Telediffusion De France

France Telecom Establissement Autonome De Droit Public

Telediffusion De France S.a.

Alain Gelly

Louis C Guillou

Jean-Luc Giachetti

Roger Charton

The present invention concerns a method of controlling the mode of access to wanted signals, such as picture signals (IMAGE), whereby the user selects an access mode to a wanted signal remotely. A first access mode consists in supplying the user with the original wanted signal (IMAGE), and second access mode consists in transmitting to the user alternately and periodically the wanted signal and a jamming signal (MIRE, IT) into a jammed signal. This jammed signal remains intelligible so that the user can determine the content of the wanted signal and, if necessary, select the first access mode. The two access modes are billed differently. Hardware implementations of the method are described for switching grids of switching nodes in a centralized architecture, and for digital distribution networks with a more futuristic distributed type architecture.

Method and system of controlling the mode of access to signals, in

A process for broadcasting conditional access programs which permits a progressive access. Scrambled program data is transmitted along with partial access checking messages and complete access checking messages such that subscribers having a partial access right may descramble portions of the scrambled data corresponding to information regarding only the identity of the conditional access programs, and subscribers having a complete access right may descramble the remainder of the scrambled data and view the conditional access programs. The conditional access programs may be television pictures, radio programs, or data broadcasts.

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Paris, France

Alain Gelly