178 



BELL SYSTEM TECHNICAL JOURNAL 



are not especially representative of what can be done with a system 

 after it has begun smoothly in commercial service, but are inter- 

 esting in giving a general idea of the way the system worked and in 

 showing that calls were successfully put thru in a reasonably short 

 time. In the aggregate a large number of calls were made, and as a 

 result the system was put to a fairly severe operating test. It was 

 found, as was to be expected, that the time required to put thru the 



=m 



Net. 



-1 



=g| 



THREE CHANNEL OPERATION 



:Q= 



=CF 



Hybrid Coil 'channel 2 



Hybrid Coil Channel 3 





Calling 

 Channel 



=nr f=h 



Fig. 23 



„ f I Transmitting Frequencies 



'3 I r>f Qhnr* <^tar inns 



of Shore Stations 



e Calling Frequency 

 ' of BoOi Stations 



radio connections to the vessels is large in comparison with the con- 

 necting time on the wire lines, and will require that precaution to be 

 taken in the operating routine to minimize the time during which wire 

 circuits are held up pending connection with the radio link. (The 

 wire circuits used in the tests appeared in New York on a busy P.B.X. 

 (private branch exchange) and did not receive the operating attention 

 that they would in regular service.) But even tho the radio holding 

 time was larger than the usual wire time, it is in itself rather surpris- 

 ingly good considering the difficulties which attended this maiden 



