Patent GB-1002031-A (GB)
Title: Improvements in or relating to radar systems
Inventor: WATT JAMES
IPC: G01S7/12
Filed: 1961-04-18
Abstract: 1,002,031. Pulse radar. MARCONI'S CO. Ltd. March 27, 1962 [April 18, 1961], No. 13945/61. Heading H4D. A radar system comprises means deriving at a low periodicity (e.g. one per minute) a succession of sets of information each set being the direction and range of targets, a plurality of storage means, means for cyclically storing a sequence of the derived information sets in the storage means with a different sequential set in each, means for taking off cyclically at a relatively high repetition rate (e.g. 2À5 seconds) the information sets stored at any given time in the storage means, and means utilizing the information taken off to produce a final P.P.I. display. The information sets may be taken off cyclically and sequentially, or simultaneously: and the derived information may be the compass direction and distance of targets. The final display is either of the " relative motion " or of the " true motion" kind; in the latter case the preferred arrangement is such that the last position of the radar displayed at any time is always at a predetermined position on the display surface. Relative motion display, Figs. 1, 2 a, b.-A conventional scanning pulse radar feeds echo range and bearing data to an " intermediate " P.P.I. display tube 5 having no afterglow and controlled by the ship's gyro compass to compass-stabilize the display to " north-upwards." Storage-type camera tubes C1, C2, C3, utilizing television raster scanning, are exposed successively at one minute intervals to one complete P.P.I. scan (e.g. three seconds) on tube 5, each camera tube holding its information for three minutes at the end of which its storage is erased and a new picture is stored. The camera tube outputs are fed to switches SC1, SC2, SC3 having rotors rotating in synchronism with the radar aerial scan and at one revolution per three minutes; the switches feed a switch CD the rotor of which rotates at one revolution per 2¢ seconds. Switch CD has one stator contact occupying some 180 degrees and this contact is connected to tube C3 which is at the time considered televising the latest picture. The output of switch CD intensitymodulates display tube FRC which is subjected to line and frame deflection in synchronism with that of the camera tubes. The ensuing display is as indicated by Figs. 2a, 2b, which are separated by a four-minute interval, for " own ship " A steaming north; B is a ship steaming west and C is a fixed target. True motion display, Figs. 1, 2, c, d.-The above " relative " display is transformed into a true motion display, Fig. 2 (c), (d), by signals from a resolver R fed from ship's log L. Means not described may insert estimated drift. Storage capacitors NK1-NK3, for the northerly component of speed, and EK1-EK3, for the easterly component of speed, are utilized; the operation of the circuit is explained in detail in the Specification. The outputs of amplifiers NA, EA are fed via a switch RTM to respective shift coils of tube FRC. For the " relative " display the data from the camera tubes may be taken off simultaneously Fig. 3 (not shown).