Public communication system comprising distributed stations, and station and sub-station for use in such a communication system

Abstract From the Canadian patent

A public communication system for encrypted audio/video information has various selective entitlement organizations with respect to its distributed receiver station. Such receiver station comprises one or more receiver sub-stations for decrypting the received encrypted information by means of a decrypting key. Furthermore the receiver, station comprises one or more decription key sub-stations that may be interrogated by the receiver sub-stations and thereupon may verify a conditional access requirement, and in case of positive verification forward decryption key information to the interogating receiver sub-station. All said sub-stations axe interconnected by a serial standard bus, so that …