Influence of transmission delay on test conversations in simulated echo-free telephone circuits

The purpose of tests was to find out, whether delay longer than proposed by CCITT might be applied in echo-free telephone circuits, allowing e.g. the use of two stationary satellites in tandem. After shortly reviewing the literature, all main aspects of transmission delay are considered and compared in evaluating the own material. The author points out the influence of transmission delay on the energy and the information level of communication. The impairment proved to be not very grave and did not influence the judgments of the testpersons in general. Thus it is proposed to allow the use of two stationary satellites in one circuit if adaptive echo-cancellers are applied, at reduced taxes. This could be profitable for subscribers and for telephone companies or postal administration likewise.