GB595285A - Ultra high frequency communication systems - Google Patents

Abstract

595,285. Pulse modulation. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 16, 1945, No. 12365. Convention date, April 22, 1942. [Class 40 (v)] A pulse radio communication system utilizes a blocking oscillator as the carrier source, the timing of the pulses being varied by applying the signal voltage to vary the resistance of a leak path for the grid condenser. The oscillator may comprise a push-pull valve pair 1, 2 with resonant Lines as their anode, grid and cathode circuits. The grid condenser 12 is connected between the tuning-sliders 8, 11 of the grid and cathode circuits and the leak path comprises a triode valve 13 with its anode connected to the positive terminal B + of the high-tension source. The signal is applied to the grid of the valve 13 through a transformer 14. With no signal, the oscillator gives regular pulses of carrier energy, the spacing of which is determined by the leak path for the condenser 12. As the resistance of this path is varied by the signal, the spacing of the carrier pulses is correspondingly varied. The anode potential of the oscillator may be of high value, and the power developed during pulse emission may be much greater than the continuous power rating of the valves. The receiver may be provided with automatic gain control which may bias off all but the pulse peaks so as to eliminate noise.