desired object and the selected location zone, and primary detection of the object is carried out in this zone.

When detecting and determining the coordinates of an object associated in its position with a source of radio emissions (IRI) with known distinctive properties, the formation of preliminary data on the coordinates of the desired object, and then the choice of the flight path of the aircraft, location and search zones for primary detection, is carried out by detecting and determining coordinates IRI using a passive locator mounted on an aircraft. To increase the accuracy of determining coordinates, this is done, for example, using synthesized passive antenna systems (SPAS), and the aircraft trajectory and synthesis time are selected taking into account the possibility of obtaining the maximum length of the effective aperture of the SPAS.

In order to increase the accuracy of assessing the position of the IRI, this assessment and the corresponding refinement of the object’s search zone in the primary SAR channel are also carried out after determining the location zone, the SAR goes into the active sensing mode of this zone and the formation of its radar image, and primary detection is carried out after the search zone is refined.

In order to reduce errors in determining the coordinates of the object and ensure the required accuracy during the synthesis of the SAR aperture with the help of NS aircraft, mutually independent estimates of the positions of the PCA PCA are repeatedly generated, and their number N ₁ for the synthesis interval is selected from the condition:

,

,

- дисперсия ошибок в знании положения ФЦА РСА, оцениваемая по нормали к траектории движения носителя, X_oб - дальность до лоцируемого участка местности, D_синт - протяженность синтезируемой апертуры,

- дисперсия допустимой ошибки в линейной привязке РЛИ к геодезическим координатам вдоль траектории ЛА (в азимутальном направлении).Where

- the variance of errors in the knowledge of the position of the PCA PCA, estimated according to the normal to the path of the carrier, X _about - the distance to the location of the terrain, D _synt - the length of the synthesized aperture,

- the variance of the permissible error in the linear reference of the radar to geodetic coordinates along the trajectory of the aircraft (in the azimuthal direction).

In order to more accurately assess the position of the PCA in the synthesis interval and, accordingly, to more accurately estimate the position of the object in geodetic coordinates, the portion of the PCA antenna path including the synthesis interval is described by some function with unknown parameters, further, based on navigation data on the position of the PCA PCA on this area, these parameters are evaluated, for example, by the maximum likelihood method, and, based on this function and its parameters, the position of the PCA PCA at each probe moment is specified tion in the range of synthesizing and then determine the coordinates of objects detected by radar data.

When there are of located terrain separate small objects with high reflectivity after the interval synthesizing N _synth soundings needed to form a radar image lines, detect one or more of the most intense signals reflected from objects on of located terrain and received SAR, evaluate phase changes of these signals for N _synth soundings and deviations of this change from the expected during the trajectory of the PCA PCA, corresponding to the data of the National Assembly, approximate these deviations I set, for example, a linear function with unknown parameters, evaluate these parameters, for example, using the maximum likelihood method, and, based on this, adjust the position estimates of the PCA PCA obtained from the data of the National Assembly and, based on these estimates, determine the coordinates found by Radar objects.

To partially compensate for errors in the assessment of the position of the object due to inaccurate knowledge of the position of the PCA, SAR self-focusing during the formation of X-ray radiation is carried out by entering the correcting phase in the complex envelopes of the signals for each i-probe, and first self-focusing is carried out in the long-wave channel, determining its correcting phase ψ _i and then in the short-wave channel, while in the short-wave channel, self-focusing is first evaluated at two correction biases previously introduced in this channel the signal at τ _1core and τ _2core , matched, for example, up to the temporal discretization of the signal in this channel, with the values ψ _{icor_dv} / (2πf ₀ ) and [ψ _{icor_dv} -2sign (ψ _{icor_dv} ) π] / (2πf ₀ ), _respectively where sign (x) means the operation of taking the sign of x, af ₀ is the carrier frequency of the probing signal, and for self-focusing, choose the offset at which the signal intensity after self-focusing is greater, and the corresponding correction bias τ _1core or τ _{2core is} used to correct the estimate of the position of the PCA PCA with the i-th sounding and, based on this, Calculation of geodetic coordinates of objects detected by radar images.

In order to increase the accuracy of determining the geodetic coordinates of the object, simplify the requirements for NS and improve the detection characteristics of the object and its recognition after sensing obtained, based on preliminary data, the location zone, the detection of the desired object in this zone, its identification and determination of its coordinates, additional sounding of this object one or more times when changing the angle of sounding due to a change in the path of the carrier in azimuth, and with each new location, based on the results tats of the previous soundings and the carrier path selected for this sounding, refine the location and search zones, detect and identify the desired object and evaluate its coordinates, and the resulting estimate of the geodetic coordinates of the object is determined by averaging the estimates of the coordinates of the object obtained at different angles of its location, s taking into account the errors of these estimates at different coordinates.

To achieve the greatest efficiency, the angle change is performed relative to the first sounding at an angle of 65 ° <α <115 °, and the number N _{2 of} independent estimates of the positions of PCA PCA for the synthesis interval in this case is chosen from the condition:

,

,

- дисперсия допустимой ошибки в линейной привязке РЛИ к геодезическим координатам.Where

- the variance of the permissible error in the linear binding of the radar to geodetic coordinates.

The technical result of the application of the proposed method consists, first of all, in the possibility of a phased and, at the same time, operational, that is, already in the process of locating or with a minimum delay, solution of the problem of search and detection of the desired object, its recognition and location using multi-channel multi-frequency PCA. In this case, a difference in reflecting properties from the background (forest, field, etc.) and detected objects at different frequencies and the possibility of interaction between operators of different channels are used. As a rule, in a low-frequency channel with a relatively low resolution, but with a high contrast of the desired object relative to the surrounding area, the probability of skipping this object is sharply reduced, although due to the complexity of correct recognition, the probability of false alarms can be quite high. But nevertheless, the use of a low-frequency channel for primary object detection and transmission of the received data to a high-resolution channel significantly (by orders of magnitude) reduces the load on a high-frequency channel with high resolution. In this channel, based on its WG, with some delay relative to the primary detection, radar images are formed with high resolution of those fragments of the terrain that were determined during the initial detection. When analyzing these fragments, due to high resolution, and therefore high information content and the likelihood of correct recognition of the required object, false alarms are quickly removed. Of all the radar fragments identified during the initial detection, only the desired remains in the high-resolution channel, which allows you to quickly detect an object and determine its location with high accuracy. When fulfilling a number of requirements for the NS, in particular, if the NS determines the position of the PCA PCA with errors not exceeding the resolution of the PCA, this method allows, firstly, to generate radar images sufficient to detect and recognize objects of a given type, and secondly, to detect and recognition of the desired object, and thirdly, to ensure the binding of these radar images to geodetic coordinates, that is, to ensure the determination of the geodetic coordinates of the detected object. It should be emphasized that in many cases the use of only a high-resolution channel virtually eliminates the possibility of operational detection of small objects.

As a rule, the possible range of changes in the parameters of the location zone for PCA is determined by its technical characteristics and operating conditions. For example, the minimum size of the location zone is usually limited and it can significantly exceed the search area due to preliminary data on the coordinates of the desired object. In this case, an additional technical result is obtained due to the formation of search zones on the radar in the channels of primary detection. Primary object detection is carried out in this zone, which can be significantly smaller than the PCA location zone, which significantly increases the efficiency and improves the detection characteristics.

An additional technical result can be obtained if the detected object is associated with a known type of radio emission. This radiation can be used to detect an object and generate preliminary data on its location using passive methods, and the efficiency of such a source can be significantly improved if a passive detection and determination of IRI coordinates is available on the aircraft along with SAR and to increase the accuracy of determining the coordinates of IRI A method for synthesizing passive antenna systems (SPAS). In this case, the detection of IRI is carried out at sufficiently large ranges and with sufficiently high accuracy, which allows us to generate preliminary data on the coordinates of the desired object in advance and optimize the flight path of the aircraft. In this case, the aircraft trajectory is chosen based on both obtaining the maximum extent of the effective aperture of the SPAS before the RSA enters active sensing mode and the beginning of the formation of radar data, and optimizing the operation of the RSA.

It should be borne in mind that if the location zone should be determined before the probing of this zone begins, then the search zone can be adjusted during the location of this zone, and even after that. Moreover, for the formation of radar images, it is necessary that the aircraft fly through that part of the trajectory that corresponds to the synthesized aperture, and therefore, the detection of the desired object in the search area can be carried out with some delay, which, in general, is determined by the storage time of the radar and radar data. This allows, in particular, during the formation of preliminary data due to the operation of the submarine, to continue its operation even after the formation of radar data, which will increase the accuracy of the submarine, significantly reduce the size of the search zone, sometimes several times, and will lead to a significant improvement in the detection characteristics.

An important technical result of the application of the method also lies in the fact that it stipulates a number of actions and conditions that provide a significant increase in the accuracy of the geodetic reference of the detected objects. This is the formation of mutually independent estimates of the positions of the FCA on the synthesis interval, and the choice of the accuracy of these estimates and their number, depending on the required accuracy of determining the position of the desired object. An important contribution to improving the accuracy of determining the coordinates of an object is made by the proposed methods for processing navigation data using estimates of changes in the phase synthesis interval of the most intense reflected signals, as well as multi-angle sensing of the same terrain. Moreover, in the case of changing the angle by an angle close to 90 degrees, the requirement for the number of independent measurements of the PCA PCA positions over the synthesis interval is greatly reduced.

List of drawings

Figure 1 shows the radar images of the terrain and various objects on it, including, such as agricultural machinery, in channels with a wavelength of 4 cm, 23 cm and 70 cm.

Figure 2 illustrates the concepts of effective aperture of SPAS D _synth and R _min. The effective aperture of SPAS can be defined as a chord of an arc of radius R _min limited by the SPAS formation sector.

Figure 3 shows the formation of preliminary data in the form of an ellipse of errors of the submarine when determining the coordinates of the IRI during the operation of the submarine on the interval D _synth prior to the PCA. In this FIG. shows the PCA location band as a band corresponding to preliminary data and technical capabilities of the PCA, the location zone as part of the band covering the zone of possible submarine errors, and the search zone corresponding to preliminary data.

Figure 4 explains the reduction of the search zone by extending the interval of operation of the submarine D _syntpl until the end of the PCA to probe the location zone and the formation of radar images.

Figure 5 shows the results of numerical calculations (simulations) of assessing the position of the object obtained for the case: R ₀ = 30 km, Y ₀ = 500 m, D _synth = 1 km, N = 100, σ _x = 0.5 m.

Figure 6 illustrates the ambiguity in determining the value of the correction phase during self-focusing.

The task of quickly detecting and recognizing the given objects is very difficult, since the information content of modern SARs is very high and it is difficult to quickly understand this flow of information. For example, for the successful detection and recognition of small-sized SAR resolutions in 1 m, the strip of the located area can be, for example, 4 km or more. That is, only in one line of objects is a resolution of the order of 1 m or less required and implemented in practice. There are SARs with a resolution of 10 cm. For radar images, the number of analyzed resolution elements in this case is 4000. In this case, the required rate of line formation, which is determined by the carrier’s flight speed and azimuth resolution, can be, for example, 1 kHz. It is difficult in this stream of information in the form of radar images with the specified permission to find and identify the required object. Currently, this is usually performed by the operator, but its capabilities are very limited. Gradually, automated systems appear, including those using algorithms for preliminary selection of areas for their further analysis by the operator. But practically today the problem is solved only for private situations. The task is complicated by the fact that in the cm-range, at which good resolution is achieved, the level of reflections from the area is high and it is difficult to detect an object with its low contrast with respect to the background.

At the same time, the contrast of the object's radar image relative to the background depends, in particular, on the carrier frequency of the probing signal of the SAR. Therefore, if there are several frequency channels in the SAR with different contrast of objects against the background of the surrounding area, in order to reduce the probability of missing the desired object and increase the efficiency and probability of its correct detection and recognition, this problem is solved in two stages. For primary detection, channels with high contrast are used. As a rule, these are channels with a lower carrier frequency of the probing signal. In some cases, channels are used for primary detection, including channels with a high carrier frequency operating in the overview mode, in which a radar image with reduced resolution is formed. But in any case, the results of primary detection are used in the SAR channel with a high carrier frequency, where the resolution is maximum. In this channel, one or several fragments of high-resolution detailed radar images are formed, the number, position and sizes of which correspond to the data of primary detection. The low resolution during initial detection and the difficulty of recognizing the desired object in this case require a low probability of skipping the detection object at a sufficiently high level of false alarms. But even with this, the areas of the area selected for primary detection that are transferred for secondary detection may, by the total number of detection elements in them, be several orders of magnitude smaller than the initial location zone during initial detection. The high resolution in the fragments used in the second stage of detection makes it possible to detect, recognize and identify the desired object with high probability.

In many cases, when a priori specifying the desired object and the terrain against which it should be detected, it is possible to calculate the expected contrast in different frequency channels in advance of probing the desired area. For example, the contrast of objects such as agricultural machinery against the background of arable land or a mowed field in the channels of 4- and 70-cm ranges varies greatly: they are indistinguishable in the 4-cm channel, but are clearly visible in the 70-cm channel, as confirmed by Fig. 1. Therefore, the primary detection of such objects should be done in the long-wave channel. On its radar image, areas are selected where preset objects are supposedly located, and detailed analysis and final detection and recognition are carried out using fragments of detailed cm-range radar data of selected areas. High resolution in this channel allows you to reject false alarms of primary detection and to find and recognize the desired object.

For operational detection, preliminary data on the position of the desired object are very important. If the SAR carrier is also equipped with a passive locator (PL), then when detecting and determining the coordinates of an object associated in its position with a source of radio emissions (IRI) with known distinctive properties, the formation of preliminary data can be carried out using this PL, which detects this IRI, identifies it, for example, by the nature of the emitted signal and determines its coordinates. When using SARs and submarines of one aircraft, it is possible to optimize the flight path of the carrier based on both the tasks of the submarines and the SARs, and thereby significantly increase the accuracy of preliminary data on the position of the target in a submarine and improve detection characteristics for the SAR.

The motion of the carrier along a well-known trajectory, which is necessary for the normal operation of the SAR side view, allows the use of synthesized passive antenna systems (SPAS) in PLs that use the spatiotemporal coherence of the IRI signal and its processing in the PL (see, for example, book P .A. Bakuleva "Radar Systems", publishing house "Radio Engineering", M., 2004). In this case, the trajectory of the aircraft and the synthesis time are selected on the basis of obtaining the maximum ratio of the effective aperture length SPAS D _syntpl and R _min (see figure 2) for the submarine and optimization of the operating conditions for the SAR. In this case, the effective aperture of the SPAS can be defined as a chord of an arc of radius R _min limited by the SPAS operation sector. Upon detection of IRI and its identification using PL, the path of the carrier is chosen so as to increase the effective length of the SPAS and the ratio D _syntf / R _min . To do this, in the simplest case, in accordance with figure 3, the submarine operates before the start of the PCA, making N _{deputy 1} sessions of receiving the IRI signal. In this case, it is necessary to take into account the time required to calculate the location zone and the required parameters of the SAR, and the need for the SAR side view to form a line of radar data of the offset of the beginning of its sounding by D _synt / 2 relative to the beam of this line. Based on the results of the submarine’s work, preliminary data are generated, on the basis of which the location band (see FIG. 3) and the location zone are determined as part of the strip covering the area of possible errors in determining coordinates during the formation of preliminary data. In this case, the location band should correspond to the technical capabilities of the PCA. Submarine errors are usually characterized by an ellipse of errors (see, for example, the book “Theoretical Foundations of Radar.” / Ed. By Ya. D. Shirman, Sov.radio Publishing House, Moscow: 1978, p. 504), and it defines the search area on the generated radar image.

The PCA task can be greatly simplified by changing the carrier route in order to reduce the location zone. For example, according to submarine data, the carrier performs a U-turn and flies along the long axis of the submarine error ellipse at a distance optimal for PCA operation. The location band narrows, and the location zone approaches the search zone, although, as already noted, there is some difference between the two zones, determined by the technical characteristics of the SAR, such as the ADC capacity, the number of processed samples in range in a special computer performing FFT when processing the input signal, and so forth

It should be noted that if the location zone should be determined before the start of sounding and the formation of XRD, since this determines the beginning of the sounding and parameters of the SAR, the search zone can be refined during the operation of the SAR and even after the formation of the SAR. This allows you to continue the work of the submarine and at the stage of operation of the SAR, and even after passing the SAR of the desired location zone. In this case, the number of sessions for receiving the IRI signal can be increased to N _zam2 , as shown in _Fig.4 . The accuracy of determining the coordinates of the IRI is significantly increased, since the effective length of the SPAS increases significantly. Using the generated radar image with a certain delay, refining the search zone on it according to the data obtained by the submarine as a result of this delay, it is possible to significantly increase the characteristics of operational detection, recognition and identification of a given object.

The requirements for the NS, which determines the coordinates of the PCA at each sounding, are due to two factors. First, the accuracy of determining the coordinates of the PCA should ensure the formation of radar images, which is formed by summing the reflected signals from each resolution element (each object) taken at different sensing periods in the synthesis interval. In this case, changes in the delays of these signals and their Doppler frequencies must be taken into account in accordance with a change in the range and angle of sight of this element in the synthesis interval. To summarize them, it is necessary that these signals coincide or at least partially overlap. In the latter case, a simple summation gives incoherent accumulation, and input, for example, due to self-focusing of the correcting phases, leads to a coherent summation of these signals. Only in this case can the radar image of the locality be formed. This means that errors in the knowledge of the position of this element for all soundings (or rather, their uncorrelated component) should not exceed approximately half the resolution on each coordinate axis associated with the radar image.

- дисперсии ошибок в знании положения антенны РСА, оцениваемых по нормали к траектории движения носителя, от Х_об - дальности до лоцируемого участка местности, от D_cинт - протяженности синтезируемой апертуры РСА и дисперсии

допустимой ошибки в положении объекта вдоль траектории полета носителя.Another factor determining the requirements for NS is the need to ensure high accuracy in the assessment of the geodetic coordinates of the detected object. Moreover, the requirements of these two factors do not coincide. For example, the quality of radar images is not affected by the presence of a systematic error in the knowledge of the position of the PCA, when the estimated trajectory of the PCA in the synthesis interval is shifted parallel to the true trajectory. But from the point of view of assessing the position of the object, this error is unacceptable, since it cannot be compensated and goes directly to the error of determining the coordinates of the object. The correlated component of errors in assessing the positions of the PCA, that is, an error that smoothly changes over the synthesis interval, is also undesirable, since it leads to large errors in the position of the object in the azimuthal plane (along the path of the carrier). Thus, independent estimates of the coordinates of the PCA are required, and their number in the synthesis interval depends mainly on

- variance of errors in the knowledge of the position of the SAR antenna, estimated normal to the trajectory of the carrier, from X _about - range to the positioned area, from D _synth - the length of the synthesized aperture of the SAR and dispersion

permissible errors in the position of the object along the flight path of the carrier.

Errors in determining the position of the detected object from the two main axes of the error ellipsoid — the Y and X axes — can be estimated, for example, for a point object, if we assume that the true positions of the PCA PCA on the synthesis interval lie on one straight line coinciding with the Y axis. Errors in the knowledge of the PCA, on the synthesis interval, on average, can be approximated by shifting this straight line relative to the true parallel to itself by ΔX and its rotation about the Y axis by an angle α, approximately equal, in view of its smallness, tg (α). In this case, the shift ΔX is equivalent to a systematic error and leads to a shift along the X axis, and the antenna tilt by angle α to the influence of a correlated error, which leads to a shift of the radar image along the Y axis.

You can apply the maximum likelihood method to determine the algorithms for calculating ΔX and α and the Fisher matrix to find the variances of these estimates. In this case, the error estimation of the position of the radar detector point to the true position of the antenna in the presence of random errors in the knowledge of the position of this antenna (at N points), changing according to the normal law, can be obtained analytically if we approximate these errors by changing the position of the ruler: its offset X ₀ X axis and a change in the slope by an angle α relative to the Y axis. The logarithm of the likelihood function for this case (accurate to the terms that are not significant from the point of view of estimating binding errors) can be written as:

- дисперсия этих оценок, b=tg(α), а Y_R - шаг между точками линейки синтезированной антенны. Полагаем, что ошибок в знании положения антенны по оси Y нет, так как можно показать, что влияние их незначительно.where X is the vector of estimates x _{i of the} position of the PCA at the ith step along the X axis, and the average value of x _i is 0, and

is the variance of these estimates, b = tg (α), and Y _R is the step between the points of the line of the synthesized antenna. We believe that there are no errors in knowing the position of the antenna along the Y axis, since it can be shown that their influence is insignificant.

In accordance with (2), the Fisher matrix, which is determined by the average value of the second partial derivatives of L with unknown parameters X ₀ and b with a minus sign, has the form:

The determinant of the matrix J

,

,

and, given that the variance of the most effective estimate of the ith parameter is

it can be obtained that the variance of the most effective estimate of X ₀ is determined by the formula:

and the variance of the most effective estimate b

Based on an effective estimate of b, we can find the error of the shift of the radar image in azimuth at a distance of R ₀

For example, at R ₀ = 30 km, D _synt = 1 km, N = 100 and σ _x = 0.5 m in accordance with (5) ... (7) σ _az = 5 m, and σ _{eff x} = 0.1 m.

The same errors in the binding of radar images to the antenna trajectory can be estimated numerically. We assume, as before, that the aircraft flies in a straight line passing along the Y axis at X = 0. Moreover, to synthesize one line of radar data, the locator performs N soundings. At each sensing point with coordinates [x _i ; at _i ] (i = 1, 2, ..., N) the aircraft NS with some error determines the position [x _i ^* ; at _i ^* ], and from this the calculation of the distance R _i to the given point of the radar image [x _t ; at _t ]. Required based on R _i and coordinates with an error [x _i ^* ; y _i ^* ], calculate the position of the located point of the radar image [x _t ^* ; at _t ^* ].

Coordinates with an error are distributed according to the normal law [x _i ^* = N (x _i , σ _x ); y _i ^* = N (y _i , σ _y )]. Coordinates of the given radar point [x _t ^* ; y _t ^* ] is calculated using the least squares method:

argmin (S (x _t ^* , y _t ^* )), where S = Σ _{i = 1..N} (R _i -R _i ^* ) ² ,

where R _i ^{* is the} distance from [x _i ^* ; at _i ^* ] to [x _t ^* ; at _t ^* ].

Numerical calculations are carried out for the case considered earlier:

R ₀ = 30 km, D _synth = 1 km, N = 100, σ _x = 0.5 m. Figure 5 shows the estimates of the position of the object obtained with its true position Y ₀ = 500 m

As can be seen from Fig., Σ _RLiu ≈5 m and σ _RLIh = 0.05 m.

. Учитывая, что сама дисперсия

не может быть большой (иначе не сформируется РЛИ), то смещение РЛИ будет незначительным. Средние значения tg(α) и ошибки по азимуту также равны 0, а дисперсия этой ошибки может быть уменьшена до требуемого значения за счет выбора R₀, D_синт и N.Thus, both analytical and numerical analysis of the influence of random uncorrelated errors among themselves give approximately the same result. In this case, the random displacement along the X axis is on average equal to zero, and the variance of this displacement is approximately N times smaller than the variance of the estimate of the position of the PCA

. Given that the variance itself

cannot be large (otherwise the radar image will not form), then the displacement of the radar image will be insignificant. The average values of tg (α) and azimuth errors are also equal to 0, and the variance of this error can be reduced to the desired value by choosing R ₀ , D _synth and N.

As can be seen from the above, the azimuthal error prevails when estimating the coordinates of the detected object. Therefore, we can conclude that in order to achieve the required accuracy in determining the coordinates of the NS carrier object during the synthesis of the aperture, the SAR must repeatedly generate mutually independent estimates of the positions of the PCA PCA, and their number N ₁ for the synthesis interval is selected from the condition:

.

.

The requirements for NS can be significantly reduced, and the accuracy of determining the coordinates of the object can be significantly increased if sounding obtained, based on preliminary data, the location zones are carried out at least twice when changing the angle of sounding due to a change in the trajectory of the aircraft in azimuth. It is important that the change in angle is as close as possible to 90 degrees. With each new location, based on the data obtained from previous soundings and the path of the carrier selected for the new location, the location zone and the search zone are refined, the desired object is detected and identified and its coordinates are determined, and the resulting geodetic coordinates of the object are found by averaging the coordinates, obtained at each angle, taking into account the variances of the estimates of these coordinates for each coordinate. In the simplest case, for example, when changing the angle of 90 degrees, given that the variance of the estimates of the coordinates of the object along the path of the carrier (in azimuth) is significantly, by orders of magnitude, greater than the variance of estimates of its coordinates in range (normal to the path of the carrier), you can use of each angle, only estimates of coordinates in range and do not take into account estimates in azimuth at all.

In addition, the number N _{2 of} independent estimates of the positions of the PCA PCA for the synthesis interval when changing the angle by an angle α close to 90 degrees is selected from the condition

,

,

- дисперсия ошибок в знании положения ФЦА РСА, оцениваемых по нормали к траектории движения носителя при каждом ракурсе зондирования. Полагается, что дисперсия ошибок в знании положения ФЦА вдоль траектории носителя мала, по крайней мере, не превышает

, и в этом случае влияние этих ошибок также мало. Можно показать, что при меньшем изменении ракурса ошибка по нормали к траектории возрастает пропорционально 1/cosα, и, если, исходя из практики, положить, что допустимо возрастание этой ошибки на 10%, то должно выполняться условие 65°<α<115°.which follows from expression (5). Wherein

- the variance of errors in the knowledge of the position of the PCA PCA, estimated along the normal to the path of the carrier at each angle of sounding. It is believed that the variance of errors in the knowledge of the position of the PCA along the carrier path is small, at least not exceeding

, and in this case, the influence of these errors is also small. It can be shown that with a smaller change in angle, the error along the normal to the trajectory increases in proportion to 1 / cosα, and if, based on practice, it is assumed that this error is allowed to increase by 10%, then the condition 65 ° <α <115 ° must be fulfilled.

NS data can be improved by their additional processing, based on the particular tasks of determining the geodetic coordinates of a detected object. As already noted, the formation of radar images requires current assessments of the FCA, and the adjustment of the assessment of the position of the object is carried out after the detection of this object and can even be carried out with some delay relative to the moment of detection. In this case, to estimate the trajectory of the PCA movement on the synthesis interval, one can use not only the NS data for this interval and the data preceding it, but also subsequent data. In this case, the trajectory of the PCA in the interval is described by some function with unknown parameters and, based on the navigation data on the position of the PCA of the PCA in this section, these parameters are evaluated, for example, by the maximum likelihood method. Further, based on this function and its parameters, the position of the PCA PCA at each moment of sounding in the synthesis interval is clarified and then the coordinates of the objects detected by X-ray radiation are refined.

Taking into account the nature of the autopilot’s action when setting the carrier to linear motion in a straight line, its true trajectory, like the PCA PCA trajectory, can be described, for example, by the sum of several sinusoids with unknown frequencies, amplitudes and initial phases and some straight line. Having written down the logarithm of the likelihood function, based on the selected function and estimates of the coordinates of the PCA obtained by the NS, the unknown parameters of this function are determined, for example, by the maximum likelihood method. In some situations, this approach can significantly reduce the systematic and random components of errors in determining the position of the PCA in the synthesis interval and, as a result, errors in determining the coordinates of the object.

NS errors can be partially compensated by analyzing the reflected signals in the synthesis interval. In many cases, for example, during self-focusing, when conducting soundings necessary for the formation of radar images, one or more of the most intense signals reflected from objects on the located area and received by the SAR are detected. Self-focusing is carried out using these signals, selecting their phases (or delays) and achieving their coherent summation over N synthesized _probes in the synthesis interval. These signals are also used to correct the data of the National Assembly. For this, the phase changes of the selected signal (s) for N soundings and the deviations of this change from the expected one are estimated based on the calculated trajectory of the PCA PCA corresponding to the data of the National Assembly. The resulting deviation in the phase change characterizes the mismatch between the calculated and true trajectories. Next, these deviations are approximated by a specified, for example, linear function with unknown parameters, these parameters are estimated, for example, using the maximum likelihood method, and, based on this, the position estimates of the PCA PCA obtained from the NS are corrected and, accordingly, the coordinates estimated from Radar objects.

Another possibility of using the input information for adjusting the data of the NS is also associated with self-focusing. As already noted, in the formation of radar images to achieve its high quality, they strive to ensure coherent summation of the reflected signals obtained for all N soundings in the synthesis interval for each resolution element. In practice, this is achieved through the use of self-focusing algorithms. There are various methods of self-focusing, including a method based on inputting into the complex envelope of the signal received during the i-th sounding a correcting phase ψ _iкop obtained, for example, based on the criterion of reaching the maximum of one of the most intense reflected signals. However, in this case, the phase-matching of the summed signals reflected from the same object is achieved, but the signal position is not corrected and, therefore, the error in estimating the position of the object is not reduced due to inaccurate knowledge of the position of the PCA.

However, the knowledge of the corrective phase ψ _{icor is} equivalent to the knowledge of the corrective delay, since this delay is the main reason for the appearance of this phase. In this case, the correction delay can be calculated as τ _icor = ψ _icor / 2πf ₀ , where f ₀ = c / λ, and c is the speed of light. Since the estimation of the correcting phase is carried out accurate to an integer 2π, with such self-focusing, the error in the knowledge of the position of the PCA is unambiguously estimated within the wavelength λ. Accordingly, the correction of this error can be carried out by a value not exceeding λ.

In multichannel SAR, the error in the NS data on the position of the PCA should be consistent with the resolution in the channel with the best resolution, that is, in the SAR channel with a high carrier frequency. In each SAR channel, the value of its resolution, as a rule, significantly exceeds the wavelength of this channel. Therefore, it makes no sense to adjust the delay using the corrective phase of its own channel. But you can use the phase obtained in the long-wave channel, that is, in the channel with a lower carrier frequency, to adjust the delay in the channel with a high carrier frequency. So, for example, at a wavelength in the channel with a low carrier frequency λ _dv = 70 cm, its corrective range correction R _{icor_dv} can reach 35 cm, which is comparable with the resolution (of the order of 1 m) in the short-wave channel with λ _q = 3 cm and signal bandwidth of the order of 200 MHz. Assuming that the navigation error in determining the FCA of two frequency channels is the same and taking into account that R _{icore_dv} = τ _{icore dv} / 2, we can calculate the correcting delay τ _{icore_dv} = ψ _{icore_dv} λ _dv / 2πs from the correcting phase of the long-wave channel, and then and corrective range correction R _iкop = R _{iкор_дв} .

However, the determination of the corrective phase using only the input signals is ambiguous. This can be shown using Fig.6, which shows two options for the location of the signals of the i-th and (i + 1) -th probe clocks when summing them. In option 1 (i + 1) -th signal is ahead of the signal of the i-th probe cycle. In option 2, the signal of the (i + 1) -th clock lags behind the i-th signal. But the phase difference meter, which has a phase measurement range from -π to π, in both cases will show the estimate ψ _i = 2πcτ _i / λ. Therefore, to eliminate the uncertainty, self-focusing is first carried out in the long-wave channel, determining its correcting phase ψ _{icor_dv} , and then in the short-wave channel. In this case, in the short-wavelength channel, self-focusing is first evaluated for two correcting signal shifts by _τ1core and _τ2cori previously entered in this channel, which are matched, for example, up to the temporal sampling of the signal in this channel, with the values respectively ψ _{icor_dv} / (2πf ₀ ) and [ψ _{ikor_dv} -2sign (ψ _{ikop_dv} ) π] / (2πf ₀ ), where sign (x) means the operation of taking the sign of x, af ₀ is the carrier frequency of the probe signal. For self-focusing, choose the offset at which the signal intensity after self-focusing is greater, and the corresponding corrective offset τ _1cori or τ _{2copi is} used to correct the estimate of the position of the PCA PCA with (i + 1) -m probing and, based on this, correct the geodetic coordinates of the detected by radar objects.

Claims (11)

1. A method for detecting and determining the coordinates of a desired object, including the use of a side-scan radar with a synthesized aperture (PCA) mounted on a carrier in the form of an aircraft (LA), the formation of preliminary data about the desired object and its coordinates, determination based on these data and characteristics the selected aircraft and SAR flight paths of the carrier and the location zones for SAR, the exit of the aircraft to a given trajectory and the location of these zones using SAR with simultaneous determination using navigation systems s (NS) of the aircraft and storing the spatial position of the phase centers of the antennas of the SAR at each sounding, for example, their geodetic coordinates, obtaining at the output of the SAR receiver radio holograms (WG) and their storage, the formation of a radar image (RLI) of the specified location zones due to WG processing for the synthesis interval taking into account the spatial positions of the FCA and the use of self-focusing methods, detection of an object on this XRD, its recognition and determination of its position in the screen coordinate system, followed by determining the geodetic coordinates of the object, characterized in that K≥2 SAR channels operating in different frequency ranges are used, and the resolution in the channel with the highest carrier frequency is coordinated with the dimensions of the detected object, the NS is selected from the condition that the errors of the NS when determining the positions of the PCA of the RSA do not exceed the resolution of the SAR, and when locating, the object is first detected in the location zone, choosing for this the SAR channels with high contrast of the signal reflected from the target object to the background terrain, and the results of primary detection are used in a SAR channel with a higher resolution, in which fragments of detailed radar images are generated, the number, position and sizes of which correspond to the data of primary detection, and the desired object is detected, recognized and identified on these fragments, and its location is determined in screen coordinate system, and then the coordinates of the object are recalculated into geodetic coordinates, while the screen coordinate system is linked to the geodetic coordinate system based on estimates of the geodetic coordinates of the PCA PCA of this channel. 2. The method according to claim 1, characterized in that according to the results of the initial detection of the object, a decision is made on additional location of the terrain sections corresponding to the data of the primary detection, after which they carry out a maneuver by the carrier, as a result of which the carrier is brought out onto the trajectory at which the locations of these sections are provided terrain in the side-view mode, they probe these areas with a high-resolution channel, obtain RGs and evaluate the spatial positions of the PCA PCA during sounding, based on Using these data, the required radar image fragments are formed, and they are used to detect, recognize and identify the desired object, and its geodetic coordinates are determined, and the location zones and sounding parameters and generated radar data are selected taking into account the results of initial detection and change of the carrier path. 3. The method according to any one of claims 1 or 2, characterized in that the radar generated in the primary detection channels additionally form a search zone based on preliminary data on the coordinates of the desired object and the selected location zone, and primary detection of the object is carried out in this zone . 4. The method according to any one of claims 1 or 3, characterized in that when detecting and determining the coordinates of the object associated in its location with a source of radio emission (IRI) with known characteristics, the formation of preliminary data on the coordinates of the desired object, and then the selection of the flight path LA, location zones and search zones for primary detection are carried out by detecting and determining the coordinates of the IRI using a passive locator mounted on the aircraft using, for example, a synthesized passive antenna Istemi (SPAS), wherein the LA and the synthesizing time in view of the trajectory is selected to maximize the extent of the effective aperture SPAS. 5. The method according to claim 4, characterized in that the assessment of the position of the IRI and the refinement of the object search zone in the primary PCA detection channel associated with this assessment are carried out after determining the location zone, the PCA entering the active sensing mode of this zone and forming its radar image, and primary detection is carried out after refinement of the search area. 6. The method according to claim 1, characterized in that during the synthesis of the aperture of the SAR using NS LA repeatedly form mutually independent estimates of the positions of the PCA PCA, and their number N ₁ for the synthesis interval is selected from the condition

,
Where

- the variance of errors in the knowledge of the position of the PCA PCA, estimated along the normal to the path of the carrier, X _rev is the distance to the located area relative to the path of the carrier, D _synt is the length of the synthesized aperture,

- the variance of the permissible error in the linear binding of the radar to geodetic coordinates along the trajectory of the aircraft. 7. The method according to claim 1, characterized in that the portion of the trajectory of the PCA PCA, including the synthesis interval, is described by a certain function, the parameters of which are determined on the basis of the NS data on the position of the PCA PCA in this section, for example, using the maximum likelihood method, and Based on this function and its parameters, the position of the PCA PCA at each moment of sounding in the synthesis interval is specified and then the geodetic coordinates of the objects detected by the X-ray radar are determined. 8. The method according to claim 1, characterized in that during the synthesis interval N _synth soundings necessary to form one line of the radar image, one or more of the most intense signals reflected from objects on the located area and received by the SAR are detected, phase changes of these signals for N _synth soundings and deviations of this change from the expected during the trajectory of the PCA PCA corresponding to the data of the NS aircraft, approximate these deviations by a specified, for example, linear function with unknown parameters, estimating These parameters are determined, for example, using the maximum likelihood method, and, based on this, the position estimates of the PCA PCA obtained from the NS are corrected, and the coordinates of objects detected by the radar image are determined from these estimates. 9. The method according to claim 1, characterized in that any two channels are used (K = 2), and the PCA self-focusing is carried out by entering the correcting phase in the complex envelopes of the signals for each i-th sounding, and first, self-focusing is carried out in a channel carrying a frequency which is lower than the carrier frequency of the other channel, determine its phase correction ψ _{ikor_dv,} and then in a channel with a higher carrier frequency, with a channel with a higher carrier frequency initially assess the self-focusing when two pre-administered to the Nala corrective bias signal to τ and τ _{ikor_dv 2kori} agreed upon, e.g., up to a time-sampled signal in this channel, with the values respectively _{ikor_dv} ψ / (2πf ₀₎ and [ψ _{ikor_dv} -2sign (ψ _{ikop_dv)} π] / (2πf ₀ ), where sign (x) means the operation of taking the sign of x, af ₀ is the carrier frequency of the probing signal, and for self-focusing, choose the offset at which the signal intensity after self-focusing is greater, and the corresponding correction bias τ _{icor_dv} or τ _{2cori is} used to correct the estimate the position of the PCA PCA with the i-th probe In this case, and based on this, they calculate the geodetic coordinates of objects detected by radar data. 10. The method according to claim 1, characterized in that after sensing the location zone obtained according to preliminary data, detecting the desired object in this zone, identifying it and determining its coordinates, additional sounding of this object is carried out one or more times when changing the viewing angle due to change the path of the carrier in azimuth, while with each new location, the zones of location and search are specified, based on the results of previous soundings and the path of the carrier selected for this sounding, then lyayut detection and identification of the search object and an assessment of its origin, and the resulting assessment of geodesic coordinates of the object is determined by averaging the results of evaluations of object coordinates obtained at different angles of locating it, given the coordinates for various errors in these assessments. 11. The method according to claim 10, characterized in that the change of angle is performed relative to the first sounding at an angle of 65 ° <α <115 °, and the number N _{2 of} independent estimates of the positions of the PCA PCA for the synthesis interval in this case is selected from the condition

,
Where

- the variance of the permissible error in the linear binding of the radar to geodetic coordinates.

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