Wireless Telegraphy and Telephony

WIRELESS TELEGRAPHY 103 spacing in order to be recognizable. American coastwise steamers use the Morse code; transatlantic ships use the Continental code. One of the greatest disadvantages of most systems of wireless telegraphy lies in the fact that no arrangement is provided for simultaneously transmitting" and receiving wireless signals. It is usually necessary for one operator listening to another to have to wait until the finish signal is given before he can reply or interrupt in case he cannot understand part of the message, because the receiving appa- ratus of the transmitting station is necessarily disconnected from the aerial and the ground during the period a mes- sage is being sent. If it were to be connected at this time the powerful currents of the transmitter would rush through the receiving apparatus into the ground without setting up any very powerful waves in the aerial and seri- ously injure the delicate receiving instruments. The Breaking-in-System is a method of simultaneously transmitting and receiving wireless signals. This is accom- plished by providing the transmitting key with a second set of contacts, so arranged that when the key is released between the dots and dashes of the code the aerial and ground are automatically connected to the receiving appa- ratus. When the key is pressed the receptor is automatic- ally cut off. The advantages of such a system are more or less obvious. When interference or a misunderstanding occurs the fact can be immediately signaled to the sending operator, and the message commenced over again.