Etablissement Public De Diffusion Dit 'telediffusion De France'

L'etat Francais, Represente Par Le Secretaire D'etat Aux Postes Et

National D'etudes and Etablissement Publie De Diffusion Dit

Etat Francais, Represente Par Le Secretariat D'etat Aux Post Es Et

Daniel Pommier

Joseph Blineau

Jacques Veillard

Claude Thomas

Jeannine Le Goff Epouse Henaff

Digital broadcasting of a sound program takes place in a channel of a set of channels. In each channel other than that dedicated to digital broadcasting, the television channel has a spectrum of spectral lines separated by low spectral power density intervals. Digital broadcast is achieved by digital modulation (for instance OFDM) of the transmission with frequency multiplexing using a spectrum interlaced with that of the television. The digital signal is recovered by comb filtering on reception.

Method of digital sound broadcasting in television channels with

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

The circuit comprises a surface acoustic wave device. On the substrate (32) f the surface acoustic wave device, are provided two pairs of input transducers (33, 34, 35, 36) connected, in parallel, to the input of the circuit. The transducers (33, 34, 35, 36) initiate surface acoustic waves corresponding to the signals applied on two pairs of paths (41, 42, 43, 44) ending at two pairs of reception transducers (37, 38, 39, 40). The outputs of the output transducers of the first pair (37, 38) are connected to the two inputs of a mixer (28) whose output yields the received digital signal. The outputs of the second pair of transducers (39, 40) are connected to the inputs of two limiters (26, 27) whose outputs are connected to the two inputs of a mixer (29) whose output yields the analog signal. The difference in path lengths of the first pair (41, 42) introduces a delay of the order of one bit and the difference in path lengths of the second pair (43, 44) introduces a delay equal to the inverse of twice the bandwidth between the peaks of the discriminator thus constituted.

Reception circuit for a wave modulated at one time in frequency by an

To obtain a duo-binary FSK modulation, the modulating binary signal train has a three state partial response and is fed through a precoding, a transition-type coding, a simplified MSK modulation at the carrier frequency, a frequency division by two, and a multiplication by the same signal delayed by one binary element period. In order to obtain a 'tamed FSK' modulation, the modulating binary signal train has a five state partial response and is fed through precoding, a transition-type coding, a simplified MSK modulation at the carrier frequency, a frequency division by two, a multiplication by the same signal delayed, for one part, by one binary element period and, for the other part, by two binary element periods. A TFM modulation is obtained by using the FSK duo-binary generating process, but a wave shaping filter is connected between the division by two circuit and the multiplication circuit. In a TFM modulator, the train of binary signals is applied to a partial response precoding circuit, the output of which is connected to a transition-type coding circuit, the output of which is connected to the input of a simplified MSK modulator, the output of which is connected to the input of a frequency divider by two, the output of which is connected to the input of a wave shaping filter, the output of which is directly connected to an input of a multiplier, and to the other input of the multiplier via a delay-type circuit.

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Mordelles, France

Daniel Pommier