An Improved High-Frequency Radiotelephone System Featuring Constant Net Loss Operation

Abstract

A system is described in which a special type of syllabic compandor and other features offer an improved solution to the problems of using HF radio facilities for overseas telephone trunks. A major disadvantage of existing systems is the use of voice‐operated gates to prevent singing and echo effects. These gates interfere with the free flow of conversation. The new system allows stable full‐duplex operation as in conventional telephone circuits because a nearly constant circuit loss is maintained between the trunk terminals. Significant improvements in circuit quality result from full‐duplex operation and from a reduction in the effects of radio noise and interference by compandor action. Preliminary results of a field trial between New York and Buenos Aires have been highly favorable.