Jamming device and method for suppressing the detection of an object

Abstract

A jamming device (2) and a method for suppressing and identifying the detection of an object (4) by a detection unit (8) installed in a target are described. The jamming device (2) comprises a signal processor (6) configured to analyze the characteristics of a radar signal (R) emitted by the detection unit (8) and to generate a jamming signal (S) based on the analyzed characteristics, as well as a jamming signal unit (12) with at least one receiving antenna (10) for receiving a radar signal (R) emitted by the target and at least one transmitting antenna (14) for emitting the generated jamming signal (S). The jamming signal unit (12) is configured to detect the radar signal (R) emitted by the detection unit (8) during operation, and the signal processor (6) is further configured to activate and deactivate the jamming device (2) depending on the detected radar signal (R).Furthermore, the jamming signal unit (12) is configured to permanently detect the emitted radar signal (R) and to operate at least one transmitting antenna (14) simultaneously.

Description

[0001] The invention relates to a jamming device for suppressing the detection of an object and a method for suppressing the detection of an object.

[0002] Radar systems are commonly used to detect objects such as land, air, or water vehicles. Radar systems enable the highly accurate detection of vehicles over long distances of several hundred kilometers, thus determining their location and / or direction of movement. Radar systems are particularly useful in the military context for reconnaissance not only of friendly vehicles but also, and especially, of enemy vehicles.

[0003] US patent 6,993,877 B1 discloses a multi-antenna jamming system for aircraft. In this system, multiple antennas are used to minimize shadowing effects and to synchronize jamming signals with the aircraft's RF seeker.

[0004] US Patent 6 424 286 B1 discloses an in-seeker jamming device that uses existing antennas and amplifiers of an RF aircraft to disrupt active protection systems and render a target vulnerable.

[0005] For this reason, conversely, for defensive purposes it is necessary to reduce the signature of one's own vehicles / aircraft for enemy radar devices as much as possible or to jam the enemy radar devices so that enemy forces cannot detect or locate the vehicles / aircraft.

[0006] Such suppression of detection poses ever greater challenges for technology due to increasingly precise radar systems. For example, signature reductions of certain projectiles are insufficient to overcome an APS radar. Radar measurements have shown that even hunting ammunition can be reliably detected with a continuous-wave radar (FMCW radar) at a distance of several meters, for example, 20 to 60 meters from the target. In fact, only a transmission power of the FMCW radar equivalent to the radiated power of a standard mobile phone is required.

[0007] The invention is therefore based on the objective of providing a jamming device and a method by which the detection of an object is at least suppressed.

[0008] According to the invention, the problem with regard to the device is solved by the subject matter of claim 1. With regard to the method, the problem is solved by the subject matter of dependent claim 9.

[0009] Advantageous embodiments, further developments, and variants are the subject of the dependent claims. The advantages and preferred embodiments listed with regard to the device are to be applied analogously to the method and vice versa.

[0010] The jamming device serves to suppress detection and, in particular, the identification of an object by a detection unit installed in a target. For the purposes of this application, the term "detection unit" can be understood to mean an (enemy) radar device, and in particular a military air-to-air or surface-to-air radar, e.g., an APS radar. For the purposes of this application, the term "identification" can be understood to mean that real threats can be distinguished from "fake" threats. In the case of the latter, no countermeasures would be initiated, as otherwise the available countermeasures would be quickly exhausted.

[0011] The jamming device includes a signal processor configured to analyze the characteristics of a radar signal emitted by the detection unit. For the purposes of this application, the term "characteristics" can be understood to mean radar-typical characteristics, such as—but not limited to—the power or frequency of the emitted radar signal.

[0012] Furthermore, the signal processor is configured to generate a jamming signal based on the analyzed characteristics. This allows for the generation of a jamming signal that is adapted to the radar signal and therefore reliable, thus increasing the effectiveness of the jamming device.

[0013] Furthermore, the jamming device includes a jamming signal unit with at least one receiving antenna for receiving a radar signal emitted by the target and at least one transmitting antenna for emitting the generated jamming signal.

[0014] The jamming unit is configured to detect the radar signal emitted by the detection unit during operation, with the signal processor further configured to activate and deactivate the jamming device depending on the detected radar signal. The jamming unit is also configured to continuously detect the emitted radar radiation and to operate at least one transmitting antenna simultaneously.

[0015] The two features of the jamming unit described above, more precisely the underlying logic, ensure that the device is not activated as long as the (opposing) detection unit is not yet activated, thus preventing passive projectile tracking, e.g., via triangulation. Likewise, the jamming unit, and in particular at least one transmitting antenna, is deactivated as quickly as possible when no APS radar signal can be detected. The at least one receiving antenna does not need to be deactivated in this process.

[0016] Rather, the at least one receiving antenna of the jamming unit continuously detects electromagnetic radiation arriving at the jamming device (e.g., radar radiation or radiation in the optical wavelength range of UV, VIS, NIR, SWIR, MWIR, LWIR, FIR). According to the invention, this is intended to occur, with the best possible shielding of the receiving antenna from the transmitting antenna, even when the at least one transmitting antenna of the jamming unit is transmitting at full power. This then represents the so-called "best case".

[0017] The jamming device described above can, for example, be installed in a projectile or a military cruise missile to suppress its detection by an enemy interceptor.

[0018] According to one embodiment, the jamming unit includes a receiver, the receiver comprising at least one receiving antenna. Thus, the receiver is configured to detect the radar signal emitted by the detection unit during operation. Furthermore, the receiver may additionally include components such as a low-noise amplifier (LNA), a down converter, a mixer stage, filter stages, and an analog-to-digital converter (ADC).

[0019] It is also preferred that the jamming signal unit includes a transceiver, wherein the transceiver includes at least one transmitting antenna. Furthermore, the transceiver may include components such as a preamplifier (PA), upconverter, mixer stage, filter stages, and digital-to-analog converter.

[0020] According to the invention, the polarization direction of the at least one receiving antenna and the polarization direction of the at least one transmitting antenna are shifted relative to each other by 90°. This ensures the best possible suppression of coupling between the individual components. For example, it is possible to achieve a suppression of 30 dB. In addition to the 90° shift, time-division multiplexing can also be provided, in which short periods of reception are followed by longer periods of transmission with precisely this polarization direction, transmission frequency, pulse repetition frequency (PRF), etc.

[0021] In a further embodiment, the jamming device can also include an optical beam unit for countering optical detection by the detection unit, particularly in a close-range area. The close-range area can be between 50m and 100m, particularly between 30m and 70m, and especially between 40m and 60m, or even more than 200m in front of the target. The greater the distance, the more complex the required optical camera system becomes. If one wants to track an approaching threat using only a day-vision or thermal imaging camera, the required lens focal length increases linearly with the distance at which the threat is to be identified and tracked. The lens diameter also increases synchronously with the focal length, since (without active exposure) one must work with the smallest possible f-numbers (close to f / 1.0) to gather as much light or heat radiation as possible.Only in this way can reasonably high-contrast, low-noise images be achieved with short exposure times (to avoid motion blur). With R. Ident(Identification range or identification distance) = 250m. For example, thermal imaging optics may require a focal length of 400mm, and the outer diameter of these lenses is then even greater. The underlying principle for close-range applications is that focal lengths, and therefore lens apertures, increase with DRI (Detection, Recognition, Identification) distances. Therefore, optical detection systems are more likely to be found at close range. Projectile tracking at close range is thus possible purely passively (using triangulation). At greater distances, active illumination is used, and as a countermeasure, light can be reflected back to overstimulate (saturate) the systems. However, passive measurements can also be susceptible to interference from overstimulation and / or false signals (spoofing).

[0022] Alternatively, a modern detection unit in the form of an APS could, in principle, be equipped with active, pulsed light sources (similar functionality to that of radar).

[0023] Unlike radar, Doppler shifts used to measure projectile velocity cannot be evaluated in the optical range. Therefore, separation between the environment and flying objects (Moving Target Indication, MTI) is not directly achieved through measurement technology. However, it can be accomplished using a rapid subtraction technique between successive images (the background is subtracted down to noise). As a countermeasure, interference can also be introduced using light of the same wavelength (optical wavelengths and polarization filters are to be expected). This can lead to overexposure, render the received radiation unusable, and generate false targets (spoofing) through corresponding phase shifts. It is crucial to note, however, that the background varies from image to image, for example, when "tracking" a flying object.

[0024] In one embodiment, the generated jamming signal is coded, in particular using Code Division Multiple Access or Barker Code, to differentiate or subtract the remaining coupling and also the smart jammer / spoofer echo from the actual APS radar. Furthermore, the APS radar itself may be coded, or most likely is. For the jamming device, this means that it is significantly more difficult to jam the entire signal (across the entire frequency range) or to imitate a false target.

[0025] Furthermore, the latency (here: the time it takes for the analyzer to identify the new radar frequency, radar technology, optical wavelength, optical technology, etc.) after frequency hopping is minimized. Time multiplexing is planned as a backup solution.

[0026] As described above regarding the installation location of the jamming device, the object is designed in one embodiment as a military missile. In particular, the military missile can be, for example – but not limited to – a projectile, a rocket, or a cruise missile.

[0027] According to one embodiment, the at least one receiving antenna and / or the at least one transmitting antenna are arranged on the surface of the object or within the object. This achieves the best possible localization and the best possible operation of the antennas.

[0028] In a further embodiment, the at least one receiving antenna and / or the at least one transmitting antenna is / are configured as a broadband antenna. Specifically, the at least one receiving antenna and / or the at least one transmitting antenna is / are configured as a spiral antenna, a Vivaldi antenna, a horn antenna (particularly at higher frequencies), or a patch antenna. Such antennas have proven suitable for the essential purpose of the invention.

[0029] Specifically, the problem addressed in the method is solved by a method for suppressing the detection and, in particular, the identification of an object by a detection unit installed in a target. According to the invention, the method is carried out using a jamming device of the type described. The method comprises the following steps: - Capturing and analyzing the characteristics of a radar signal emitted by the target using at least one receiving antenna, a jamming unit, and a signal processor; - Generating a noise signal based on the analyzed properties; - Radiation of the interference signal by means of at least one transmitting antenna of the interference signal unit, the procedure further comprises the following steps: - Activating and deactivating the device depending on the detected radar signal; - permanent detection of the radar signal and simultaneous operation of at least one transmitting antenna.

[0030] Simultaneous operation of at least one transmitting antenna only occurs if possible.

[0031] In one embodiment, the method comprises the following step: - Encoding the generated interference signal, in particular using Code Division Multiple Access, Spoofing or Barker Code.

[0032] An embodiment of the invention is explained in more detail below with reference to the figure. This shows a highly simplified representation: Fig. 1 A sketched structure of the jamming device according to the invention, which is arranged in a military missile.

[0033] The jamming device 2 is arranged in an object 4 designed as a military missile. Specifically, the jamming device 2 is arranged in a warhead tip of the military missile.

[0034] The jamming device 2 comprises a signal processor 6. The signal processor 6 is configured to analyze the properties of a radar signal R emitted by a detection unit 8. For this analysis, the jamming device 2 receives the radar signal R via at least one receiving antenna 10 of a jamming signal unit 12. The jamming signal unit 12 is also part of the jamming device 2 and may include a receiver that has the at least one receiving antenna 10. Furthermore, the signal processor 6 is also configured to generate a jamming signal S based on the analyzed radar signal R. The generated jamming signal S is then emitted by at least one transmitting antenna 14.

[0035] In this case, the emitted interference signal S serves to suppress detection and especially to prevent the detection unit from identifying object 4, in order to at least make defensive measures against object 4 more difficult.

[0036] According to the invention, the jamming signal unit 12 is further configured to detect, firstly, the radar signal R emitted by the detection unit 8 during operation, wherein the signal processor 6 is further configured to activate and deactivate the jamming device 2 depending on the detected radar signal R. Secondly, the jamming signal unit 12 is configured to continuously detect the radar signal R emitted by the detection unit 8 even when the at least one transmitting antenna 14 is transmitting at full power.

[0037] To defend against or suppress optical detection of the object 4, the jamming device 2 further comprises an optical beam unit 16.

[0038] The invention is not limited to the embodiment described above. Rather, other variants of the invention can also be derived by a person skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the embodiment can also be combined with one another in other ways without departing from the subject matter of the invention. Reference symbol list 2. Interference device 4 objects 6 Signal processor 8 detection units 10 Receiving antenna 12 Interference signal unit 14 transmitting antenna 16 optical beam units R Radar signal of the detection unit S Interference signal

Claims

[1] Jamming device (2) for suppressing the detection and identification of an object (4) by a detection unit (8) installed in a target, the jamming device (2) comprising: - a signal processor (6) configured to analyze properties of a radar signal (R) emitted by the detection unit (8) and to generate an interference signal (S) based on the analyzed properties; - an interference signal unit (12) with at least one receiving antenna (10) for receiving a radar signal (R) emitted by the target and at least one transmitting antenna (14) for emitting the generated interference signal (S), wherein - the jamming signal unit (12) is configured to detect the radar signal (R) emitted by the detection unit (8) during operation, wherein the signal processor (6) is further configured to activate and deactivate the jamming device (2) depending on the detected radar signal (R); and - the interference signal unit (12) is further configured to permanently detect the emitted radar signal (R) and to operate the at least one transmitting antenna (14) simultaneously therewith, and wherein - the polarization direction of the at least one receiving antenna (10) and the polarization direction of the at least one transmitting antenna (14) are shifted by 90° to each other. [2] Jamming device according to claim 1, wherein the jamming signal unit (12) comprises a receiver, wherein the receiver comprises the at least one receiving antenna (10). [3] Jamming device according to claim 1 or 2, wherein the jamming signal unit (12) comprises a transceiver, the transceiver comprising the at least one transmitting antenna (14). [4] Jamming device (2) according to one of the preceding claims, which further comprises an optical beam unit (16) for warding off optical detection by the detection unit (8), in particular in a close range. [5] Jamming device (2) according to one of the preceding claims, wherein the generated jamming signal (S) is coded, in particular coded by means of Code Division Multiple Access or Barker Code. [6] Jamming device (2) according to one of the preceding claims, wherein the object (4) is designed as a military missile. [7] Jamming device (2) according to one of the preceding claims, wherein the at least one receiving antenna (10) and / or the at least one transmitting antenna (14) is / are arranged on the surface of the object (4) or within the object (4). [8] Jamming device (2) according to one of the preceding claims, wherein the at least one receiving antenna (10) and / or the at least one transmitting antenna (14) is / are designed as a broadband antenna. [9] Jamming device (2) according to one of the preceding claims, wherein the at least one receiving antenna (10) and / or the at least one transmitting antenna (14) is / are designed as a spiral antenna or a Vivaldi antenna or a patch antenna or a horn antenna. [10] Method for suppressing the detection of an object (4) by a detection unit (8) installed in a target, the method being carried out by means of a jamming device according to one of claims 1 to 9, the method comprising the following steps: - detecting and analyzing properties of a radar signal (R) emitted by the target by means of at least one receiving antenna (10), an interference signal unit (12) and a signal processor (6); - generating a disturbance signal (S) based on the analyzed properties; - emitting the interference signal (S) by means of at least one transmitting antenna (14) of the interference signal unit (12), the method further comprising the steps of: - activating and deactivating the jamming device depending on the detected radar signal (R); - permanent detection of the radar signal (R) and simultaneous operation of at least one transmitting antenna (14). [11] The method of claim 10, further comprising the step of: - Coding the generated interference signal (S), in particular by means of Code Division Multiple Access, spoofing or Barker Code.

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