Time for Two: A Video TDM System That Maintains Spatial and Temporal Resolution for Two Pictures from Different Uplinks

As satellite systems grow, the space segment must be increased. Many have tried to overcome their need for additional transponders by utilizing frequency division multiplexing (FDM) of two video signals on the same transponder. This solution, although technically straightforward, reduces the downlink RF power and significantly modifies the operating parameters of the earth stations involved. Time division multiplexing (TDM), on the other hand, eliminates most of the FDM limitations, but in turn adds new requirements. TDM implies that part of the transmission time will be devoted to each of the signals to be transmitted. The question naturally arises: If less than 100% of the transmission time is provided to each picture, how are temporal or spatial losses to be avoided? The T-4–2 process recognizes the fact that in standard television transmission, each television frame is sent twice. Appropriate preand post-processing of only one frame will provide two complete frames at the receiving point. This article describes a system that also provides synchronous switching between two separated uplinks, while still maintaining spatial and temporal resolution of the picture.

Print ISSN

0036-1682

Published

1990-03

Content type

Original Research

DOI

10.5594/J03925