GB1372348A - Automatic sight and tracker harmonisation - Google Patents

Abstract

1372348 Photo-electric guidance BRITISH AIRCRAFT CORP Ltd 4 Nov 1970 [4 Nov 1969] 54000/69 Heading H4D In a missile guidance system in which the operator moves a telescope to follow a target, and a light source associated with the missile is tracked by a tracker including a vidicon, collimation error between the telescope and tracker is corrected by performing an initial nulling operation which subsequently results in compensation of such error in use of the system. The tracker detects offset angle and offset distance of the missile from the line of sight to the target and transmits correcting signals. During performance of the nulling operation, light from a small source lamp 25 (Fig. 1) provides an image I on the screen 21 of the vidicon of the tracker 16. At the tracker output terminals 38, 39 (Fig. 2) voltages appear which are proportional to the co-ordinates of the displaced image relative to the electrical centre of the screen, the displacement being due to the collimation error. These voltages are supplied, via switches 42, 43, to integrator circuits 34, 35 where capacitors 32, 33 charge up to store the voltages. During capacitor charging, the outputs of the circuits 34, 35 are fed back, via loops 40, 41, to the terminals 38, 39 to reduce the inputs to the circuits 34, 35. When these inputs are reduced to zero, the nulling operation is complete and switches 42, 43 are opened. Since the charges stored on the capacitors 32, 33 are still applied to the terminals 38, 39 they result in reduction of any voltages appearing at these terminals from tracker 16 during following of a missile, thus compensating for any collimation error, between the tracker and telescope, in the missile following signals. As shown the tracker and telescope are mounted in a common container 1 supported in gimbals. During missile following, light from lamp 25 is prevented from reaching screen 21 by interposition of a small, opaque disc 47. The light of lamp 25 still enters the telescope to form a graticule. The light source associated with the missile may be its own exhaust and, possibly, an additional beacon.