Patent GB-597977-A (GB)
Title: Improvements in or relating to electronic valve circuits
IPC: G01S1/02
Filed: 1945-10-23
Abstract: 597,977. Valve circuits ; radiolocation. GIRLING, F. E. J. Oct. 23, 1945, No. 27971. [Class 40 (v)] [Also in Group XXXV] In a synchronized time base circuit, the time base voltage is automatically controlled to reach a predetermined level at the time of a recurrent input occurrence, which has a substantially fixed time delay relative to the time base synchronization. The Figure shows an application to a system in which a fast time base gate is automatically locked to a strobe pulse. A synchronizing pulse at terminal 1 cuts off valve V2 to render valve V3 conducting and provide screen grid voltage to the Miller time base valve V4. The negative sawtooth voltage at point 3 is fed to one horizontal deflection plate of indicator K and also back to the control grid of valve V2 to keep it cut off for the duration of the sweep. Valves V13-V19 9 produce a control voltage at point 6, proportional to the timing of the strobe pulse relative to the fast sweep produced in valve V9. When the time base voltage at point 3 falls to the control level, diode V8 conducts and the voltage at point 7 begins to fall in sympathy with point 3 cutting off valve V9, to start a positive fast sweep at point 9 for application to the other horizontal deflection plate of indicator K. Diode V12 stabilizes the positive sweep at 300 volts after about 40 micro-seconds when the resultant time base for the indicator resumes its normal speed. The fast sweep voltage is fed through cathode follower V10 to the suppressor grid of valve V15, and resistors R2, R3 are chosen so that diode V16 stabilizes the potential of the suppressor grid, after one quarter of the fast sweep and prepares valve V15 for conduction. The strobe pulse at terminal 2 then produces a negative pulse a point 13 and the leading edge is differentiated by diode V17, and the capacitor C7. The diode is cut off by the trailing edge of the pulse and the grid of valve V14 is driven positive for the remainder of the sweep. The fast sweep is also differentiated by circuit C5, R4, to remove the negative bias on valve V13 in series with valve V14 so that both valves conduct when the strobe pulse occurs and charge capacitor C6 to a level depending upon the amplitude of pulse at point 13. After the pulse disappears, capacitor C6 is isolated and retains its charge until the next strobe pulse occurs, when valve V14 conducts again to adjust the charge to correspond to the new pulse amplitude. The voltage across capacitor C6 is integrated in valve V19 and applied to diode V7 as the negative control voltage for the start of the fast sweep. If the strobe pulse occurs early relative to the fast sweep, valve V15 is not fully prepared for conduction and the pulse amplitude at point 13 is diminished. The control voltage at point 6 is then less negative, so that the potential at point 7 begins to fall earlier and advance the start of the fast sweep. A late strobe pulse gives rise to a large pulse amplitude at point 13 and delays the start of the fast sweep, which is thus automatically stabilized relative to the strobe pulse.