초록 ▼

A two-way CATV system having a substantial number of terminals incorporates a central processor and transmitter system which continually interrogates the terminals at high speed, monitoring changes of usage of premium programs and other data while also permitting central control of access to restric

A two-way CATV system having a substantial number of terminals incorporates a central processor and transmitter system which continually interrogates the terminals at high speed, monitoring changes of usage of premium programs and other data while also permitting central control of access to restricted premium programs. For inexpensive but reliable intercommunication, short, fixed word length digital messages are frequency multiplexed onto the cable in both upstream and downstream directions, and subscriber groups are controllably selected in turn, with each subscriber being scanned in what may be an arbitrary order by transmission of unique private messages which are recognized at the terminal and in response to which previously prepared fixed length messages are immediately transmitted in return. By employing both upstream and downstream messages which are initiated by a series of synchronizing bits and non-ambiguously related subsequent data sequences, and by the provision of means to initiate both downstream and upstream messages of short length without delay, rapid but reliable data interchange is effected despite differences in transmission and response times with different subscribers. Concurrently, terminal status and various special conditions including security alarms are remotely processed at each terminal, and short upstream messages are assembled containing priority selected data to be transmitted in response to an interrogation. The system incorporates additional means for monitoring power status, program selection and authorization and other operating conditions at each terminal effectively to provide accurate and reliable accounting information while preventing unauthorized or improper usage of restricted premium programs.

대표청구항 ▼

In a CATV system having a plurality of subscribers, a system for addressing any selected individual subscriber on an asynchronous basis with a sufficiently short message such that all subscribers can be addressed within a relatively short time interval, the combination comprising: a transmission net

In a CATV system having a plurality of subscribers, a system for addressing any selected individual subscriber on an asynchronous basis with a sufficiently short message such that all subscribers can be addressed within a relatively short time interval, the combination comprising: a transmission network including a main trunk, branch amplifiers coupling the main trunk to a plurality of branches and distribution means coupling each of the branches to an individual subscriber\s location, the branches being arranged in groups; transmitting means for concurrently transmitting video programs and data messages in different parts of the frequency spectrum on said network; coding means coupled to said transmitting means for encoding messages for said individual subscribers, said messages comprising sync, group address, private address and command data, the sync data comprising a selected sequence of binary-valued representations of one value, the data patterns being bisected by a binary-valued signal of the opposite value to the sync data value into bit sequence lengths that are shorter than the length of the sync bit sequence; and means disposed at the subscriber terminals for responding to the appropriate private address.