Multiple radio-telephony and radio-telegraphy

摘要

387,114. Multiplex and duplex wire- 'less signalling. LOTH, W. A., 20, Avenue KlÚber, and GIVELET, A. J., 24, Rue Bois le Vent, both in Paris. Jan. 22, 1932, No. 2055. Convention date, Jan. 23, 1931. [Class 40 (v).] A system of multiplex radio signalling comprises two valve oscillators at a transmitting station, and two valve receivers at a receiving station, all with their plates or grids polarized from centre-tapped transformers or like potential-dividing devices supplied with synchronized supersonic alternating current. At any moment one oscillator and one receiver are active, the others inactive. Fig. 1 shows a transmitting station with the plates of the oscillator valves L, L1 supplied from the synchronized source through a centre-tapped transformer T. Modulation is applied to the respective valves by microphones or other signal sources in the leads A, B. The valves L, L1 are active alternately, and at the receiving station the valves are similarly arranged, being brought into action alternately at synchronous speed by applying the supersonic synchronizing wave to their plates or grids. For duplex working, one valve at each station may be a transmitting valve, the other a receiving valve. Each oscillator L, L1 may comprise a pair of valves connected in push-pull, with the polarizing voltages from T applied at the middlepoints of the plate coils. Specifications 250,747 and 289,102, [both in Class 40 (v), Wireless signalling, &c.], are referred to. The Specification as open to inspection under Sect. 91 describes also a system of multiplex signalling in which a single short carrier wave is modulated by a number of different long waves each carrying its own signal modulation. The signals are separated at the receiver by tuned selective circuits after the first detecting stages. For secrecy, a single signal may be switched in sequence from one channel to another by means of cams or the like. A further system shown in Fig. 1 (Cancelled) comprises a stator 1 with the windings of alternate poles connected in series in two separate circuits, each including a microphone A, B. The rotor arm 2 carries a single winding 3 terminating at slip rings with brushes connected to a radio transmitter 6. The two microphone circuits thus act alternately at supersonic frequency on the transmitter; and a similar device splits up the detected signal at the receiver. The rotor coil may be connected in opposition with a second rotor coil rotating at equal speed between polepieces wound with coils to which no signal current is supplied. In a further modification, modulated carrier currents are supplied to the stator, which acts on the rotor by electrostatic induction. This subject-matter does not appear in the Specification as accepted.