An Electron Tube Telemetering System

The paper describes a varying frequency tele-metering system which employs an electron tube beat frequency oscillator, the frequency of which is controlled by a small condenser mounted upon the movement of the instrument, the reading of which is to be transmitted. The reading is reproduced at the receiving end by a frequency meter having a scale corresponding to that of the transmitting meter. The outstanding feature of this system, when furnishing a single indication, is that, except for the movements of the transmitting and receiving instruments themselves, there are no contacts or moving parts. The system does not require instruments of unusual type, and it is not limited to the transmission, only, of electrical readings, but may readily be applied to any deflection instrument indicating, for instance, pressure, temperature, etc. The accuracy of the system is not affected by changes in the impedance of the channel of transmission. The system is equally suitable for transmission over wire conductors or by means of carrier current or radio. A method of furnishing a number of telemetering indications over a single conducting circuit or carrier-current channel, is also described, which uses automatic telephone type selectors at transmitting and receiving stations. A feature of this system is that no synchronizing channel or synchronous power is required. By a system of impulses, the selectors automatically establish and maintain synchronism. A field installation which has given satisfactory results is described.