VIRTUAL LAN PRINTING OVER INTERACTIVE CABLE TELEVISION SYSTEM

摘要

A scrambling system for a cable television system in which a group of channel frequencies are reused over a plurality of service areas includes an access controller, an encoder and a plurality of simplified scrambling units. Each service area receives different television signals on the group of channel frequencies. The access controller provides signal authorization information for a given channel frequency to a plurality of receiver/decoders located in the different services areas. The access controller also provides descrambling information corresponding to the signal authorization information to the encoder for the given channel frequency. The encoder produces a conditional access code by placing the descrambling information into a scrambled reference signal. An extracting unit removes the conditional access code from the scrambled reference signal and distributes the conditional access code to each of the simplified scrambling units operating at the given channel frequency. Each simplified scrambling unit scrambles the television signal that is to be delivered to its respective service area and inserts the conditional access code into the scrambled television signal.