L5 System: Transmission Networks and Magnetic Components

Transmission Networks and Magnetic Components By J. L. GARRISON, A. OLSEN, JR., and T. H. SIMMONDS, JR. (Manuscript received March 4, 1974) The development of transmission networks and magnetic components for the L5 system represents the largest network development project of its type ever undertaken within the Bell System. Over 200 different coded designs of networks, requiring in excess of 1+0 man-years of effort, were required to meet the frequency-selective and signal-shaping requirements of the system. Despite this effort, neither systems requirements nor systems schedules could have been met without significant contributions from allied technologies. This article identifies those technologies and describes design techniques that have advanced the state-of-the-art capabilities in transmission network and magnetic component design. I. TRANSMISSION NETWORKS 1.1 Introduction As in other analog systems, transmission networks of the L5 CoaxialCarrier Transmission System perform the indispensable functions of frequency selection and signal shaping. Without the filtering functions provided by certain of these networks, the basic multiplexing arrangements on which the system depends could not be realized, nor could the various fault-locating, equalizing, regulating, and switching pilots be effectively separated from the message portion of the line signal. Similarly, without use of the wide variety of equalizers provided, the amplitude distortions introduced as the signal traverses the line could not be as effectively corrected.