3J2 BELL SYSTEM TECIIXICAL JOURNAL 



the voltage curve, will be less. A cursory examination of the litera- 

 ture does not disclose that anything has been published on the experi- 

 mental side either to confirm or to oppose this result. 



Choke of Codes 



A formula will fust be derixcd b>' means of which the speed of trans- 

 mitting intelligence, using codes employing different numbers of 

 current values, can lie compared for a gi\en line speed, i.e., rate of 

 sending of signal elements. Using this formula, it will then be shown 

 that if the line speed can be kept constant and the number of current 

 values increased, the rate of transmission of iiiulligence can be ma- 

 terially increased. 



Comparison will then be made between the theoretical possibilities 

 indicated by the formula and the results obtained by various codes in 

 common use, including the Continental and American Morse codes as 

 applied to land lines, radio and carrier circuits, and the Continental 

 Morse code as applied to submarine cables. It will be shown that the 

 Continental and American Morse codes applied to circuits using 

 two current values are materially slower than the code which it is 

 theoretically possible to obtain because of the fact that these codes 

 are arranged so as to be readily deciphered by the ear. On the other 

 hand, the Continental Morse code, as applied to submarine cables, 

 or other circuits where three current values are employed, will be 

 shown to produce results substantially on par with the ideal. Taking 

 the above factors into account, it will be shown thai if a given tele- 

 graph circuit using Continental Morse code with two current \alues 

 were rearranged so as to make possible the use of a code empkning 

 three current values, it would be possible to transmit over the re- 

 arranged circuit about 2.2 times as much intelligence with a gi\en 

 ninnber of signal elements. 



It will then be pointed out why it is not feasible on all telegraph 

 circuits to replace the codes employing two current values with others 

 employing more than two current values, so as to increase the rale 

 of transmitting intelligence. The circuits, for which the possibilities 

 of thus securing increases in speed appear greatest, are jiointed out, 

 as well as those for which the possibilities appear least. 



TlIEOKKTICAL POSSIHII-ITIES UsiXG Coi>ES \VHII Dll IKRENT 



NuMKERs OF Current V'.m.ies 



The speed at which intelligence can be transmitted over a telegraph 

 circuit with a gi\en line speed, i.e., a gi\en rate of sending of signal 



