GB2354312A

GB2354312A - Defence against terminally guided ammunition

Info

Publication number: GB2354312A
Application number: GB9702469A
Authority: GB
Inventors: Hans Moser; Werner Hasse
Original assignee: Rheinmetall Industrie AG; Rheinmetall W&M GmbH
Current assignee: Rheinmetall Industrie AG; Rheinmetall W&M GmbH
Priority date: 1996-02-09
Filing date: 1997-02-06
Publication date: 2001-03-21
Anticipated expiration: 2017-02-06
Also published as: DE19604745C1; FR2781043A1; FR2781043B1; GB9700308D0; GB9702469D0; GB2354312B

Abstract

A target (25) is protected against ammunition such as a projectile (23) guided in the terminal target approach phase by the detection of maximum reflected laser energy (24) from the target illuminated by laser (20). A decoy laser (1) is used adjacent the target (25) which generates a laser beam (24') identical in pulse train and wave length with a laser beam (21) emitted by a laser target illuminator (20) but at a higher energy level. The ammunition (23) is thus caused to assume a flight path which misses the intended target (25).

Description

2354312 TITLE Defence Against Terminally Guided Ammunition This invention

relates to a method and apparatus for defending installations against terminal phase guided ammunition by use of a deception process.

Methods are known for attenuating reflection characteristics using camouflage paint on targets.

DE 43 27 976 C 1, for example, describes a flare composition for the production of a false target. In this case a target-seeking projectile sensitive to radiation is deflected, from the target to be protected, by means of a prepared false target coated with the flare composition. This method, however, suffers not only from lack of flexibility, that is every target has a false associated target, but also from the further drawback that when camouflage paint is used the reflect ivity, particularly in the case of wet surfaces, is high.

Collapsible camouflage systems are also known, such as described in DE 41 19 030 Al. These are based on a fixed installation which cannot be relocated without the considerable expense of dismantling and reconstruction.

A further method for attenuating the reflection characteristics by fog production is described in DE 33 26 884 C2. In this system the target is screened by a smoke or fog, According to this invention there is also provided According to this invention there is also provided thus the emission of infrared radiation is prevented, so that the said object becomes invisible to a sensor. The drawback is that the fog-producing means is often activated too late to have a sufficient effect and moreover the number of fog-producing units that can be accommodated in a vehicle is limited. Such systems are also seriously affected, in operation, by the prevailing environmental conditions, in addition to which they may signal their own io position.

One object of this invention is to provide a method and apparatus by which a target under fire from ammunition guided in the terminal phase can be camouflaged in a more simple and efficient manner.

1.5 According to this invention there is provided a method for the deception of terminally guided ammunition controlled using a laser beam which marks a target from which radiation is reflected or dispersed, in which method a decoy apparatus adjacent the target is activated after the target has been acquired by the beam of a laser target illuminator, said decoy generating a laser beam of higher energy and with the same pulse repetition rate and wave length as the laser beam reflected from the target, which is transmitted direct to the ammunition whereby the said ammunition is guided by a spatial displacement of the decoy along a flight path away from the illuminated target.

According to this invention there is also provided According to this invention there is also provided apparatus wherein a decoy device comprising a detector unit associated with the target is connected to an evaluation and control unit and the output thereof is connected by a cable with a laser having a radiator positioned above or to the side of the target, the radiator being coupled by an optical fibre and an optical coupling unit to the decoy laser.

Using such a solution the target requires no additional consumable products such as fog-producing agents and there is comparative immunity from environmental influences as well as being undetectable through the inherent passivity. Furthermore, camouflaging can be effected rapidly.

The distance between the radiating unit and the decoy provides protection for the latter.

The method according to this invention also enables the laser target illuminator to be located and effectively combated.

The deception process is explained in more detail by reference to an example which is illustrated in the drawings.

In the drawings:

Figure 1 shows a fixed installation for a decoy, Figure 2 shows a further version of a decoy on a moving target, Figure 3 shows a general arrangement for the decoy, 4 and Figure 4 shows a block schematic diagram of the decoy.

As shown in Figure 1, a target 25 is marked in a known manner by a laser target illuminator (LZB), by which the selected target 25 is illuminated using an integrated laser. The marking is detected, by the scattered laser radiation, in an ammunition unit 23 which is guided in the terminal final approach phase. The ammunition has been fired by an jo artillery unit 22. The detection is effected by sensors (not illustrated) which are provided on the ammunition unit 23 and which receive the reflected laser radiation 24 from the target 25. The ammunition 23 guided in the final phase is directed towards the illuminated target 25 by an automatic flight path control system in a known manner using the reflected laser energy 24. Ammunition 23 guided in the final phase, such as that described in DE 29 18 858, is aligned by a target seeking head mounted in front of a detector affixed to the ammunition 23. In this process the detector determines the spatial -?0 direction of the received laser beam 24 as well as the angle between the laser beam 24 and the flight path angle of the ammunition 23. In this process the target seeking head, with the detector, detects the range, determined by the reflection from the target 25 of about 2f] (solid angle), according to. the maximum laser energy 24.

Using this system by which the ammunition 23 guided in the final phase functions, a decoy 1 which is spatially offset is associated with the target 25 with a radiation of preferably > 1 sr (interference radian), for example being a f ixed system o.5 within a convoy of combat vehicles. When appreciable laser radiation 21 is received from the laser target illuminator 20 the decoy 1 is automatically disconnected after the evaluation of the signals received. For this purpose it is necessary for the decoy 1 to be equipped with a deception laser 5, which is jo normally on stand-by but which may, in the space of only a second or so, generate a laser beam 24' pulsating in accordance with the laser signal 21 received. The radiated laser energy 24 of the decoy 1 is in this case appreciably greater than the laser energy 24 reflected from the target 25.

Using the operation characteristics of the ammunition 23 which is being guided in the final phase and the fact that evaluation by means of the detector on the ammunition 23 only tests for and seeks the maximum energy level of the scattered laser radiation 24, the ammunition 23 changes over, after a certain synchronisation time of the decoy 1, to lock onto the laser beam 24'of the decoy 1. The synchronisation time between the laser beam 24 and the laser beam 24' pulsed by decoy 1 is preferably only displaced by one pulse. The visual range of the detector of the ammunition 23 is defined by a conventional target seeking head not shown in the drawing and is great 6 enough to ensure that the spatial offset between the laser marking of the target 25 and the decoy 1 over the distance to the ammunition 23 will be negligible and thus still within the detector field (angle of aperture 15-600), in practice 15-2511, of o5 the ammunition 23. The ammunition 23 switches to the laser beam 24pulsed by the decoy 1 instead of to the reflected laser beam 24 and now moves towards the spatially offset radiation 9 of the decoy 1, as a result of which the actual target 25 is missed by a number of meters. The impact and detonation of io the ammunition 23 thus takes place in a non-critical zone.

As the radiation 9 from the decoy 1 transmits at a different angle in relation to the ammunition 23 as compared with the reflected laser beam 24, then the flight path of the ammunition 23 towards the target 25 is always changed. The greater the distance between the ammunition 23 and the target 25, the further away from the target 25 will the ammunition 23 be guided. The local spatial offset of the radiator 9 of the decoy 1 In relation to the target 25, in order to ensure effective deception, should not be allowed to exceed a radius of 100 m.

With a velocity of 300 m/s and a residual flight time of 15 s, the distance of the target 25 will be 4.5 km, whereas if only 8 s remain the distance is 2.4km. This means that if the distance of ammunition 23 from the target 25 is 4.5km the ammunition 23 will be deflected further from the target by the decoy 1 than if the said distance is 2.5 km.

7 Figure 2 shows the decoy 1 with the radiator 9 positioned on a movable target 25, such as the top of a vehicle.

The structure of the decoy 1 is shown in Figure 3. A detector unit 2 on the target 25 is electrically connected to a o5 subsequent electronic evaluation and control unit. Through a cable 4 the evaluation and control unit 3 is connected to the diversionary laser 5. Optically connected to the laser 5 in the decoy 1 is a coupling lens 6, an optical fibre 7 situated in an extensible (for example 3 - 4 m vertically adjustable) mast 8, io and also the radiator 9. In this system the detector unit 2 is always mounted on the target 25, while the other subassemblies may be separate from the target 25.

The manner in which the decoy 1 operates is illustrated with reference to Figure 4.

The radiation 21 directly incident on the target 25 or the reflected scattered laser radiation 24 from the laser signal 21 emitted by the laser target illuminator 20 is detected by the laser detector 2 having appropriately mounted individual detectors 2.1 to 2.8. According to the local surroundings of the target 25 two or three detectors 2 normally prove adequate. For preference, however, 8 detectors 2 are employed, in order to obtain a useful aperture angle of up to 6011, owing to the detector field of the ammunition unit 23. The laser signal 21 and/or 24 is converted in this process into an electrical signal and passed to the electronic evaluation and control unit 3. In 8 the electronic evaluation and control unit the angle with respect to the target illuminator 20 and laser pulse are determined by a signal analysis unit 3.1. The wavelength of the laser is likewise analysed, for example by means of interference. This is important in order to ensure the correct choice of laser. The laser pulse code thus determined and the wave length are passed via the cable 4 to the diversionary laser 5, for example a NEODYM YAK, in order to activate the latter. Thesignal analysis 3.1 is the means of ensuring that the laser pulse code io received will be equal to the code emitted by the radiator 9.

This is effected by adjusting the laser intensity and frequency (pulse train) of the diversionary laser 5 by means of the evaluation and control unit 3. This laser energy is passed into the optical fibre 7 by means of the optical coupling unit 6 1.5 and emitted direct to the ammunition unit 23 through the radiator 9 as a laser beam 24'. The ammunition 23 is thus directly illuminated by the laser beam 24'of the decoy 1. The decoy 1 is supplied with power through the electrical input 12 shown in Figure 4. The lines 12.1 and 12. 2 are the internal current supply to the decoy 1. An additional interface 11 of the decoy 1 is connectable to further units of apparatus. The information from the electronic evaluation and control system 3 can thus be-supplied by means of the interface 11 to a tracking system, (not shown) so that the laser target illuminator 20, for example, can be automatically neutralised. For this purpose 9 the angular range determined using the electronic evaluation and control unit 3 with respect to the laser target illuminator 20 is put to further use for determining the solid angle and the radiation angle, displaced therefrom to the maximum, for the o-5 laser beam 24', as a known quantity. By conventional angle decoding processes, it is possible from the angular range thus determined, to find the angle and the distance from the laser target illuminator 20. It is also possible, however, for the angular range to be passed direct to a visual and information lo system, not shown, in the target 25, where it is received, for example, by an optical/electronic system, adjusting the visual range of this system to the direction indicated.

Claims

1. A method for the deception of terminally guided ammunition controlled using a laser beam which marks a o.5 target from which radiation is reflected or dispersed, in which method a decoy apparatus adjacent the target is activated after the target has been acquired by the beam of a laser target illuminator, said decoy generating a laser beam of higher energy and with the same pulse repetition rate and wave length io as the laser beam reflected from the target, which is transmitted direct to the ammunition whereby the said ammunition is guided by a spatial displacement of the decoy along a flight path away from the illuminated target.

2. Method in accordance with Claim 1, wherein the decoy laser beam is emitted with a maximum offset of one pulse with respect to the laser beam of the target illuminator.

3. Method in accordance with Claim 1 or 2, wherein the laser beam radiator of the decoy is positioned within a radius of up to 100 m from the target and exerts a deceptive influence on the ammunition unit.

4. Method in accordance with Claims 1 to 3, wherein the reflected laser beam is used in the production of the decoy laser beam.

5. Apparatus wherein a decoy device comprising a detector unit associated with the target is connected to an evaluation and control unit and the output thereof is connected by a cable with a laser having a radiator positioned above or to the side of the target, the radiator being coupled by an optical fibre and an optical coupling unit to the decoy laser.

io

6. Apparatus in accordance with Claim 5, wherein the radiator of the decoy laser is mounted on a vertically adjustable mast.

7. Apparatus in accordance with Claim 5 or 6, wherein the radiator of the decoy laser is positioned within 100 rn of the target.

8. Apparatus in accordance with any one of Claims 5 to 7, wherein the decoy device is electrically connected through an interface unit with, an electronic evaluation and control unit.

9. Method for the deflection of terminally guided projectiles from an intended target carried out as described herein and exemplified.

10. Apparatus constructed and arranged to function as described herein and exemplified in the drawings.

CLAIMS 1 A method for the deception of terminally guided ammunition controlled using a laser beam which marks a target from which radiation is reflected or dispersed, in which method a decoy apparatus associated with the target is activated after the target has been acquired by the beam of a laser target illuminator, said decoy generating a laser beam of higher energy and with the same pulse repetition rate and wave. length as the laser beam reflected from the target, which is emitted direct to the ammunition whereby the said ammunition is guided along a flight path away from the illuminated target as a result of the spacing of the decoy laser beam emitter from the target.

2. Method in accordance with Claim 1, wherein the decoy laser beam is generated with a maximum offset of one pulse with respect to the laser bealm of the target illuminator.

3. Method in accordance with Claim 1 or 2, wherein the laser beam emitter of the decoy is positioned within a radius of up to 100 m from the target and exerts a deceptive influence on the ammunition unit.

5. Apparatus for carrying out the method of any preceding claim, wherein a decoy device comprising a detector unit associated with the target is connected to an evaluation and control unit and the output thereof is connected by a cable with a decoy laser generator positioned above or to the side of the target, the generator being coupled by an optical fibre and an optical coupling unit to the decoy laser beam emitter.

6. Apparatus in accordance with Claim 5, wherein the decoy laser beam emitter is mounted on a vertically adjustable mast.

7. Apparatus in accordance with Claim 5 or 6, wherein the generator and the decoy laser beam emitter are positioned within 100 m of the target.

8- Apparatus in accordance with any one of Claims 5 to 7, wherein the decoy laser generator is electrically connected through an interface unit with an electronic evaluation and control unit.