Coaxial cable system for 2700 circuits

Work was conducted on the possible use of transistors in a 12-muH 2700-circuit transmission system on coaxial cable of 2.6/9.5 mm. The line amplifier, the "heart of the system", is considered in detail. Its desirable properties are listed, and the authors provide an adequate description of the circuit configuration and give performance details on noise, overload, and harmonic and inter-modulation margins. Attention is also given to optimum repeater spacing, the establishment by computer of the optimum pre-emphasis characteristic for the system, automatic level regulation, and fault location. Finally a detailed description is given of a trial system, installed with the co-operation of the G.P.O. on part of the co-axial route between Guildford and Reading. The authors conclude that the measurements obtained show that the design aims have been met and that the relevant recommendations of CCITT and G.P.O. specifications are satisfied with adequate working margins. It is further claimed that the new system is economic.