DE102023127787B3 - Jamming device and method for suppressing the detection of an object - Google Patents

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 specified. The jamming device (2) has a signal processor (6) which is set up 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, and 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). The interference signal unit (12) is set up to detect the radar signal (R) emitted by the detection unit (8) during operation, the signal processor (6) further being set up to activate and deactivate the jamming device (2) depending on the detected radar signal (R). Furthermore, the interference signal unit (12) is designed to permanently detect the emitted radar signal (R) and to operate the at least one transmitting antenna (14) simultaneously therewith.

Description

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

Radar devices are usually used to detect objects such as land, air or water vehicles. Radar devices make it possible to detect vehicles with great accuracy over long distances of several hundred kilometers and thus to indicate their location and/or direction of movement. Radar devices are particularly useful in the military sector to detect not only one's own vehicles, but especially enemy vehicles.

Out of US 6 993 877 B1 is a multi-antenna jamming system for aircraft. Several antennas are used to minimize shadowing effects and to synchronize jamming signals with the aircraft's RF seeker.

Out of US 6 424 286 B1 is an in-seeker jammer that uses existing antennas and amplifiers of an RF aircraft to disrupt active protection systems and render a target vulnerable.

For this reason, 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.

Such suppression of detection presents technology with ever greater challenges due to increasingly precise radar devices. For example, signature reductions of certain projectiles are not sufficient 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 20m to 60m, from the target. In fact, the FMCW radar only needs a transmission power that corresponds to the radiation power of a standard mobile phone.

The invention is therefore based on the object of specifying a jamming device and a method by means of which the detection of an object is at least suppressed.

According to the invention, the object is achieved with regard to the device by the subject matter of claim 1. With regard to the method, the object is achieved by the subject matter of the independent claim 9.

Advantageous embodiments, further developments and variants are the subject of the subclaims. The advantages and preferred embodiments listed with regard to the device are to be transferred analogously to the method and vice versa.

The jamming device serves to suppress the detection and in particular the identification of an object by a detection unit installed in a target. The term "detection unit" in the sense of this application can be understood as an (enemy) radar device and in particular a military air-to-air or ground-to-air radar, e.g. an APS radar. The term "identification" in the sense of this application can be understood as the ability to distinguish between real threats and "fake" threats. In the case of the latter, no countermeasures would be triggered, as otherwise the available countermeasures would quickly be used up.

The jamming device has a signal processor that is set up to analyze properties of a radar signal emitted by the detection unit. The term "properties" in the context of this application can be understood as radar-typical properties, such as - but not limited to - the power or frequency of the emitted radar signal.

Furthermore, the signal processor is designed to generate an interference signal based on the analyzed properties. This allows an interference signal to be generated that is adapted to the radar signal and is therefore reliable, which increases the effect of the interference device.

Furthermore, the jamming device has 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.

The interference signal unit is designed to detect the radar signal emitted by the detection unit during operation, with the signal processor also being designed to activate and deactivate the interference device depending on the detected radar signal. The interference signal unit is also designed to permanently detect the emitted radar radiation and to operate the at least one transmitting antenna simultaneously.

The two features of the jamming signal unit described above, or more precisely the stored logic, ensure that the device is not activated as long as the (enemy) detection unit is not activated, in order to avoid passive projectile tracking, e.g. by means of triangulation. The jamming signal unit and in particular the at least one transmitting antenna are also switched off as quickly as possible when no more APS radar signal can be detected. The at least one receiving antenna does not have to be switched off in this case.

Rather, the at least one receiving antenna of the interference signal unit constantly measures electromagnetic radiation arriving at the interference device (e.g. radar radiation or radiation in the optical wave range of UV, VIS, NIR, SWIR, MWIR, LWIR, FIR). According to the invention, this should also take place when the at least one transmitting antenna of the interference signal unit is transmitting at full power, provided that the receiving antenna is shielded as best as possible from the transmitting antenna. This then represents the so-called "best case".

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

According to one embodiment, the interference signal unit has a receiver, wherein the receiver has at least one receiving antenna. The receiver is thus set up to detect the radar signal emitted by the detection unit during operation. Furthermore, the receiver can additionally have components such as a low noise amplifier (LNA), down converter, mixer stage, filter stages and analog digital converter (ADC).

It may also be preferred if the interference signal unit has a transceiver, wherein the transceiver has at least one transmitting antenna. Furthermore, the transceiver may also have components such as a pre-amplifier (PA), up converter, mixer stage, filter stages and digital analog converter.

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 by 90° relative to one another. This ensures the best possible suppression of the coupling between the individual components. For example, it is possible to achieve a suppression with a value of 30 dB. In addition to the shift by 90°, time multiplexing can also be provided, in which reception takes place over short periods of time and then transmission takes place over longer ranges with exactly this polarization direction, transmission frequency, pulse repetition frequency PRF, etc.

In a further embodiment, the jamming device can also have an optical beam unit to prevent optical detection by the detection unit, in particular in a close range. The close range can have a value in the range between 50m and 100m, in particular between 30m and 70m and especially in the range between 40m and 60m or even more than 200m from the target. The greater the distance, the more complex the required optical camera system becomes. If you want to track an approaching threat with the day vision or thermal imaging camera alone, then the required lens focal length increases linearly with the distance at which you want to identify and track the threat. The lens diameter also increases synchronously with the focal length because (without active exposure) you have to work with the smallest possible aperture number (close to 1.0) in order to be able to collect a lot of light or thermal radiation. This is the only way to achieve reasonably high-contrast, low-noise images with short exposure times (to avoid motion blur). For R _Ident (identification range or identification distance) = 250m, thermal imaging optics may well require a focal length of 400mm, for example, and the outer diameter of these lenses is even higher. The particular application in the close range is based on the idea that focal lengths and thus also lens apertures increase with DRI (detection, recognition, identification) distances. Optical systems for detection are therefore more likely to be used in the close range. Projectile tracking is therefore possible in the close range purely passively (by means of triangulation). Active illumination is therefore used at greater distances, although as a countermeasure "back-beaming" can also be used to overdrive (saturate) the systems. Furthermore, particularly with passive measurements, interference from overdrive and/or false signals (spoofing) can occur.

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

A Doppler shift for measuring the projectile speed cannot be evaluated in the optical range, unlike in the radar range. A separation between the environment and flying objects (Moving Target Indication, MTI) is therefore not directly provided by the measuring technology. However, it can be achieved by a quick subtraction technique between images that follow one another in time (background subtracts itself down to the noise). As a countermeasure, interference can also be achieved with light of the same wavelength (optical wavelengths and polarization filters are to be expected), which can result in overloading, non-evaluability of the received radiation and false targets (spoofing) generated by corresponding phase shifts. However, it should be fundamentally noted that the background differs from image to image, for example if you "go along" with a flying object.

In one embodiment, the generated interference signal is coded, in particular using Code Division Multiple Access or Barker Code, in order to be able to differentiate or subtract the remaining coupling and also the own smart jammer / spoofer echo from the real APS radar. Furthermore, the APS radar can be coded or is most likely coded. For the jamming device, this means that it is significantly more difficult to interfere with the entire signal (across the entire frequency range) or to imitate a false target.

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

As already described above with regard to the installation location of the jamming device, the object is designed as a military missile in one embodiment. In particular, the military missile can be, for example - but not limited to - a projectile, a rocket or a cruise missile.

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 positioning and the best possible operation of the antennas.

In a further embodiment, the at least one receiving antenna and/or the at least one transmitting antenna is/are designed as a broadband antenna. In particular, the at least one receiving antenna and/or the at least one transmitting antenna is/are designed as a spiral antenna or a Vivaldi antenna or a horn antenna (particularly at higher frequencies) or a patch antenna. Such antennas have proven to be suitable for the purpose essential to the invention.

Specifically, the object directed to the method is achieved 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 by means of a jamming device of the type described. The method has the following steps:

• - detecting and analyzing properties of a radar signal emitted by the target by means of at least one receiving antenna of a jamming signal unit and a signal processor;
• - Generating a disturbance signal based on the analyzed properties;
• - emitting the interference signal by means of at least one transmitting antenna of the interference signal unit,
• the method further comprising the steps of:
• - Activation and deactivation of the device depending on the radar signal detected;
• - permanent detection of the radar signal and simultaneous operation of at least one transmitting antenna.

The simultaneous operation of at least one transmitting antenna only occurs if possible.

• - Kodieren des erzeugten Störsignals, insbesondere mittels Code Division Multiple Access, Spoofing oder Barker Code.

In one embodiment, the method comprises the following step:

• - Coding the generated interference signal, in particular by means of Code Division Multiple Access, spoofing or Barker Code.

• 1 ein skizzierter Aufbau der erfindungsgemäßen Störvorrichtung, die in einem militärischen Flugkörper angeordnet ist.

An embodiment of the invention is explained in more detail below using the figure. This shows in a highly simplified representation:

• 1 a sketched structure of the jamming device according to the invention, which is arranged in a military missile.

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.

The jamming device 2 has a signal processor 6. The signal processor 6 is designed to analyze properties of a radar signal R emitted by a detection unit 8. For analysis, the jamming device 2 receives the radar signal R via at least one receiving antenna 10 of an interference signal unit 12. The interference signal unit 12 is also part of the interference device 2 and can have a receiver which has the at least one receiving antenna 10. Furthermore, the signal processor 6 is further configured to generate an interference signal S based on the analyzed radar signal R. The generated interference signal S is then emitted by at least one transmitting antenna 14.

Here, the emitted interference signal S serves to suppress the detection and in particular also to identify the object 4 by the detection unit in order to at least make defensive measures against the object 4 more difficult.

According to the invention, the interference signal unit 12 is further 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 interference device 2 depending on the detected radar signal R. On the other hand, the interference signal unit 12 is configured to permanently 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.

To prevent or suppress optical detection of the object 4, the jamming device 2 further comprises an optical beam unit 16.

The invention is not limited to the embodiment described above. Rather, other variants of the invention can also be derived from this by the person skilled in the art without departing from the subject matter of the invention. In particular, all of the 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.

list of reference symbols

2

jamming device

4

object

6

signal processor

8

detection unit

10

receiving antenna

12

interference signal unit

14

transmitting antenna

16

optical beam unit

R

radar signal of the detection unit

S

interference signal

Claims (11)

Jamming device (2) for suppressing the detection and identification of an object (4) by a detection unit (8) installed in a target, wherein the jamming device (2) has: - a signal processor (6) which is set up 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 interference signal unit (12) is set up to detect the radar signal (R) emitted by the detection unit (8) during operation, wherein the signal processor (6) is further set up 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° relative to one another. jamming device according to claim 1 , wherein the interference signal unit (12) has a receiver, wherein the receiver has the at least one receiving antenna (10). jamming device according to claim 1 or 2 , wherein the interference signal unit (12) has a transceiver, wherein the transceiver has the at least one transmitting antenna (14). 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. Jamming device (2) according to one of the preceding claims, wherein the generated jamming signal (S) is coded, in particular by means of Code Division Multiple Access or Barker Code. Jamming device (2) according to one of the preceding claims, wherein the object (4) is designed as a military missile. Jamming device (2) according to one of the preceding claims, wherein the at least one receiving antenna (10) and/or the at least a transmitting antenna (14) is/are arranged on the surface of the object (4) or within the object (4). 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. 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. 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 the Claims 1 until 9 is carried out, 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) of an interference signal unit (12) and a signal processor (6); - generating an interference 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: - activating and deactivating the interference device depending on the detected radar signal (R); - permanently detecting the radar signal (R) and simultaneously operating the at least one transmitting antenna (14). procedure according to claim 10 , further comprising the step: - coding the generated interference signal (S), in particular by means of Code Division Multiple Access, spoofing or Barker Code.

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