EP0512202B1 - Method for protecting an IR-radiation emitting object and projectile for putting this method in practice - Google Patents

Description

The invention relates to a method for protecting objects emitting IR radiation according to the preamble of claim 1 and to a projectile for carrying out this method.

It is known to protect an object emitting IR radiation, in particular ships, but also aircraft and tanks, against missiles equipped with IR seekers in that one or - in succession - several objects are detected adjacent to the object when a missile is approached by means of a missile in the airspace pyrotechnic dummy target clouds are erected, which deflect the IR seeker head of the missile from the object and towards it. For example, reference is made to EP 0 240 819 A2, which describes a method of the generic type and in which throwing bodies producing dummy targets are placed and fired at predetermined times in predetermined spatial areas, in such a way that the dummy targets generated are at predetermined intervals in time and space on a Deflection curve and should be controlled by the missile so that its trajectory merges into the deflection curve and finally in the deflection direction.

The apparent target clouds consist of burning phosphor flares, that is, platelets or strips coated with red phosphorus, which are ejected from the throwing body at the desired location and ignited in the process.

However, the latest development in IR seekers is now to make the seekers "intelligent" and thus immune to conventional IR dummy targets, ie to design them in such a way that they respond to the object signature, in particular the ship's signature. The development is being driven in different directions. For example, an adaptive "tracking gate" is used in the imaging "gated video target search heads", which can be adapted exactly to the size of the ship to be hit by means of a video processor and suitable algorithms. The viewing window of the seeker head can thus be reduced to the size of the ship after being switched on, with the result that apparent target clouds which are generated outside this adaptive window, that is to say above or next to the ship, remain ineffective. With "correlation trackers", the target is usually activated by a human operator. After switching to the object, the search head finds its way to the target unhindered by comparing (cross-correlation) two successive images (stored reference image / current image), even if IR apparent target clouds are generated in the vicinity of the object. Another method for false target elimination consists in a frequency analysis by the seeker head, which can distinguish between the radiation characteristic of the IR emitter of the target having a comparatively low temperature (for example ship engines) and the radiation characteristic of a hot false target cloud. To summarize, it can be said that the known IR-shining target clouds are not able to To protect an object against missiles equipped with intelligent search heads, the object of the present invention is therefore to provide a method and projectile with which it is possible to deflect missiles equipped with intelligent search heads from the target.

According to the invention, this object is achieved procedurally by the features of patent claim 1 and device-wise by the features of patent claim 9.

Particular embodiments of the method and the device or the throwing body according to the invention are the subject of the corresponding subclaims.

The invention is therefore based on the basic idea that a deflection of intelligent search heads is only possible if the reception of the ship's signature for the search head is considerably disturbed first, i.e. - seen from the search head - the ship's signature is permanently destroyed, i.e. the search head is a must make new goals. It is only at this point in time that it is possible to deflect using known IR target clouds that are attractive to the seeker head, that is, to have the seeker head connected to the dummy target clouds, provided, of course, that the actual target is "covered" in this way that the seeker head does not switch back to the actual target.

Fig. 1

eine grafische Darstellung zur Erläuterung der Unwirksamkeit üblicher IR-Scheinzielwolken gegenüber einen Suchkopf mit adaptivem "tracking gate",

Fig. 2

eine grafische Darstellung ähnlich derjenigen von Fig. 1, zur Erläuterung der Wirksamkeit des Erfindungsverfahrens auch bei einem Suchkopf mit adaptivem"tracking gate",

Fig. 3

eine Grafik des Strahlstärkeverlaufs bei einer Störstrahlungswolke nach der Erfindung, und

Fig. 4

eine Schemaskizze der Ablenkung eines anfliegenden Flugkörpers mit intelligentem Suchkopf.

The invention is explained below with reference to the drawing. Show on the drawing:

Fig. 1

2 shows a graphical representation to explain the ineffectiveness of conventional IR dummy target clouds compared to a seeker head with adaptive "tracking gate",

Fig. 2

2 shows a graphic representation similar to that of FIG. 1, to explain the effectiveness of the inventive method even with a seeker head with adaptive "tracking gate",

Fig. 3

a graph of the radiant intensity curve for an interference radiation cloud according to the invention, and

Fig. 4

a schematic sketch of the deflection of an approaching missile with an intelligent seeker head.

1 shows the field of view A of an imaging IR seeker head. In this field of view A is the ship to be attacked. After the search head is switched to the target (ship), the search field is reduced to a window B roughly corresponding to the size of the ship, with automatic adjustment regardless of the distance between the search head and ship. If, as is customary up to now, lateral fictitious target clouds are set from the ship, as shown in the figure, then these obviously remain ineffective because they are located outside the window B. If, however, the dummy target clouds were set up within window B, i.e. at a point between the ship and the approaching missile, the missile would not be deflected from the ship, i.e. the missile would maintain its - intended - trajectory.

In contrast to this, the procedure according to the invention is such that large interference clouds, preferably successively "migrating" to the outside, are generated between the ship and the approaching missile, which initially disturb the reception of the ship's signature and thus cause the seeker head to be lost (FIG. 2) . The seeker head switches to the outward focus of radiation; a renewed "recognition of the ship's signature" is prevented by the persistent camouflage effect of the interference radiation cloud. By using conventional IR dummy target clouds D, the seeker head can now be gradually deflected from the ship. How this deflection process works in detail will be explained below.

The radiation course of the interference radiation cloud should be as shown in FIG. 3. More precisely, the radiance should rise very quickly to a high value in order to obtain the most possible delay-free effect, namely in that disturbances in the ship's signature are caused in the IR seeker head, which result in a loss of target. Likewise, the drop in the beam strength to a comparatively low value should take place very quickly in order to avoid a continued attraction of the seeker head. The phase of strong radiation should last for a maximum of two to four seconds. This phase of high radiation intensity is then followed by a phase of comparatively low radiation intensity, for which a period of at least 15 seconds must be set. This phase of low beam intensity serves to ensure a permanent modification of the ship's signature. The modification is caused by temporally and spatially varying damping and radiation effects of the active substance.

The radiation intensity curve mentioned can be achieved by throwing bodies, the effective mass of which is a mixture of the following components: small-area phosphor flares: about 50% large phosphor flares: about 10% Phosphorus granules: about 40%

Optimization can be based on radiometer measurements for the relevant wavelength ranges.

The process of deflecting an approaching missile will now be explained with reference to FIG. 4. In FIG. 4, 10 denotes the ship to be protected, 11 the missile flying towards the ship, which is equipped with an intelligent IR seeker head 11a. 12 indicates the flight path of the missile 11, and the dashed lines 13 correspond to the limitation of the viewing window of the seeker head 11a, which is already connected to the ship 10, that is to say the window B, for example of FIG. 1. As soon as the approach of the missile 11 has been determined by the ship 10, its distance from the ship and its speed are determined. Depending on these values, three throwing bodies are now fired from the ship at short time intervals, for example at a distance of one second, which then generate interference radiation clouds at points 1, 2 and 3 of FIG. 4, i.e. at points between Ship 10 and missile 11 lie next to each other and essentially cover the area between the boundaries 13. The throwing bodies release their active mass at about the height of the ship, i.e. at a height of 30 meters, by igniting the active mass. The three interference radiation clouds 1, 2, 3 induce interference signals in the electronic seeker head components, such as the "target reference detector", the "gate generator" and / or the correlation computer, which lead to the destruction of the ship's signature, in the aforementioned first radiation phase in other words, a loss of the seeker target.

Immediately after the last interference radiation cloud has been created, the first apparent target cloud 4 is deployed, specifically in the edge region of the viewing windows of the search head 11a delimited by the dashed lines 13. The apparent target cloud 4, which is also produced in a conventional manner by a missile launched by the ship 10, should have a large area and a high radiation intensity in all relevant wavelength ranges.

Additional shining target clouds 5, 6, 7, 8 and 9, each created at intervals of 4 seconds, for example, form a radiating, horizontal, ship-like "tube" in the projection of the seeker head, the center of radiation of which is continuously outward (from 4 to 9) wanders.

The seeker head 11a will follow the radiation center of gravity of the apparent target clouds moving outwards, since these represent a much more attractive target than the ship 10 in terms of beam strength and area, especially since its IR signature is "blurred" or persistently "camouflaged" by the interference radiation clouds 1, 2, 3 can no longer be differentiated from the radiation from the background.

The approaching missile 11 is thus deflected ever further from the ship 10.

As already mentioned, the apparent target clouds 4 to 9 are created using conventional active materials, which generally consist of phosphor flares. The height of the flare decomposition should be at the top of window B, i.e. at ship height. If one assumes a height of 30 meters and a sinking speed of 2.5 m / s, the flare action time is 12 seconds. Such a duration of action in conjunction with the above-mentioned generation sequence of 4 seconds of clouds 4 to 9, the large-scale dimension of the clouds and the preference for a radiation frequency adapted to the ship's radiation leads to an optimal deflection of the seeker head and thus of the missile.

As can be seen from FIG. 4, the interference radiation clouds 1 to 3 and the apparent target clouds 4 to 9 lie essentially on a pitch circle around a center point, which is located on the ship 10. This has the advantage that all of the throwing bodies producing clouds 1 to 9 can be fired in succession from a single launching platform, it being only necessary to gradually pivot the platform. It is usually not necessary to adjust the height of the platform during this pivoting movement, unless the ship 10 is guiding during the process the shots are caused by strong movements (swell). Another great advantage of the creation of the apparent target clouds 4 to 9 on a pitch circle is that from the perspective of the missile, a coherent "apparent target band" is created, with the formation of a radiation center at the point furthest away from the ship.

With the help of the circular application process, a faster deployment of the throwing bodies, each optimally adapted to the threat direction, is guaranteed, with a deflection direction always perpendicular to the threat direction.

It is not necessary that all of the dummy target clouds are 4 to 9 IR dummy targets, rather a combination of IR dummy target clouds, i.e. clouds made of phosphor flares, and RF clouds, i.e. clouds made of dowels, is advisable in order to appropriately interfere with search heads with radar control or to be able to distract.

Of course, the invention is not limited to the exemplary embodiment shown, rather numerous modifications are possible without leaving the scope of the invention. This applies to the number of interference and false target clouds to be created, their temporal and spatial distances, the composition of their active masses, the caliber of the projectiles and the number and movement of the launch tubes (thrower). In addition, there are many options for controlling the thrower on the basis of pre-programmed or threat-dependent computer systems. In any case, it must be ensured that the ship's signature is destroyed first, because it is only then possible to initiate a deflection process.

Claims (10)

1. A method of protecting IR-radiating targets (10), more particularly ships, from missiles (11) having smart, more particularly scanning, imaging correlating and/or spectrally filtering IR search heads (11a), the missile (11) being located from the target (10) to be protected and the missile speed, flight direction and instantaneous distance from the target (10) being determined, characterised in that at least one large-area and homogeneous pyrotechnical interference radiation cloud (1, 2, 3) is produced from the target (10) for protection closely adjacent the same and between it and the missile (11), such cloud first emits a brief and intensive IR radiation which inhibits reception of the characteristic IR signature of the target (10) by the search head (11a) and disturbs its latch-on and pursuit electronics, and then for a comparatively long time emits a weak transmission-reducing IR radiation substantially in simulation of background radiation, and in that starting immediately after termination of the intense radiation phase of the interference radiation cloud (1 - 3) but at least during the weak radiation phase thereof a number of large-area and homogeneous pyrotechnical infrared dummy target clouds (4 - 9) substantially resembling the IR signature of the target (10) are fired therefrom consecutively, the dummy target clouds (4 - 9) being so cohesively adjacent one another starting from a place adjacent the interference radiation cloud (1 - 3) as to guide the search (11a) and therefore the missile (11) stepwise away from the target (10) in a substantially transverse direction to the missile approach direction.
2. A method according to claim 1, characterised in that a number of large-area interference radiation clouds (1 - 3) are produced adjacent one another at short intervals of time between the target (10) for protection and the missile (11).
3. A method according to claim 2, characterised in that the time intervals are of the order of magnitude of one second.
4. A method according to any of claims 1 to 3, characterised in that the dummy target clouds (4 - 9) are produced at intervals of two to ten seconds, preferably four seconds.
5. A method according to any of claims 1 to 4, characterised in that the intense IR radiation phase of the interference radiation cloud (1, 2, 3) lasts approximately two seconds and the subsequent weak radiation and transmission reduction phase lasts at least 10 seconds.
6. A method according to any of claims 1 to 5, characterised in that radar dummy target clouds are produced in addition to the IR location dummy target clouds (4 - 9).
7. A method according to any of claims 1 to 6, characterised in that at least the dummy target clouds (4 - 9) are produced on a partial circle whose centre is on the target (10) for protection.
8. A method according to claim 7, characterised in the dummy target cloud partial circle is substantially a quadrant.
9. A projectile for producing the interference radiation cloud (1 - 3) in the method according to any of the previous claims, characterised in that the active composition of the projectile is a mixture of approximately 10% of large-area phosphorus flares, approximately 50% of small-area phosphorus flares and the mixture of approximately 40% phosphorus granulate, the intense IR radiation phase of the interference radiation cloud (1, 2, 3) produced by the projectile lasting about two seconds.
10. A projectile for the practice of the method according to any of claims 1 to 8 or claim 9, characterised by identical calibre for the production of interference radiation clouds (1 - 3) and for the production of dummy target clouds (4 - 9).

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