Tracking link

Abstract

In a system (10) comprising a trunnion-mounted aiming device (11) and a trunnion-mounted sighting device (14) interconnected by a tracking link (13) and having an associated visual display (16) providing an image of the field of view containing the sight line (15) of the sighting device (14) there is provided a means of accurately positioning an aiming mark designating the pointing direction (12) of the aimed device (11) in the visual display (16). This positioning arrangement is provided by an elevation sensor (18) associated with the aimed device (11), an elevation sensor (19) associated with the sighting device (14), an electronic indicator mark generator (28) and an electronic processor (20), the latter being operable according to the measurements from the sensors (18,19) to deflect the mark generated by the generator (28) so as to compensate in the elevation axis for backlash and inertia of the link (13) and in the traverse axis for lack of parallelism of the trunnion mountings of the devices (11,14). The indicator mark may be generated by a CRT (28,40) in relation to which the processor (20) controls the X and Y drive circuits. Alternatively the processor (20) may generate video bright-up pulses in the raster scan of a scanned raster device forming part of the visual display (16).