184 BELL SYSTEM TECHNICAL JOURNAL 



It is evidently desirable that the transmitting station shall always 

 put out maximum power whether the speaker has a loud or a weak 

 voice or is near or distant from the transmitting station. One of the 

 duties of the technical operator is to bring this about. By proper 

 indicating meters he knows the power level of the speech going to his 

 transmitting station and he keeps this at the point where it will just 

 completely load the transmitting station. 



Fig. 16 — Fig. 1 with radio connections added 



With this brief discussion then let us assume we have progressed 

 from the conditions of our first illustration to the conditions shown 

 here in which the two great telephone systems are joined together by 

 the radio links. 



To complete the story, a few more words as to the changes and im- 

 provements which development work now under way is expected 

 to give. 



As the system stands to-day it does not offer the privacy which 

 ordinary wire connections offer. While ordinary broadcasting sets 

 are not of the proper type to receive messages from this system, it is 

 comparatively easy, with sets designed for the purpose, to pick up one 

 side of the conversation over the system by listening to the transmitting 

 station in the same country as the listener. Because of the voice- 

 actuated devices, the other side of the conversation has to be picked up 

 directly from the distant country, which is a much more difficult 

 thing to do. 



To give this system a high degree of privacy is difficult, particularly 

 with the long waves. The frequency range in which the long waves 

 are situated is, as already stated, narrow and well filled so that any 

 proposition that widens the required frequency range, such for example 

 as shifting the carrier frequency rapidly, cannot be employed. Methods 

 have been developed, however, and equipment is far iidvanced on a 



