Importance

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Abstract

A bi-directional data transmission and control system utilizing a central processing unit and a multiplicity of remote subscribers. Each subscriber is provided with a terminal coupled with the central processing unit by a suitable medium such as a CATV channel. Each terminal is provided with a demarcation plane separating common circuitry from a number of specialty modules and a common bus therebetween for circuitry simplification, application expandability and individual tailoring. The data transmission scheme efficiently utilizes the frequency spectrum and enhances polling frequency by permitting selective polling of any given specialty module or subscriber at any given time and by permitting simultaneous polling of every subscriber for service calls, thereafter locating the caller with minimal polling. Data transmission protocol is expandable or contractable for each terminal independently of others and permits data transmission between any two points in the system. The system is zoned such that failure of one zone does not disable the entire system.

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First Claim