GB2356034A

GB2356034A - Missile decoy system

Info

Publication number: GB2356034A
Application number: GB8713360A
Authority: GB
Inventors: Clive Ian Coleman
Original assignee: GEC Marconi Ltd; Marconi Co Ltd
Current assignee: BAE Systems Electronics Ltd
Priority date: 1986-06-18
Filing date: 1987-06-18
Publication date: 2001-05-09
Anticipated expiration: 2007-06-18
Also published as: GB2356034B; GB8614818D0; GB8713360D0; GB2356034A8

Abstract

A system for decoying missiles which use thermal imaging sensors to home in on their targets. An infrared image of a ship 4 or other threatened body is projected onto a smoke screen and moved across the screen so as to lead the missile away from the target. The means for projecting the image may comprise an infra-red laser and servo-controlled mirrors housed in a buoy 1. The buoy may be launched from the ship in response to detection of an approaching missile and may incorporate a radar decoy.

Description

2356034 Nissile Decoy System This invention relates to decoy systems for

missiles incorporating imaging sensors. Infrared missile seekers which use imaging sensors rather than single "hot-spotm detectors present a serious threat to potential targets such as warships. Conventional infrared decoys such as flares and modulated heat sources are totally ineffective against these advanced seekers. Imaging sensors may operate in the visible band too. An object of this invention is to present an image of a ship or other platform under threat, to act as a missile decoy.

According to one aspect of the invention a decoy system for decaying missiles incorporating imaging sensors comprises means to generate an image representing a target to be protected and means to project said image onto a projection screen remote from the target. The means to generate the image may comprise a source of radiation, such as a laser, arranged to illuminate a representation of the target, the representation being transparent to that radiation. Preferably the position of the image on the screen can be controlled so as to move the i1nage away from the target and thereby deflect the missile. This may be achieved by one or more servo-controlled -2mirrors, for example.

For use particularly with anti-ship missiles, the means to generate and project the image may be housed in a buoy. The buoy may be radio controlled, or pre-programed to follow a course in the water. The buoy is preferably rocket launched from the target ship in response to detection of an approaching missile. The buoy may additionally incorporate a radar decoy.

The decoy system preferably includes means to generate a smoke screen to constitute the projection screen. The smoke screen may incorporate material to enhance its reflectivity.

According to another aspect of the invention, in a method of decoying a missile having imaging sensors, an image representing the target is projected onto a screen remote from the target and moved away from the target, thereby to deflect the missile. The method may be for decaying an infrared seeking anti-ship missile and may comprise the steps of launching from a target ship, on detection of an approaching missile, a projector mounted on a buoy, and generating a smoke screen, the projector being arranged to project an infrared image of the target ship onto the smoke screen.

One embodiment of the invention will now be described with reference to the accompanying drawings of which:- Figure 1 shows a plan view of the missile decoy system employed to protect a ship; Figure 2(a) shows an image projector of the system; Figure 2(b) shows a transparency carrying an image of the target to be protected; and Figure 3 shows a buoy on which the projector is mounted.

Referring to Figure 1, an infrared-seeking missile (not shown) approaches its target, a ship 4, along a trajectory 5. A smoke screen hangs between the ship and the oncoming missile and a thermal (i.e. infrared) simulated image 2 of the target 4 is projected from a buoy 1 onto the smoke screen.

The smoke screen is generated in response to a missile approach warning provided by a system not shown but mounted on the target ship or other 'friendly' platform. This warning system may give a crude bearing of the missile direction, perhaps within 45% The smoke screen shields the ship 4 by obscuring the infrared target, but in itself is unlikely to deflect the missile off course since the missile might already be travelling in the right direction before any smoke is generated and, on losing target lock, will simply continue on that course; alternatively,.the missile may have a further homing mode (e.g. radar guided) which would be less susceptible to obscuration by the smoke screen and would take over if infrared homing were denied.

A decoy image is provided by a projector 15, launched on a buoy 1 from the ship 4. An infrared image representing the target is projected onto the smoke screen at an initial position 2, and then by controlling the buoy, moved away from the ship. The missile's infrared seeker picks up the thermal signal from the image, recognises it as a ship and tracks it as it moves away along the smoke screen. The image is moved off to a final position 3 such that the incoming missile is deflected well away from the target ship, or any others in the area.

The thermal image projector is shown in Figure 2a. The projector 15 consists of an infrared laser 8, beam formi,ng optics 9 for illuminating a transparency 10 and beam projecting optics 11 to project the image beam towards some means (not shown) for controlling its direction. The laser 8 might be, for example, a C02 laser emitting at about 10 micrometres. Suitable material for the optics 9 and 11 would be germanium or zinc sulphide or other infrared transparent material. The "transparency" is shown in Figure 2(b), consisting simply of a likeness of the ship 4 cut out of a metal sheet; it need not have very high reoslution, but the sheet should be a reasonably good conductor for thermal reasons.

The projector 15 is mounted in a powered and radio controlled buoy 1, as shown in Figure 3. The beam is projected by way of two servo controlled mirrors 16. The projector is radio-controlled to rotate and thereby move the image on the smoke screen away from the target ship, by radio control means 17. Alternatively the servo controlled mirrors may be controlled to move the target image on the smoke screen. The mirror control also acts to stabilise the image position, as the buoy bobs in the water. The image position control means may be pre-programed to rotate as required.

The buoy should be capable of being rapidly deployed; it is therefore rocket-launched in response to a signal from a missile approach warning. The whole decoy system can be simply automated to co-ordinate the missile approach signal, smoke screen generation, buoy deployment, projector control and image 'walk-off', taking into account wind strength and direction, the ship's course and other ship location information. As an alternative to radio control, the buoy could be loaded with a 'prelaunch' message controlling its off-target travel.

Possible refinements of the system include augmenting the reflectivity of the projection screen by the use of appropriate aerosols or reflective chaff, and providing some laser power, via a frequency doubler, at about 5 micrometres, so that 3-5 micrometres or dual infrared band seekers are also defeated. Alternatively a thermal infrared source could be used to provide illumination in the 3-5 micrometres band. A radar transmitter could be incorporated in the buoy, to provide a radar decoy in addition to and independent of the infrared decoy.

As an alternative to controlling the projector or the mirrors to move the projected target image, the buoy can be steered through the water by radio control, or by a pre-programmed motor.

High winds could affect the launch of the buoy but, as in any fire control system, wind speed and direction are taken into account. However it will be appreciated that high positional accuracy -5is not necessary for this system.

The system is equally useful on land, where infrared seeking missiles may be directed against buildings and vehicles. Again, the mirror system or projector is controlled to move the simulated target on a smoke screen, or the projection apparatus may be housed in a remote controlled vehicle which can be steered away over the land, moving the image as it travels.

Claims

-6CLAINS A decoy system for decoying missiles incorporating imaging sensors, comprising means adapted to generate an image representing a target to be protected, and means adapted to project said image onto a projection screen remote from said target. 2. A decoy system according to Claim 1, comprising means adapted to control the position of the image on said screen, allowing the image to be moved away from said target thereby to deflect the missile. 3. A decoy system according to Claim 1 or 2 wherein said means adapted to generate an image comprises a source of radiation arranged to illuminate a representation of the target, said representation being transparent to said radiation. 4. A decoy system according to Claim 3 wherein said radiation source is an infra-red laser. 5. A decoy system according to Claim 2. 3 or 4 wherein said means adapted to control the position of the image comprises an. arrangement of servocontrolled mirrors. 6. A decoy system according to any preceding claim and adapted to be movable by remote control. 7. A decoy system according to any preceding claim including means adapted to generate a smoke screen to constitute said projecton screen. 8. A decoy system according to Claim 7 wherein said smoke screen incorporates material to enhance its reflectivity. -7 9. A decoy system according to any preceding claim mounted in a buoy and adapted for use against anti-ship missiles. 10. A decoy system according to any preceding claim incorporating a radar decoy. 11. A method of decoying a missile having imaging sensors wherein an image representing a target is projected onto a projection screen remote from said target and moved away from said target, thereby to deflect the missile. 12. A method according to Claim 11 comprising the step of generating a smoke screen to form said projection screen. 13. A method according to Claim 11 or 12 for decoying an infrared seeking anti-ship missile comprising the steps of launching from a target ship, on detection of an approaching missile, a projector mounted on a buoy and projecting an infrared image of said target ship onto said projection screen. 14. A decoy system substantially as hereinbefore described with reference to the accompanying drawings.

1 15. A method of decoying a missile having an imaging sensor, substantially as hereinbefore described with reference to the accompanying drawings.

f Amendments to the claims have been filed as follows A decoy system for decaying missiles incorporating imaging sensors, the system comprising means for deploying a particulate screen in space and means for projecting an image of a target to be protected on to said screen remote from said target.

2. A decoy system according to Claim 1, comprising means adapted to control the position of the image on said screen, allowing the image to be moved away from said target thereby to deflect the missile.

3. A decoy system according to Claim 1 or 2, wherein said means for projecting an image comprises a source of radiation arranged to illuminate a representation of the target, said representation being transparent to said radiation.

4. A decoy system according to Claim 3 wherein said radiation source is an infra-red laser.

5. A decoy system according to Claim 2, wherein said means adapted to control the position of the image comprises an arrangement of servocontrolled mirrors.

6. A decoy system according to any preceding claim and adapted to be movable by remote control.

7. A decoy system according to any preceding claim, wherein said means for deploying a particulate screen in space comprises means for disposing a smoke screen in space.

8. A decoy system according to Claim 7 wherein said smoke screen incorporates material to enhance its reflectivity.

11 -. ----4. -

9. A decoy system according to any preceding claim mounted in a buoy and adapted for use against anti-ship missiles.

10. A decoy system according to any preceding claim incorporating a radar decoy.

11. A method of decoying a missile having imaging sensors wherein a particulate screen is disposed in space and an image representing a target is projected onto the screen remote from said target and moved away from said target, thereby to deflect the missile.

12. A method according to Claim 11 comprising the step of generating a smoke screen to form said screen.

13. A method according to Claim 11 or 12 for decoying an infrared seeking anti-ship missile, comprising the steps of launching from a target ship, on detection of an approaching missile, a projector mounted on a buoy and projecting an infrared image of said target ship onto said screen.

14. A decoy system substantially as hereinbefore described with reference to the accompanying drawings.

15. A method of decoying a missile having an imaging sensor, substantially as hereinbefore described with reference to the accompanying drawings.