In 1983, Viacom successfully implemented a value-added data communications service for the City of Mt. View, CA Police Department. Asynchronous terminals were remotely linked to a host CPU for interactive file inquiries and updating. Sytek packet-switching broadband moderns linked the terminals to the host over a subsplit institutional cable.
The subsequent success of the application proved that a subsplit system could be used for a value-added CATV communications service. In order to be economically viable, however, the service must cover a wider geographical area than the small subsplit institutional cable system in Mt. View. Since the service should potentially cover a wide metropolitan area, then it must be interfaceable to entertainment and institutional cable systems, two-way microwave links, and private broadband local area networks.
Viacom's Nashville CATV system is a subsplit, 1800-mile entertainment cable with AML microwave linking 6 hubs and 200 to 300 miles of plant to a master Headend. The service area has large geopolitical boundaries (an entire city and county) , and therefore enough potential users to justify implementation of a two-way enhanced service.
This paper describes the implementation of this packetized broadband data communications service over a hybrid microwave and CATV system covering a large metropolitan area.