Patent GB-193438-A (GB)
Title: Improvements in radio-communication and communication by high frequency currents
IPC: H04K1/00
Filed: 1921-08-29
Abstract: 193,438. Wilson, W. H. Aug. 29, 1921. Oscillation generators; keying and modulating systems and apparatus; directive signalling; receiving Systems and apparatus; non-thermionic amplifiers; secret and selective signalling systems; wired wireless systems.-In a method of signalling adapted to reduce interference between stations, a type of radiation is used in which each half wave has a different length from that of the half waves before and after it. Waves of this type may be used in wireless or wired wireless signalling and may be of audible frequency for use in alternating current telegraphy. Such a radiation may be produced by any current containing a capacity which is charged at one rate and discharged at another, and may be received in a similar circuit. For most purposes this circuit takes the form of a branched oscillatory circuit with a rectifier in one or both branches, the frequencies of the common part together with each branch being different. This circuit may be used to generate oscillations and if the branches are similarly tuned provides a heterodyne receiver for ordinary continuous waves. The system may also be used to enable a frame antenna to determine sense as well as direction. In an example Fig. 1 diode valves 5, 6 are included in both branches. A microphone 11 is arranged as shown for transmitting in wireless telephony but may be replaced by a telephone receiver with preferably a small condenser in series on each side of it, or, according to the Provisional Specification, a condenser in parallel. The microphone may be in series with the common part or either branch. In a further example, Fig. 2, the aerial circuit 12 is coupled to a branched circuit comprising rectifiers 15, 16 and batteries 17, 18. The " dichronous " effect is obtained in this case from the fact that for half waves in one direction the effective coupling is with the circuit 13, 15, 17, 19 while it is with the circuit 14, 16, 18, 19 for half waves in the other direction. The telephone 20 may be associated with one or both branches or as shown, and a ticker or the like is provided to make signals audible. In a further example similar to that shown in Fig. 1, a rectifier and battery are provided in one branch only and a telephone in series with a rectifier shunts an inductance in the earth lead. Except where generation of oscillations is desired, batteries in series with the rectifiers are not essential but produce amplification. Electrical dimensions of an experimental set are given in the Specification. In a further example, Fig. 4, a frame 26 determines the sense of received signals. Maximum reception occurs only when each half wave is in such a sense as to produce a current in the branch tuned to it. In a method of generating oscillations, a branched circuit is connected between the antenna and earth. One branch contains ohmic resistance, a Neon tube and a battery, and the other a battery, ohmic resistance and signalling key. In a further example Fig. 6, for signalling along wires by means either of radio or of audio frequency currents, the alternate circuits for the charge and discharge of condenser 37 at the transmitting station are completed by a commutator 42, 43, 44, 45 rotated at a speed such that the brush 45 makes contact for the time of a half oscillation in the branch to which it is connected. The brush 44 has two parts at such a distance apart, or is itself of such a width, that the time of its passage over a conducting segment is equal to that of a half oscillation in its branch. One brush makes contact at the instant the other breaks it. Signalling is effected by a key 40. A similar commutator is driven synchronously at the receiving station. If ultra-audible oscillation are used a ticker or heterodyne source is provided. The batteries 39 at the receiver are optional but may be provided to amplify signals. If they are provided, and if the frequencies used are within the audible range, the telephones are coupled to a balancing circuit comprising branched oscillatory circuits similar in all respects to those shown except that they are not coupled to the line. By this means the sounds which would normally be produced in the absence of signals are balanced out. According to the Provisional Specification the two rectifiers in a circuit such as that shown in Fig 1 are made as a single valve with two plates.