The L3 Coaxial System 



Equalization and Regulation 



By R. W. KETCHLEDGE and T. R. FINCH 



(Manuscript received April 17, 1953) 



The equalization and regulation problems of the L3 system are described 

 and a theory of equalization of complex systems is outlined. The location 

 and function of the various equalizers are explained including the roles 

 and design of the various fixed, dynamic and manual equalizer networks. 

 The analog computer used in the regulation system is described together 

 with the cosine-equMizer adjusting technique used with manual equalizers. 

 Finally the circuits and operation of the regulation system and its com- 

 ponents are presented. 



Introduction 



Equalization is the process of correcting system gain and delay devia- 

 tions sufficiently to permit the satisfactory transmission of signals. 

 Regulation refers to that part of equalization which, by automatic 

 means, corrects for relatively rapid changes in transmission. In the L3 

 coaxial system the transmission of television signals through more than 

 1,000 ampUfiers introduces relatively severe equaUzation and regulation 

 problems. Compared to the LI system, the L3 system has nearly three 

 times the band\\ddth and over three times more stringent transmission 

 objectives. Thus it has been necessary to devote considerable effort 

 towards finding equalization methods that yield practical and economical 

 solutions. 



In previous systems it has often been the practice to design the bulk 

 of the equalization system after the completion of an initial installation 

 and the determination of the deviation characteristics of the system. 

 In order to expedite the introduction of the L3 system into the field, 

 equalization study and planning were initiated at the very beginning of 

 the development of the system. One of the design methods was to make 

 highly detailed studies using relatively inadequate data in order to find 

 the major problems. As the data improved the studies were likewise 



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