WO2012160509A1

WO2012160509A1 - Determining a spatial direction of a radar antenna

Info

Publication number: WO2012160509A1
Application number: PCT/IB2012/052553
Authority: WO
Inventors: Dekel Tzidon; Yehoshua Carpassi
Original assignee: Elbit Systems Ltd.
Priority date: 2011-05-22
Filing date: 2012-05-22
Publication date: 2012-11-29
Also published as: IL213045A0

Abstract

A method of extracting operational features of a radio frequency (RF) radar or of an antenna thereof, usable for simulating virtual targets for the radar is provided herein. The method includes the following steps: sampling in real-time RF signals transmitted by the radar antenna and received by at least three RF sensors located proximal to the antenna; and using pre-generated calibration data that correlates pre- generated samples of RF signals with operational features of the radar or the antenna, to extrapolate the operational features comprising at least one of: spatial direction of the antenna; and mode of operation of the radar respectively, based on the real-time sampled RF signals.

Description

DETERMINING A SPATIAL DIRECTION OF A RADAR ANTENNA

BACKGROUND

1. TECHNICAL FIELD

The present invention relates generally to a system for determining a spatial direction of a radio frequency (RF) radar antenna, and more specifically to a virtual target simulator utilizing such a system.

2. DISCUSSION OF THE RELATED ART

In the field of Radar operation, the need for testing and practicing radar operation in real environment is recognized. Doing so, by means of independent system with no integration with the real Radar, is still a challenge. Current technologies include connecting the test or practice equipment onto the inner circuits of the radar, for example by connecting to a control bus so that direction of the antenna and the mode of operation of the radar may be monitored directly from the radar's circuits.

BRIEF SUMMARY

Some embodiments of the present invention provide a Virtual Target Injection System that can work in real environment. The system preferably injects virtual targets to stimulate a Radar system. Optionally and preferably the system also detects the antenna's direction. Optionally and preferably the system detects the Radar's mode of operation.

In various exemplary embodiments of the invention the system is a standalone system devoid of any physical integration with a real Radar system. Thus, embodiments of the present invention overcomes the disadvantages of the prior art systems which necessitate physical integration with the radar circuitry.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

Implementation of the method and/or system of embodiments of the invention can involve performing or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of embodiments of the method and/or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.

For example, hardware for performing selected tasks according to embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of method and/or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and/or data and/or a non-volatile storage, for example, a magnetic hard- disk and/or removable media, for storing instructions and/or data. Optionally, a network connection is provided as well. A display and/or a user input device such as a keyboard or mouse are optionally provided as well.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

Figure 1 is a high level flowchart block diagram illustrating the process, according to some embodiments of the present invention;

Figures 2, 3, and 4 are flowchart diagrams representing detailed process of pre- building the Lookup tables, according to some embodiments of the present invention:

Figure 5 is a high level flowchart diagram representing the system in operational mode; detecting the antenna direction and Radar's mode, calculating the response signals according to the Virtual Target Simulation and transmits these signals back to the radar's antenna, according to some embodiments of the present invention; and

Figure 6 is a schematic block diagram illustrating an aspect of a system according to some embodiments of the present invention, in which RF transceivers are positioned near the antenna's base.

DETAILED DESCRIPTION

With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is applicable to other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

The present invention, in embodiments thereof, provides a method of extracting operational features of a radio frequency (RF) radar or of an antenna thereof, usable for simulating virtual targets for the radar. The method starts off with the stage of sampling in real-time RF signals transmitted by the radar antenna and received by at least three RF sensors located proximal to the antenna. Then the method goes on to the stage of using pre-generated calibration data that correlates pre-generated samples of RF signals with operational features of the radar or the antenna, to extrapolate the operational features. These operational features may include either spatial direction of the antenna, a mode of operation of the radar respectively or a combination thereof. The operation features are extrapolated based on the real-time sampled RF signals in manners as will be detailed below.

Figure 1 is a high level flowchart illustrating one embodiment of the Virtual Target Injection System. As shown in the flowchart, the system determines the Radar mode and antenna direction (200), calculates the virtual target appropriate response (300) and transmits back virtual target's RF signals towards the Radar's antenna (400)

Referring to Figure 6, the Virtual Target Injection System (600) may include three or more RF sensors (606) located behind the Radar's antenna (10) by its base (20). The system further comprises a controller (608) running the Virtual Target Simulation sub-system, lookup tables - LUT Ά', 'B' and 'M' (609) and Digital Radio Frequency Memory - 'DRFM' (610).

For clarity of presentation, system having four RF sensors (606) will now be described. It should be appreciated that it is not intended to limit the scope of the present invention to four sensors and that any number of sensors (e.g., larger than four) may be used. Some embodiments with more than four sensors are described below.

In some embodiments, each sensor is placed behind its relevant antenna quadrant, dividing the volume near the antenna base into four sectors. The system uses the side lobes readings sampled on the sensors and the corresponding values on the prebuilt databases preferably arranged as lookup tables LUT (609) to estimate the direction of the Radar's main lobe. Thus, enabling Virtual Target Simulation Sub-system to transmit target signals at corresponding antenna positions, mimicking true radar reception of targets. The same system may include one or more transmitting antennas for virtual targets injection. The location of the transmitting antenna is preferably at the sensors location and preferably with the same sensor's receiving antenna, hence sensor- transceivers. Once the direction of the radar's antenna estimated, the Virtual Target Injection System may transmit the target's RF response at some amplitude mixture following those prebuilt lookup tables (609), thus allowing the radar to display virtual targets at their simulated locations without any physical hardware intervention to neither the Radar's antenna, nor the Aircraft's MaxBus communication system.

Direction of the Radar's antenna optionally and preferably includes both the Azimuth and Elevation angles referenced to the base of the antenna. When the radar is not stationary, the direction of the antenna optionally and preferably takes into account the orientation of the platform that comprises the radar. In these embodiments, the antenna direction vector is added to the platform direction vector.

Normally, the operation the radar's antenna perform two main tasks: (i) scanning the area and transmitting RF pulse towards desired direction (main lobe directed on the antenna's normal). On each direction of the radar's antenna, the radar transmits an RF pulse, wait to receive an echo signal from the target and then move on to the next direction of the scanning pattern. The sensor-transceivers may be located at the radar' s antenna base or just behind it to receive side lobe signals every time the radar transmits its main lobe RF signal. Since the side lobes are side effect of the main lobe transmission, it may have different readings of intensities (amplitudes) on different positions of radar's antenna on each of the four or more sensors.

Figure 2 illustrates a procedure useful for building a lookup table (referred herein as "LUT") which can record and save the amplitude values of the antenna transmission lobes at a series of angles along the antenna bars. The prebuilt database is preferably arranged as lookup tables LUT 'A' may have an entry for each of at least some of the radar antenna, wherein each entry correlates between the antenna direction and all sensors readings. The process of building LUT 'A' comprises activating the Radar on a specific mode of operation, preferably scan mode (102), and then sample and save the sensors values for each antenna direction (104). When too many entries of LUT 'A' are non-unique, it may cause target location errors. The probability for multiple antenna directions with same sensors readings is optionally and preferably achieved by changing the location of the sensors and/or adding one or more additional sensors, resulting a LUT 'A' correlating RF readings with antenna's main lobe direction.

Figure 3 illustrates a procedure useful for building a lookup table, LUT M. In general the process is similar to the process of pre-build LUT 'A' with the exception that the data recorded are different. Thus, in some embodiments of the present invention for each of at least some of the antenna directions and for each of at least some of the radar modes of operation (114) the system records data indicative of the radar mode, to build LUT 'M' correlating RF readings with Radar's mode of operation (116). Knowing the radar's mode of operation may support the system to better estimate the direction of the antenna based on the previous direction and scanning pattern. Radars may have different modes of operation to support different needs of detection and/or tracking: e.g. Range While Search (RWS), Velocity Search (VS), Single Target Track (STT), Track While Scan (TWS), lobe On Receive Only (LORO), Air Combat Mode (ACM), Ground Moving Target Indication/Ground Moving Target Track (GMTI/GMTT), Air to Ground Ranging (AGR), Synthetic Aperture radar (SAR) and more. Each of the modes may use different radar technology and may differ in Antenna scan patterns e.g. number of bars, scan width, scan center etc. or RF signal intensity or Pulse Repetition Frequency (PRF - determines the maximum target range and maximum Doppler velocity that can be accurately determined by the radar). In some modes such as LORO (lobe On Receive Only) Mode, STT (single Target Track) Mode or similar, the Radar changes its mode of operation to improve tracking accuracy. In these modes, the Radar divides its antenna into two halves or four quadrants and compares the levels of return signals to determine the direction of the target. Upon any amplitude differences, the radar system can 'decide' where to move the antenna to get balanced readings from the two halves or four quadrants respectively, thus rapidly aiming the antenna towards the target, providing tracking and locking mechanisms.

Figure 4 illustrates a procedure useful for building a lookup table, LUT B. The procedure comprises activating the Radar on a specific mode of operation, preferably, but not necessarily, some kind of STT (single Target Track) Mode (122). Then, for each of at least some directions of the antenna main lobe (124), the controller (608) mimics the same amplitudes as recorded in LUT 'A' (126) and re-transmit them back towards the Radar's antenna from the sensor-transceivers (606). The Radar readings of the target direction and distance are then compared with the simulated target direction and distance. If the readings are not equal, the Radar readings may drift from the desired direction and the entries of LUT 'A' are preferably fine-tuned creating LUT 'B' (128). The fine-tune process preferably continues until some stopping criterion is met. For example, the fine-tune process can continue until LUT 'B' values deceive the Radar as if a real target is there. In operation, as the antenna reaches a position where a virtual target should be (Interpolation of the LUT A), values from LUT 'B' may determine signal intensities to be transmitted using several (e.g., all) sensor-transceivers simultaneously to simulate an accurate position of the virtual target in the real Radar System.

In reference to Figure 5, once the radar transmits its main lobe pulses, along with the side lobes signals, the sensors samples a mixture of the signals (202). Following the pre-build LUT A, an interpolation subsystem (Either SW or HW) may use some kind of a logic mechanism (e.g. linear, fuzzy etc.) from LUT 'A' values to attempt and determine the radar's pointing direction in both Azimuth and Elevation and from LUT 'M' to determine the Radar's mode of operation (204).

As the antenna's direction and/or mode determined, the Virtual Target Simulation Sub-system, that handles the virtual targets in the virtual world, decides whether the Radar should detect the virtual target (302). In case there is no target on the Radar's line of sight, the system optionally and preferably keeps silent while the Radar antenna moves to its new direction (or mode). The system may stay in this loop (202 - 302) until a virtual target will "show up" in front of the Radar's main lobe, moving to the next step (402). Since the virtual target is virtually in sight of the Radar, the Radar gets the return signal from that target in order to detect and track it properly. Thus the Virtual Target Injection System of the present embodiments manipulates the Radar signal and sends it back towards the Radar's antenna. The RF signal may be sampled (202) by the RF sensors (606) and saved on the Digital Radio Frequency Memory (610). The Virtual Target Injection System running on the controller (608) may alter (304) signal's intensity, Doppler, and timing, in accordance to the simulated virtual target characteristics: type of target (i.e. Radar Cross Section 'RCS'), speed & direction, distance etc., finally the altered signal may be transmitted towards the Radar's antenna by the sensor-transceivers utilizing LUT 'A' or 'B' (402). As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit," "module" or "system." Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may be utilized to implement the look up tables disclosed herein. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wire-line, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). Aspects of the present invention are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

The aforementioned flowchart and diagrams illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In the above description, an embodiment is an example or implementation of the inventions. The various appearances of "one embodiment," "an embodiment" or "some embodiments" do not necessarily all refer to the same embodiments.

Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment.

Reference in the specification to "some embodiments", "an embodiment", "one embodiment" or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the inventions.

It is to be understood that the phraseology and terminology employed herein is not to be construed as limiting and are for descriptive purpose only.

The principles and uses of the teachings of the present invention may be better understood with reference to the accompanying description, figures and examples.

It is to be understood that the details set forth herein do not construe a limitation to an application of the invention.

Furthermore, it is to be understood that the invention can be carried out or practiced in various ways and that the invention can be implemented in embodiments other than the ones outlined in the description above.

It is to be understood that the terms "including", "comprising", "consisting" and grammatical variants thereof do not preclude the addition of one or more components, features, steps, or integers or groups thereof and that the terms are to be construed as specifying components, features, steps or integers.

If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

It is to be understood that where the claims or specification refer to "a" or "an" element, such reference is not be construed that there is only one of that element.

It is to be understood that where the specification states that a component, feature, structure, or characteristic "may", "might", "can" or "could" be included, that particular component, feature, structure, or characteristic is not required to be included.

Where applicable, although state diagrams, flow diagrams or both may be used to describe embodiments, the invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.

Methods of the present invention may be implemented by performing or completing manually, automatically, or a combination thereof, selected steps or tasks.

The descriptions, examples, methods and materials presented in the claims and the specification are not to be construed as limiting but rather as illustrative only.

Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined.

The present invention may be implemented in the testing or practice with methods and materials equivalent or similar to those described herein.

Any publications, including patents, patent applications and articles, referenced or mentioned in this specification are herein incorporated in their entirety into the specification, to the same extent as if each individual publication was specifically and individually indicated to be incorporated herein. In addition, citation or identification of any reference in the description of some embodiments of the invention shall not be construed as an admission that such reference is available as prior art to the present invention.

While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention.

Claims

CLAIMS What is claimed is:

1. A method of extracting operational features of a radio frequency (RF) radar or of an antenna thereof, usable for simulating virtual targets for the radar, the method comprising:

sampling in real-time RF signals transmitted by the radar antenna and received by at least three RF sensors located proximal to the antenna; and

using pre-generated calibration data that correlates pre-generated samples of RF signals with operational features of the radar or the antenna, to extrapolate the operational features comprising at least one of: spatial direction of the antenna; and mode of operation of the radar respectively, based on the real-time sampled RF signals.

2. The method according to claim 1, wherein the RF sensors are further configured to transmit RF signals and wherein the method further comprises injecting RF signals by the RF sensors into the antenna, wherein the injected signals mimic a radar echo from a specified virtual target.

3. The method according to claim 1, wherein the pre-generated calibration data is stored on one or more look up tables (LUT).

4. The method according to claim 3, wherein at least one of the LUT is generated by: a) activating the radar in a specific radar mode;

b) recording antenna side-lobes signals received by the RF sensors, for each direction of the antenna beam in predefined steps; and

c) correlating readings of the RF sensors with the antenna's main beam direction.

5. The method according to claim 3, wherein at least one of the LUT is generated by: a) activating the radar;

b) recording antenna side-lobes signals received by the RF sensors, for each mode of operation of the radar occurring in a specified order; and

c) correlating readings of the RF sensors with the radar's modes of operation.

6. The method according to claim 1, the radar is installed upon a maneuverable platform and wherein the extrapolation of the spatial direction of the antenna takes into account the spatial velocity of the maneuverable platform.

7. A system for extracting operational features of a radio frequency (RF) radar or of an antenna thereof, usable for simulating virtual targets for the radar, the system comprising:

at least three RF sensors located proximal to the antenna configured to sample in real-time RF signals transmitted by the radar antenna and received by the a least three RF sensors;

one or more databases configured to store pre-generated calibration data that correlates pre-generated samples of RF signals with operational features of the radar or the antenna; and

a controller configured to extrapolate the operational features comprising at least one of: spatial direction of the antenna; and mode of operation of the radar respectively, based on the real-time sampled RF signals and the pre-generated calibration data.

8. The system according to claim 7, wherein the RF sensors are further configured to transmit RF signals and wherein the system is further configured to inject RF signals by the RF sensors into the antenna, wherein the injected signals mimic a radar echo from a specified virtual target.

9. The system according to claim 7, wherein the pre-generated calibration data is stored on one or more look up tables (LUT).

10. The system according to claim 9, wherein at least one of the LUT is generated by: d) activating the radar in a specific radar mode;

e) recording antenna side-lobes signals received by the RF sensors, for each direction of the antenna beam in predefined steps; and

f) correlating readings of the RF sensors with the antenna's main beam direction.

11. The system according to claim 9, wherein at least one of the LUT is generated by: d) activating the radar;

e) recording antenna side-lobes signals received by the RF sensors, for each mode of operation of the radar occurring in a specified order; and

f) correlating readings of the RF sensors with the radar's modes of operation.

12. The system according to claim 7, the radar is installed upon a maneuverable platform and wherein the extrapolation of the spatial direction of the antenna takes into account the spatial velocity of the maneuverable platform.

13. A computer program product for extracting operational features of a radio frequency (RF) radar or of an antenna thereof, usable for simulating virtual targets for the radar, the system comprising, the computer program product comprising:

a computer readable storage medium having computer readable program embodied therewith, the computer readable program comprising:

computer readable program configured to sample in real-time RF signals transmitted by the radar antenna and received by a least three RF sensors;

computer readable program configured to store pre-generated calibration data that correlates pre-generated samples of RF signals with operational features of the radar or the antenna; and

computer readable program configured to extrapolate the operational features comprising at least one of: spatial direction of the antenna; and mode of operation of the radar respectively, based on the real-time sampled RF signals and the pre-generated calibration data.

14. The computer program product according to claim 13, wherein the RF sensors are further configured to transmit RF signals and wherein the computer program product further comprises computer readable program configured to inject RF signals by the RF sensors into the antenna, wherein the injected signals mimic a radar echo from a specified virtual target.

15. The computer program product according to claim 13, wherein the pre-generated calibration data is stored on one or more look up tables (LUT).

16. The computer program product according to claim 15, wherein at least one of the LUT is generated by:

g) activating the radar in a specific radar mode;

h) recording antenna side-lobes signals received by the RF sensors, for each direction of the antenna beam in predefined steps; and

i) correlating readings of the RF sensors with the antenna's main beam direction.

17. The computer program product according to claim 15, wherein at least one of the LUT is generated by:

g) activating the radar;

h) recording antenna side-lobes signals received by the RF sensors, for each mode of operation of the radar occurring in a specified order; and

i) correlating readings of the RF sensors with the radar's modes of operation.

18. The computer program product according to claim 13, the radar is installed upon a maneuverable platform and wherein the extrapolation of the spatial direction of the antenna takes into account the spatial velocity of the maneuverable platform.