An Improved Transmitted Carrier System for Telephone Lines of Short or Medium Length

This paper describes a stackable 1-, 2-, or 3-channel short-to-medium haul telephone carrier system, which has been developed primarily to meet the needs of the independent telephone field. Features of this type number 5 carrier system are transmitted carrier frequencies in harmonic relationship, ringdown signaling by carrier interruption, dial signaling by carrier frequency shift, excellent transmission capabilities, particularly in the second and third channels, and simple installation, testing, and maintenance procedure. Partial suppression of the transmitted carrier frequencies is available, for the occasional application in which the normally higher carrier level on the line might prove objectionable. Through particular attention to the engineering design, the significant objections to transmitted carrier have been overcome, while its greater convenience to the user has been employed to good advantage. The feasibility and desirability of this system have been amply proved by hundreds of successful installations, some of which are on difficult lines where other carrier systems previously failed.