The present invention will now be described by way of example only and with reference to the accompanying drawings, of which:
FIG. 1 shows an example of the present invention in use.
FIG. 2 shows a second example of the present invention in use.
FIG. 3 shows a third example of the present invention in use.
FIG. 4 shows a fourth example of the present invention in use.
FIG. 5 shows a fifth example of the present invention in use.
FIG. 1 shows an aircraft 1 flying at a distance from target 2. The aircraft 1 is utilising an on-board Synthetic Aperture Radar which has field of view 3. The Synthetic Aperture Radar determines the position and orientation of the aircraft. A single aperture is used to generate the beam for both the Synthetic Aperture Radar and Radar Information Field 4, to minimise alignment errors. The aircraft 1 has released an air-to-surface missile 5 which is guided towards the target 2 by the Radar Information Field 4. The Radar Information Field 4 controls the angular and spatial position of the missile within its beam, steering the missile. The Radar Information Field and/or the Synthetic Aperture Radar may be used intermittently to lessen the risk of detection and/or corruption by electronic countermeasures.
FIG. 2 shows the aircraft 1 flying over terrain 6. The aircraft 1 is utilising an on-board Synthetic Aperture Radar with field of view 3 as described above. This time the Radar Information Field 4 is generated outside of the field of view 3 of the Synthetic Aperture Radar. The Radar Information Field 4 guides an unmanned air vehicle 7 over the terrain 6 at a distance from the aircraft 1. In this case the Radar Information Field is pulsed to save energy and to minimise the risk of detection and/or interference. The pulse rate must meet the guidance update requirements of the unmanned air vehicle so that it is sufficiently accurately guided and does not drift outside of the Radar Information Field beam in between pulses.
FIG. 3 shows the aircraft 1 flying over terrain 8. The aircraft is utilising an on-board Synthetic Aperture Radar with field of view 3 as described above. The aircraft 1 has released an air-to-surface missile 9 which is initially guided towards the target 10 by the Radar Information Field 4. The aircraft 1 does not have line-of-sight to the target 10 and so the Radar Information Field 4 cannot guide the missile 9 all the way to the target 10. Instead, the Radar Information Field 4 is used to guide the missile 9 as far as possible towards the target 10, and then the missile 9 may rely on its internal inertial navigation equipment or other means such as following a ballistic trajectory to reach the target 10. The dotted line shows the path of the missile 9.
FIG. 4 shows a helicopter 11 which is utilising an on-board Synthetic Aperture Radar which has a field of view 3 as described above. The helicopter 11 is flying over terrain 12, and is guiding a tank 13 across the terrain 12. The helicopter 11 is using a multi-function radar to act as both a Synthetic Aperture Radar and a tracking radar, having tracking beam 14, for tracking the tank 13. The tracking radar establishes the position of the tank 13 relative to the helicopter 11. The helicopter 11 communicates with the tank 13 by means of a command link, which allows a radio frequency signal to be transmitted from the helicopter 11 to the tank 13. This signal provides guidance information to the tank, and is denoted by the dotted line 15. Signals other than radio frequency signals could be used instead, for example modulated laser signals.
FIG. 5 shows an aircraft 1 which is utilising an on-board Synthetic Aperture Radar for locating a target 20. The Synthetic Aperture Radar has a field of view 3 and illuminates the area around the target 20. A missile 16 has been released by the aircraft 1 or by a nearby aircraft, with the objective of hitting the target 20. The seeker 17 of the missile 16 receives the radar returns (denoted by images 18), and the received signal is processed on-board the missile 16 to generate an electromagnetic image of the target 20 and surrounding area 19 for comparison with images of the target and/or surrounding terrain contained within an image library stored within the missile 16. Where target image data is not available, the imagery of a terrain feature located at a known position with respect to the target may be known, and this feature image together with target offset data may be used to guide the missile to the target. Where a direct line of sight to the target is not available, a location visible by line of sight may be illuminated instead and data defining the position of that location with respect to the target should be provided to the missile.
Patent Application
20080012751
