Development in Canadian and International Data Above Voice Video (DAV) telecommunications networks

Data Above Voice and Data Above Video (DAV) systems are designed to carry data of the order of 1.544 Mb/s-2.048 Mb/s, in the form of a QPSK subcarrier above the top baseband frequency of existing FDM or TV video channels carried on cable, microwave radio relay, or satellite communications links. As a result of an intensive solely Canadian research and development effort, hardware has been developed and installed on several operating FDM systems. Apart from operating DAV microwave and cable systems in Canada, evaluation testing has taken place in the United States over satellite and terrestrial microwave systems and is taking place in European microwave systems. As a result of the operating experience gained and to achieve even higher levels of performance, new developments were undertaken resulting in the realization of a true diversity DAV system. This system employs a `hitless´ data switch and pseudo-error monitoring techniques. Other new features, all of which are required to ensure optimum performance is achieved, have also been developed. These new developments are described.