Etablissement Public De Diffusion Dit 'telediffusion De France'

Telediffusion De France S.a.

Etat Francais Represente Par Le Ministere Des Postes, Des

L'etat Francais, Represente Par Le Secre-d-etat Aux Postes Et

La Telediffusion Centre National

Joseph Blineau

Louis C Guillou

Yves M Noirel

Daniel Pommier

Jean-Pierre Bauduin

Francoise Coutrot

Claude Thomas

Vincent Lenoir

Pierre Leray

According to the invention, the control messages are constituted by a general addressing message (GCM), followed by shared addressing messages (SACM). The message (GCM) contains all the information common to all the user groups and a confirmation data item of the group of users and the messages (SACM) a shared address. Thus, the group is defined in a manner inherent in the control messages and can undergo reconfiguration at any time. Application to more particularly satellite broadcasting of television programmes.

Process for the broadcasting and reception of access title control

A digital data pack transmission system is especially--but not exclusiveluseful in videotex or teletext transmission (i.e. videotext or teletext data is transmitted during intervals between segments of video signals). The inventive system uses a continuous transmission carrier. A plurality of data packs are individually included in each block of data which is periodically transmitted. Dummy packs are used to fill the blocks, if less than a full complement of packs is required. The time periods available for the transmission of blocks of data are exactly equal to or a little longer than the maximum length of the transmitted blocks. The beginning of each data block has a synchronization bit pattern which is constituted by a 'bit sync' byte followed by a 'byte sync' byte. Except for the synchronizing pattern, the signals are scrambled before transmission and descrambled upon receipt and recognization of the data.

Multiplex channels for continuous flow for numerical signal

This test equipment permits a testing of the demodulator of a teletex television receiver. It consists of a digital test signal generator, the output of which is connected to the HF input of the television, and a receiver, the input of which is connected to the video output of said receiver. The generator tramsmits pseudo-random data packets having a first frequency of binary elements, with two double-intervaled binary elements at two predetermined instants t.sub.1 and t.sub.2 for each packet. The receiver has a data regeneration circuit whose threshold varies line by line from a maximum value to a minimum value. The sampling clock of the receiver is at a second frequency lower than the first by the ratio (n-2)/n, where n is equal to the integral ratio of the first frequency to the line frequency of the television. A suitable means insures resynchronization of the sampling clock at the middle of each line. A receiving circuit for the pseudo-random data detects the errors which are transmitted to the video input of the television.

Test equipment for a teletex television receiver

Growing community of inventors

Rennes, France

Joseph Blineau