GB863648A - A history-indicating radar system - Google Patents

Abstract

863,648. Pulse radar. RAYTHEON CO. May 8, 1958 [May 9, 1957], No. 14822/58. Class 40(7) In mobile radar apparatus. the video echo signals are recorded by modulating an electron beam in an information-storage device having a storage surface swept by the beam, whose sweep axis is moved in correspondence with the vehicle's course and speed. The stored information is read into a display tube thus affording a display of the recent history of target positions, and may be of the same form as that stored or may be a relative bearing display. In a ship's pulse radar, transmitter 4 provides a synchronizing pulse to trigger switching matrix 6 and plan-position-indicator (P.P.I.) sweep generator 7. Azimuth stabilizer 15 produces a signal representing the angle between the instantaneous direction of the radiated beam and true north and a resolver applies corresponding quadrature signals to sweep generator 7 to cause the radial trace to rotate such that the position on the face of storage tube 10 corresponding to true north is stabilized. The electrical centre of the storage tube P.P.I. sweep is moved in correspondence with the ship's course and speed by two off-centering voltages from "true motion" unit 16 impressed on to deflection coils 9 through amplifier 8. The video echo signals from amplifier 13 are gated in each radar recurrence period for a time corresponding to the radar range required and are written as an electrostatic charge pattern on tube 10, this information being read out spirally by sweep generator 20 for application to short-persistence display tube 12. It is arranged from switching matrix 6 that amplifier 13 is prevented from passing signals for a period of thirty seconds in every 6¢ minutes the track of a moving object on the display thus being broken and the speed thereof ascertainable from a measurement of a "dash" length in nautical miles. Whilst signals are being written in the storage tube range rings 34 from generator 18 are displayed on tube 12. After the termination of the writing period matrix 6 causes spiral sweep generator 20 to read out the stored information for application to display tube 12, also scanned spirally, and to disable the range ring generator. By manipulation of knobs 21, 22 the centre of the P.P.I, sweep is caused to move vertically and horizontally and thus the displayed point representing the ship is maintained on the storage and display tubes. In a modified display the ship's position is displayed centrally and the displayed ship's heading is at the zero mark at the top of the tube thus affording a relative form of display, Fig. 3 (not shown); in this case the range in the display is made one-half that in the storage tube.