Patent GB-710295-A (GB)
Title: Improvements in or relating to radar system and method
IPC: G01S7/282
Filed: 1951-10-23
Abstract: 710,295. Radar. GILFILLAN BROS., Inc. Oct. 23, 1951 [Dec. 29, 1950], No. 24702/51. Class 40(7) In a pulse radar system having a scanning directive aerial system means are provided deriving a continuously varying voltage in accordance with the scanning movement and therefrom obtaining pairs of pulses spaced in time in accordance with the instantaneous magnitude of the voltage and means at a remote location are used to recreate the voltage from the pulse pairs for use in a remote indicator. The embodiment described consists of a Ground Control Approach system with a remote indicator. Radar pulses are radiated for alternate scanning periods by elevation antenna 10 and azimuth antenna 11, energy being supplied by transmitter 33 under control of pulse synchronizer unit 20 and fed to one or other of the aerials under control of switch device 36, 37, 38, 39. T.R. switch 40 is connected between the aerial and receiver 41. Voltages are generated in angle voltage generators 10B and 11B, mechanically coupled to the aerial systems, in accordance with the aerial position and the effective aerial position voltage is fed over relay 13 to amplitude comparator 14. Relay 13 is controlled by switch device 46 associated with the aerial system. Comparator 14 forms part of information transmission device 26 which receives synchronizing pulses from synchronizer 20 and' uses these to generate 250 Á sec. gate pulses 48. These pulses are differentiated at 49 and the positive peaks 50 selected at 52 and applied as reference pulses 30 to one transmission line 21. Pulses 30 are also applied to trigger generator 53 producing 200 sec. negative pulses 54. These pulses control saw-tooth generator 55 the output 56 of which is applied to comparator 14. The output of the comparator is a positive pulse 57 commencing at the instant when the voltage of the sawtooth generator output corresponds to the voltage from effective aerial angle voltage generator. Pulse 57 is differentiated at 58 and the front edge pulse 60 selected at 61 and transmitted as pulse 31 over line 22. The spacing between reference pulse 30 and variable pulse 31 is a measure of the aerial angle voltage. At the indicator reference pulses 30 are reshaped and inverted in unit 90 to produce negative reference pulses 92 and 93. Pulses 31 are reshaped in unit 91 to produce positive pulses 94. Pulses 92 and 94 gate generator 95 to produce a negative pulse 96 having a duration equal to the time interval between the received pulses 30, 31 and this initiates the operation of saw-tooth generator 97 which generates a saw-tooth of constant slope and a duration equal to that of pulse 96. The maximum value of the saw-tooth is thus linearly related to the spacing of pulse 30, 31. The sawtooth waveform is peak detected at 97 and a storage stage 98 is used to maintain the detected voltage until the arrival of the next pulse 30 as determined by the release pulse 93. D.C. level setting stage 99 and gated clamping circuit 101 assist in transforming the output voltage into one corresponding as nearly as possible to that fed in over relay 13 and a feedback path 102 including phase shifter 103 prevents lag in the operation of the integrating assembly. The reconstituted aerial position voltage is fed over relay 27, operated in synchronism with relay 13 by means of the connections shown, to remote radar indicator 15. Blanking and synchronizing signals from the aerial switches 45 and 46 are also fed directly to the indicator as are the transmitted and received radar pulses. The circuits of units 14 and 58 are described with reference to Fig. 2 and of the units within the dotted line 23 with reference to Fig. 3 (Figs. 2 and 3, not shown).