Telediffusion De France

Etablissement Public De Diffusion Dit 'telediffusion De France'

Centre National D'etudes Des Telecommunications

Etat Francais Represente Par Le Secretaire D'etat Aux Postes Et

Michel Alard

Daniel Pommier

A digital broadcasting process, suitable for digital audiobroadcast, comprises encoding the data in the form of binary words using a redundant code to obtain a sequence of modulation symbols and transmitting the symbols in a plurality of subchannels at different frequencies. The symbols are time interlaced with such a distribution that two adjacent symbols cannot be transmitted in time succession and at the same one of the frequencies. Preferably, a Viterbi decoder is used. Particular construction of an emitter and a receiver are also described.

Method and installation for digital communication, particularly between

In a broadcasting system with time division multiplexing of digital signals containing a synchronization pattern and analog signals, sync extraction is achieved with a process including detecting the extreme values of the signals to be subjected to decoding, after they have been amplified with a gain G, with a time constant compatible with the low cut off frequencies to be accomodated; the gain G is controlled as a decreasing function of the difference between the extreme values with a time constant greater by several orders of size than the repetition period of the multiplex; before decoding and determination of the extreme values, there is added to the amplified signal a DC component which is a decreasing function of the sum of the extreme values, until the retrieval of the clock signal and identification of the synchronization pattern downstream of the coding.

Growing community of inventors

Rennes, France

Michel Alard