Abstract: A device for allowing fee paying subscribers access to television or radio programs includes a keyboard unit for requesting messages concerning the programs. Information describing the program fees and account status is contained in a subscriber held security processor such as a smart card. As a function of the content of the requests a mechanism converts the information contained in the security processor into intelligible messages as a function of complementary information transmitted regularly within television and/or radio signals.

Abstract: The process concerns the plotting of overextending curves inside a limited display window, with cutting-off of the parts of the curve which extend beyond the imposed display window. The goal is to provide a process for the plotting of overextending curves inside a display window, which optimizes calculation time and plotting time. This goal is achieved by means of a process characterized in that it manages a first process for plotting, applicable to the portions of curves (55) inscribed inside the window, and a second distinct process for processing of the overextending parts (54) of the curve, in that the processing of the overextending parts consists in optimizing travel (51, 52, 53) along the projection of the overextending parts on the window border (X.sub.max, Y.sub.max), and in that the said processing process is entirely executed within the plotting process, and in the course of the plotting of the curve.

Abstract: A digital data transmission system comprises at its input a higher order multiplexer receiving at least one stream of digitized data organized into blocks and at a specific timing, said multiplexer transmitting each block of data in a digital multiplex to the output of the transmission system via a digitized data transmission channel subject to a variable multiplexing delay. To reduce the low-frequency component of the jitter in a timing signal reconstituted at the output of the system, the multiplexing delay is measured for the current transmission of a block of data in the multiplex and the measured multiplexing delay is compared with a reference value to determine a multiplexing delay offset and if necessary to defer said current transmission. The measurement and comparison are repeated for the next transmission of a block of data in the multiplex using in the comparison the multiplexing offsets determined for previous transmissions.

Abstract: A method for the broadcasting of digital data, in channels to which multiple paths are assigned, the characteristics of which vary in time, with time-frequency interlacing and assistance in the acquisition of the automatic frequency control. This method is one of the type providing for the distribution of the data in the form of digital elements in the frequency-time space f-t and the transmission of frames of symbols each constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of the digital elements and broadcast simultaneously, the method providing for the transmission of a pattern of frequency synchronization, recurrent in time. It can be applied notably for radio broadcasting at a high bit rate towards mobile receivers, and for example, to COFDM radio broadcasting.

Abstract: In a multichannel encoding method for encoding digitized pictures, in particular digitized stereoscopic television pictures, the digitized pictures are processed in different channels comprising at least a movement estimation channel to provide digitized picture encoding data. A particular processing channel is chosen on the basis of this encoding data. In the movement estimation channel an input digitized picture is divided into blocks of pixels to provide a movement vector for each block and an error for each block pixel. For each block, a set of values is calculated relative to a block mean error, a block error standard deviation, a block error mean deviation and an amplitude of the block movement vector to choose the particular processing channel assigned to said block on the basis of the set of values.

Abstract: The generator of the invention includes an initialization circuit (CI) delivering four initialization words (QI, RI, SI, TI), one calculation circuit (CC) composed of four sub-units (SQ, SR, SS, ST) corresponding to four generating polynomials of orders 5, 5, 7 and 7, and finally one output logic circuit (CS) delivering a pseudo-random byte sequence.Application for systems with access control, especially television systems.

Abstract: 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.

Abstract: A method and device are disclosed for scrambling-unscrambling digital image data. The data is subjected to processing for extracting the colorimetric components of the pixels forming the image, the components being formed into blocks b(I,J) of N.times.N pixels x(i,j) so as to generate corresponding spatial chopping of the image where I designates a line index and J a column index of arrangement of the blocks in the image, i and j designating a line index and a column index of arrangement of the pixels in each block. The pixels and/or blocks are subjected to an intra-block and/or inter-block mixing procedure. The inter-block mixing consists of an arbitrary re-arrangement of said blocks of pixels and the intra-block mixing mixing consists of an arbitrary re-arrangement of the pixels os each block so as to obtain a scrambled arrangement of blocks and/or pixels.

Abstract: A device for the transmission of digital data with at least two levels of protection, of the type providing for the distribution of the data to be transmitted in the form of digital elements in the time-frequency space and the transmission of symbols each formed by a multiplex of N orthogonal carriers modulated by a set of the digital elements, and transmitted simultaneously, the device including channel encoding means comprising at least two types of modulation and/or at least two encoding efficiency levels. This enables to optimize the use of the transmission channel by assigning differentiated transmission techniques to portions of data of a same digital train as a function of the different levels of protection sought, against transmission errors.

Abstract: An encoding and transmission method with at least two levels of quality of digital pictures, each digital picture being formed by at least one matrix of encoded picture elements, wherein each of the pictures is cut up into blocks of picture elements, a reversible mathematical transformation is applied to each of the blocks of picture elements, the coefficients of the transformed picture blocks are quantized and the quantized coefficients are encoded. The transformed coefficients are divided into at least two digital trains, the first train including basic coefficients enabling the reconstruction of a standard quality picture, and at least one second digital train including a set of complementary coefficients enabling the reconstruction of higher quality pictures, in combination with the basic coefficients of the first digital train and possibly the coefficients of other complementary digital trains, the digital trains being processed and/or used distinctly, during the encoding.

Abstract: A method for the diffusion of digital data designed to be received notably by mobile receivers moving in an urban environment, that is, in the presence of stray signals and jamming, and in conditions of multiple propagation (Rayleigh process) providing an optimized mode of setting up the frame structure of the broadcast signal, so as to derive the maximum benefit from the resistance of the system to pulsed stray signals and to jamming. The header of each frame has a first empty synchronization symbol and eventually a second, unmodulated wobbled signal forming a two-stage analog synchronization system. So, the recovery of synchronization is achieved in an analog way, without prior extraction of a clock signal at the binary level. The constitution of the sequence of the useful symbols in the frame results from temporal and sequential interlacing operations, combined to obtain an implicit de-interlacing at the receiver.

Abstract: Disclosed is a method to achieve a sub-sampling of pictures, making it possible to optimize the spatial and temporal definition of the compressed signal, so as to enable a most faithful possible reconstruction of the picture received with said compressed picture signal and, if necessary, with complementary assistance data. A field of speed vectors is defined for at least each picture to be sub-sampled, and said pictures to be sub-sampled are sub-sampled by eliminating certain picture points, the preserved picture points being chosen so as to avoid selecting a picture point which corresponds spatially to the approximate projection of a source point preserved during the sub-sampling of the preceding sub-sampling picture, said projection resulting from the application, to said source point, of the associated shift vector.

Abstract: The field of the invention is that of data processing modules placed in a receiver of a data transmission or emission network, and charged with the equalizing and time-pulse recovery of the received data, in order to furnish to the next elements of the chain of the receiver a clear signal with a clean and resynchronized clock phase.The objective is to provide a device extending the limits of restoring the service in the case of strong disturbances of the channel.

Abstract: An audio signal is multiplexed into a video picture signal by converting the audio signal into a sequence of digital code words from which subwords are extracted relative to a video signal line frequency. The number of bits in each subword is determined as a function of the amplitude dynamic range of the video signal, and each extracted digital subword is converted to provide analog samples with amplitudes proportional to quantizing of the corresponding digital subword. These analog samples are used to amplitude modulate an active portion of the video signal corresponding to a picture so as to provide a "composite" signal having the format of the video signal.

Abstract: The stereoscopic convergence is adjusted in stereoscopic imaging equipment to increase or decrease the stereoscopic convergence angle. Two imaging devices are disposed symmetrically relative to a median optical axis to generate video signals representing images of an observed scene. Depending on the required stereoscopic convergence angle, two image "read windows" are positioned symmetrically relative to the median optical axis, each being defined by a first pixel and a last pixel of a processed image line. The first and last pixels of a processed line are disposed between the first and last pixels of a raw (oversize) image line, with the result that the video signals generated by the stereoscopic imaging equipment represent righthand and lefthand processed images in corresponding relationship to the raw image read windows.

Abstract: A transmission line formed by a twisted pair of conductors with at least one input point for connection to a device for injection of a signal into the pair of conductors, and several output points for connection to devices for tapping of the signal transmitted on the pair of conductors. Each of the points has means for symmetrical tapping of the signal on the two wires of the pair. The tapping means has a high impedance with respect to the impedance of the pair of conductors, and is compatible with a multiple tapping of the signal on the pair of conductors. This transmission line permits the transmission of signals emitted in wideband, such as baseband video signals over distances of several hundreds of meters, with multiple tapping of a signal on one and the same line of the network, without causing any mismatching phenomena.

Abstract: A filtering cell including a resonant circuit having an inductor and capacitor connected in parallel, the inductor being separated into two identical inductors which are connected in series with a midpoint therebetween. A second capacitor is connected at the midpoint and has a quality factor substantially equal to a quality factor of the first inductor, resulting in attenuation at the resonant frequency. Each of the inductors and capacitors are formed by micro-ribbon technology.

Abstract: A system of transmission with amplitude modulation for the transmission of signals of all types, analog and/or digital, requiring high performance characteristics with respect to the noise induced by the transmission channel, comprising, at transmission, means for the suppressed carrier amplitude modulation of a useful signal and means for the amplitude modulation, in phase quadrature with said modulated useful signal, of a service signal, making it possible, at reception, to remove the ambiguity on the polarity of the demodulated useful signal. Thus it enables the transmission of signals in suppressed carrier modulation mode, hence with a good signal-to-noise ratio, without losing the polarity of the signal. The transmitters and receivers according to the invention also enable the transmission and reception of the signals modulated in SCAM, VSBAM or VSBSCAM modes.

Abstract: A three-dimensional television system uses a method of processing and transmitting a sequence of pairs of stereoscopic television images by means of a transmission link comprising and analog video channel associated with a digital channel to reconstitute at the receiving end a compatible image or a three-dimensional image. The analog video channel transmits a compatible video image formed by multiplexing image items of righthand and lefthand images of pairs of stereoscopic images from the sequence.

Abstract: A method for the regulation of the throughput of assistance data is provided. The assistance date assists in the reconstruction of subsampled moving electronic images. The method is particularly useful for HDTV transmission by a HMAC channel. For each elementary block of the image, an optimal processing operation is selected from first and second parallel processing operations. The second processing operation includes an image filter, and the first processing operation includes a motion compensation process. The first processing operation generates a larger data throughput rate of assistance data than the second processing operation. If the throughput rate of assistance data approaches or exceeds the maximum throughput rate permitted for a transmission unit, the second processing operation which produces a smaller data throughput rate is automatically selected.