Abstract: Process for the broadcasting of programmes with progressive conditional access and separation of the information flow, as well as the corresponding receiver,In order to form the elementary flow, groups of m successive elements of the multiplex are taken and for forming the complimentary flow groups of p successive elements of the multiplex are taken.Application to television with entitlement checking.

Abstract: The consequences of the loss of a packet are attenuated in a digital data communication apparatus using packet switching by structuring the digital data as multibit words into frames having a fixed length l and assembling the frames into packets all having the same predetermined length L=kl, where k is a predetermined integer. Continuity index words incremented by one each time a new frame or packet is assembled may be located into the frame locking word or the packet prefix. Then the number of packets which are lost may be determined at the receiver location by monitoring the successively received index words. When the digital data represent successive samples which are correlated, for instance when such samples represent a sound, substitution data may be generated at the receiver location and used in place of the missing data.