INTERAKTIVES HAUSINFORMATIONSSYSTEM

摘要

An interactive cable television system having a plurality of feeder servers, a plurality of home interface controllers and a feeder port. Home interface controllers are each equipped with a radio frequency input and a data communications link with a receiver and transmitter in the feeder port. A node control in communication with the feeder port determines whether a home interface controller is active and then assigns a feeder server to it. The feeder server provides one of a plurality of information signals from a headend depending on a selection input. Digitally compressed video signals are provided at the headend. The digitally compressed video signals can be provided by a modulator means at a carrier frequency greater than the upper frequency limit for carrying analog television signals with acceptable quality on the cable system. The cable television system may make use of a scrambler that maintains the chrome subcarrier on a sync-stripped output signal at all times including the period of vertical retrace. The sync-stripped output signal is modulated at a first carrier frequency and the sync-signal is modulated at a second carrier frequency. A corresponding decoder is provided for receiving scrambled signals and restoring the sync-signal to restore the television signal.