GB599554A - Improvements in or relating to radar systems - Google Patents

Abstract

599,554. Radiolocation ; thermionic distributers. WEBLEY, R. S., and ROBSON, J. M. May 2, 1945, No. 11197. [Class 40 (v)] In a pulse radar system of the kind described in Specification 598,649, wherein the main reception lobe of the directional receiver performs a continuous conical scan and traverses four predetermined positions in its orbit coincidently with the transmission of exploring pulses, means are provided for deriving in separate channels substantially continuous D.C. voltages dependent on the intensities of the signals received at the successive lobe positions, the means comprising for each channel a condenser which is charged through a thermionic valve and discharged through a high resistance, each valve being rendered conductive in turn as the lobe passes through successive ones of the four predetermined positions. The echo signals are applied to the control grid of the valve V1, to the suppressor grid of which is applied a strobe pulse for selecting signals from objects at a particular range. The voltage at the anode of VI varies, during the strobe pulse interval, in accordance with the signal amplitude, so that when a suitable signal is received the cathode of diode V3 falls until the bias applied to it is overcome, whereupon it conducts and C3 is charged to an extent depending on the signal received under the strobe. When V1 is cut off again, the charge on the condenser leaks away with a time constant of 400 microseconds. A pulse shaping circuit is placed between the cathode of V3 and the grid of valve V4 so that a lengthened symmetrical pulse of amplitude corresponding to the signal under the strobe is obtained. The output voltage from the valve V4 is applied through condensers C5, C6, C7, C8 to the anodes of double-triodes V5, V6. Two switching waves in phase quadrature are applied to the grids of V5 and V6 from input terminals 44, 45, 46 at the frequency of the conical scan, so that the four triodes of valves V5, V6 become conducting in succession when the lobe is in its predetermined positions. Each of the condensers C5, C6, C7, C8 becomes charged, in succession, as the corresponding triodes conduct, to an extent depending on the signal under the strobe at that position of the reception lobe, and then when the triodes cease conducting the charge leaks away through high resistances connected in parallel with the valve. The mean D.C. potentials at the anodes of the valves which are taken to the outputs 71, 72, 73, 74 are consequently proportional to the signals received in the four predetermined positions of the reception lobe. The output D.C. voltages are employed for the display of elevation and bearing alignment, for automatic correction of the elevation and bearing and for automatic gain control as described in Specification 599,389.