Page:US patent 851336.pdf/2



To all whom it may concern:

Be it known that I,, a subject of the King of Prussia, residing at Berlin, Germany, have invented certain new and useful Improvements in Transmitters, for Wireless Telegraphy, of which the following is a full, clear, and exact description.

In practical exchange of messages between wireless telegraph stations the problem frequently exists of tuning the transmitter of one station to the length of the waves of a distant transmitter, either for the purpose of answering the distant station or, what is for military purposes of greater importance, with the object of preventing the receipt of messages between other stations communicating with one another. In the latter case great speed in the tuning of the transmitter to the distant emitted wave is of the greatest importance, in order that the foreign stations may not find time to deliver an understandable message.

In transmitter arrangements hitherto known, the method pursued was to tune the receiving aerial conductor first by means of a detector which responded to variations of amplitude of the waves, and to ascertain the wave lengths of the foreign transmitter from the hereby resulting dimensions of the self-induction coils and condenser; then the transmitter of the home station was tuned to the same wave lengths with the assistance of an ordinary wave meter. For this a double tuning is thus necessary, firstly that of the home receiver and then that of the home transmitter, and this method necessitated a great waste of time.

Now this invention relates to an arrangement of transmitter in which one manipulation is omitted, and the home transmitter is directly tuned by means of a detector connected therewith. The transmitter may then be immediately used for dispatching the ascertained wave, after this detector has been switched off.

In the present invention it is of importance that no deleterious or impeding alteration of the length of the waves of the transmitter shall take place by the switching off of the detector from the transmitter.

This improved arrangement of transmitter will now be more particularly described with reference to the accompanying drawings, in which:

is a diagrammatic view of the new arrangement in combination with a simple transmitter in which the sparking device is arranged directly in the aerial wire. Figs. and are modifications of ; and  shows the use of the invention in a transmitter which is fed from a closed exciter circuit.

In, 1 is the aerial conductor from which a wire 2 leads to the receiver apparatus which is switched off by means of a switch when transmitting from the home station. 3 is the sparking device which is composed of several small spark gaps to each of which a small condenser is inserted in parallel with the object of uniformly distributing the charge potential over the separate spark gaps. 4 and 5 indicate a variable condenser and a variable self-induction for altering the length of the waves of the transmitter. 6 is an earth connection or a wire which connects the aerial conductor to earth or an equivalent electrical counterpoise: 7 is a switch by means of which the detector 8 may be switched into the transmitter circuit. This detector is of such a kind that it enables alterations of amplitude of the electric waves transmitted to it, to be ascertained, that is to say a so-called integral detector. In the present case an electrolytic cell is employed for this object, over which cell the current of a battery 9 constantly flows, which is connected with the detector by means of choking coils 10. A telephone 11 also lies in the local circuit by means of which telephone all alterations in the electric behaviour of the cell may be ascertained. A comparatively large condenser 12 variable in its capacity, lies in parallel with the cell.

With the object of tuning the transmitter to the length of the waves radiated from a distant transmitter the procedure is as follows: The sparking device is first short circuited by means of the switch 13, and then by means of the switch 7 the cell 8 is switched on into the transmitter circuit with the condenser 12 lying parallel with the cell. The condenser 12 is then adjusted to an average capacity and the condenser 4 and the self-induction 5 altered until the maximum pitch or strength of sound is obtained in the telephone 11. The capacity of the condenser is then enlarged and now the condenser 4 and self-induction 5 are suitably altered until again the greatest strength of sound in the telephone takes place. The operation is continued in this manner under constant en