The target object evaluation device for marine radar system by means of water -

摘要

1432448 Radar IOTRON CORP 13 April 1973 [13 April 1972] 17927/73 Heading H4D An evaluation apparatus for use with a marine surface radar comprises means providing, at successive azimuth positions of the radar beam, signals representing the near edge of a target, signals representing the far edge of the target and a target envelope end signal when the near and far edge signals coincide. Ships 402, 404, 405, buoy 406 and landmass 407, Fig. 2 all reflect pulses from a continuously rotating radar antenna mounted on the ship. Target 405 will not normally be displayed. On each radar scan, the echoes from radar 110 are processed by evaluation apparatus 112, Fig. 4. S-bits and E- bits are generated and stored to represent the near and far edges of the target envelope. An S-bit is generated after three positive returns from the same range from three consecutive azimuth steps. An E-bit is generated at the first subsequent non-return in any azimuth step in which an S-bit has been generated. As the radar beam sweeps the target, the E- and S- bits trace out the target envelope (Fig. 5, not shown) and coincidence of the E- and S-bits following two consecutive non-returns at the envelope range, signals the end of the target. The number of S-bits generated indicates the target width and this is compared in computer 114 to a predetermined range-dependent number representing the angular width of the largest ship likely to be encountered (e.g. 2000 feet). If the target is wider, the target is designated a landmass, if not it is labelled as a possible ship. Information on the target range, width and land/ship identity is passed to computer 114 which determines whether this target has previously been identified. If yes, the target velocity and heading are calculated using the old and new positions. If not previously encountered, the new target is stored for further use. The position of the target is determined as the centre of the envelope and the ship target is displayed there as an open circle, while landmass targets are displayed as a broken line extending along the near edge (Fig. 3, not shown). The ship velocity and heading are indicated by a vector line drawn from the target circle on the display. The Specification shows detailed diagrams of the digital circuits included in the evaluation apparatus 112 and details of computer programs for digital computer 114 for reading in data from evaluation unit 112 and radar 110, target identification and tracking and display control (Figs. 13-15, not shown). Reference has been directed by the Comptroller to Specification 1,337,966.