Application to Radio of Wire Transmission 

 Engineering ' 



By LLOYD ESPENSCHIED 



Synopsis: This article points out that radio and wire communication 

 systems are subject, fundamentally, to the same general requirements, 

 and its purpose is to develop for radio, points of view which are familiar 

 to wire transmission engineers. The transmission characteristics over a 

 wide range of distances are compared. For short distances the comparison 

 is favorable to wires. Although over great distances, the attenuation of 

 electric waves, guided by wires, may be greater than the unguided waves 

 of radio, it is pointed out that at the present time intermediate amplifiers 

 can be more economically applied in wire transmission than in radio to 

 boost the message energy. Economy of transmission requires the handling 

 of messages at as low an energy level as possible and, as the author points 

 out, wire transmission satisfies this requirement much better than radio. 

 Referring to the transcontinental line with radio extensions, which was 

 used recently to talk from Catalina Island in the Pacific Ocean to a ship 

 in the Atlantic Ocean, it is stated that had all of the necessary energy been 

 introduced at one end of the circuit, there being no intermediate amplifica- 

 tion, the total power required would have been 1.8 x 10'^ kilowatts, an 

 amount unavailable in the world. In the actual system, distributing 

 the amplification along the transmission line, the power required sums 

 up to something less than 1 kilowatt. 



Interference between messages and extraneous disturbances is discussed, 

 and the requirements involved in keeping message energy well above the 

 energy level of the disturbances in both systems are pointed out. The 

 limitations on two-way operation resulting from "singing" of the entire 

 system are considered for both cases and for combination wire and radio 

 circuits as well. The method of improving the efficiency of transmission 

 by suppressing the carrier and one side band is discussed. Finally the 

 factors involved in obtaining high grade quality of transmission are enumer- 

 ated. — Editor. 



ONE of the most interesting aspects of the development of radio 

 during the last few years, and particularly of radio telephony, 

 is the obvious convergence of its technique with that of wire trans- 

 mission. It is, of course, the advent into both of these arts of that 

 remarkable device, the electron tube, which is responsible for the 

 close technical relations which now exist between them. 



This community of interest, however, altho thus greatly stimu- 

 lated by a device of such range of utility as to find important applica- 

 tions in both arts, is not due primarily to any device per se, but rather 

 to the fact that both type of systems are subject fundamentally, as 

 communication systems, to the same general requirements and design 

 considerations concerning their intelligence-carrying capabilities. 

 These underlying communication requirements lead to similar con- 

 siderations in both types of systems as to the efficiency and fidelity 

 with which the transmission of intelligence is effected and give rise 



• Presented before The Institute of Radio Engineers, New York, January 23, 

 1922. Received by the Editor April 17, 1922, Also printed in the Procd. Radio 

 Institute for October, 1922. 



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