GB1177632A - Improvements relating to Systems for Tracking Moving Objects. - Google Patents

Abstract

1,177,632. Spatial filtering. BRITISH AIRCRAFT CORP. Ltd. April 18, 1967 [Jan. 21, 1966], No.2970/66. Heading G2J. [Also in Division H4] In a tracking system a "transform pattern" filter arrangement is inserted in the path of light from the scene (or its image) containing the missile and target, the filter arrangement eliminating light patterns other than those originating from the missile and target, and an output signal is generated representing the position in the object plane of the light patterns passed by the filter. A transform pattern filter for the missile can be prepared in advance; to prepare such a filter for the target, a variable field stop 6 is adjusted until only the target pattern is passed and a transform of this is photographed to produce the target filter. An additional filter representing the characteristics of the missile or the target can be inserted periodically into section 8 to produce a modulation enabling missile and target to be distinguished. A servosystem may be added to keep the target on the optical axis. Detector 11 is a closed circuit television camera or a matrix of photo-electric detectors. In a single-filter arrangement a filter Fl selecting only missile information is prepared by projecting a Fourier transform of the missile on to a photographic plate; a second filter F2 is made by adjusting stop 6 until only light from the target is present and projecting a Fourier transform thereof on to a photographic plate; a filter F1' complementary to filter F1 and a filter F2' complementary to filter F2 are prepared; filters F1', F2' are combined to produce a filter F12'; and a filter F12 complementary to filter F12' is prepared and utilized in the system. Field stop size may be programmed to allow for increasing oncoming target image with time. In another embodiment the light from the field stop is split into two parts one of which passes through the above filter F1 and the other through the above filter F2, separate detectors being utilized.