GB1325162A - Device for accurately measuring the position of a distant object - Google Patents

Abstract

1325162 Missile guidance SOC D'ETUDES ET DE REALISATIONS ELECTRONIQUES 12 Oct 1970 [13 Oct 1969 10 April 1970] 48398/70 Heading H4D In an optical missile guidance system, an image disector tube 31, Fig. 3, has its field of view visually centred on the target 27. The image, including the missile 34 is raster scanned, firstly with the line direction vertical to give the x co-ordinate of the missile's position with respect to the central target, and then with the line direction horizontal to give the y co-ordinate. In the first x scans, the disector output d, Fig. 2, includes responses (i 1 -i n ) due to fixed objects and response i x due to the missile. The former remain fixed in the next x scan (i<SP>1</SP> 1 -i<SP>1</SP> n ) and are cancelled out by delaying the first scan responses by two field periods and subtracting them from the present responses. Similar action with successive y scan responses (j x , j 1 -j n ) and (j<SP>1</SP> 1 , j x , j<SP>1</SP> 2 -j n ) remove the fixed responses to leave the missile response. The response i<SP>1</SP> x and j<SP>1</SP> x position are converted to x and y co-ordinates by pulse counting techniques. The co-ordinate signals are fed as flight correction signals to the missile. The image of the target may be optically enlarged by means 32 as the missile nears the target. The operator views the missile and target by means of the same optics as the image disector. Mirror 22 is gyroxopically controlled by joystick 28, and position defining signals are fed to the guidance system gyros 29, 30. The image director and scanning circuitry may be carried by the missile (Fig. 4, not shown), the position co-ordinates of the target within its field of view being transmitted towards the ground, from whence flight correction signals are transmitted back. A laser may be substituted for image disector 31 for illuminating the target. The system can be used as a star tracker.