Telediffusion De France

Etablissement Public De Diffusion Dit 'telediffusion De France'

Alain Komly

Patrice Bourcet

Alain Weisser

Alain Viallevieille

Michel Maillard

Michel Seguin

A synchronized broadcast network comprises a main transmitter transmitting an audio source signal to a plurality of receiver/transmitter units remote from each other and from the main transmitter, the receiver/transmitter units broadcasting the audio signal using frequency modulation. In the main transmitter the audio source signal is digitized by sampling it at a predetermined sampling frequency. A digitized signal representing the sampled audio signal is transmitted to the receiver/transmitter units. In each receiver/transmitter unit a reference signal representing the sampling frequency is derived from the received digitized signal and the received digitized signal is passed through a succession of digital processing stages including a stage in which a carrier derived from the reference signal is digitally modulated and a stage in which the result of the digital modulation is digital-to-analog converted. In one of the digital processing stages the received digitized signal is delayed for a predetermined time in order to synchronize the phase of the receiver/transmitter units. All the digital processing stages are synchronized to the reference signal to obtain identical digital modulation of the same carrier for all the receiver/transmitter units. The result of the digital-to-analog conversion stage is transposed to a final frequency derived from the reference signal for broadcasting the analog audio signal using frequency modulation with the same modulation, phase and carrier at all receiver/transmitter units.

Frequency modulation broadcast transmitter synchronization method

The invention relates to a process for the transmission in blocks of digital information words with a correction capability. This process consists of transmitting in blocks digital information words, each information word having a length of n.sub.1 bits, in which with each sequence of n.sub.2 -k (n.sub.2 &gt;k) of consecutive information words are associated k redundancy words of n.sub.1 bits each in which, for each order i (1&lt;i&lt;n.sub.2), the k bits of order i of the redundancy words are redundancy bits in accordance with a Hamming code (n.sub.2 0k, k). For each set of n.sub.2 linked words, each word is transmitted while being protected by an error detecting code. Several sets of linked words can be interlaced. The words of the same order or rank of each set form a group and the groups can be formed by frames.

Process for the transmission in blocks of digital information words with

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Paris, France

Alain Komly