Abstract: An image coding method for a domain corresponding to at least one portion of an image. A minimal triangular partition covering the domain is defined. A square matrix is associated with each of the source triangles by a first reversible transformation so that each matrix represents a specific source triangle. A second reversible decorrelation transformation is applied to each square matrix, resulting in transformed matrixes. The method may be used in isolation, or as a supplement to another coding of the hierarchic type. A corresponding decoding method is also provided.

Abstract: The invention concerns a graphic scene animation data signal, designed for means constructing images capable of being displayed on at least one screen, said graphic scene having probably been loaded in said means constructing images, in the form of a set of objects, some of said objects at least having its own particular identifier, said signal comprising: a single animation mask, delivered as preamble to said animation, and assigning at least one of said objects to an elementary mask comprising: said object identifier, as defined in said graphic scene to be animated; and the designation of at least one dynamic characterization field of said object, representing a characteristic of said object capable of being modified; animation frames, comprising, according to the order defined by said mask, data updating said object dynamic characterization fields, so as to modify them, said constructing means decoding said animation mask data, and initializing the animation of the basis thereof, and updating the scene on

Abstract: A method for the time synchronization of a multi-carrier signal receiver consisting of a sequence of symbols each formed by a plurality of carrier frequencies. Each carrier frequency is modulated by a modulation coefficient. The position of some of said carrier frequencies in the time-frequency space is known to the receiver, and said frequencies are reference carrier frequencies. Each reference carrier frequency bears a reference coefficient with a value that is known to the receiver. The method includes a fine synchronization step, wherein the signal transmission channel impulse response is estimated on the basis of reference coefficients belonging to at least two received symbols. The beginning of the useful portion of each of the symbols is determined, and/or a receiver clock is controlled by analyzing the estimate of said impulse response.

Abstract: The invention concerns a multicarrier signal designed to be transmitted to digital receivers, especially in a non-stationary transmission channel, corresponding to the frequency multiplexing of several elementary carriers each corresponding to a series of symbols, two consecutive symbols being separated by a symbol time &tgr;0, a signal in which, firstly, the spacing &ngr;0 between two neighboring carriers is equal to half of the reverse of the symbol time &tgr;0 and, secondly, each carrier undergoes an operation of filtering for the shaping of its spectrum having a bandwidth strictly greater than twice said spacing between carriers &ngr;0 and is spectrum is chosen so that each symbol element is highly concentrated in the temporal domain and in the frequency domain. The invention also concerns the methods for the transmission and reception of such a signal.

Abstract: Disclosed are a method and a device for the convolutive encoding of blocks each formed by a predetermined number N of source data elements, wherein each of said source data elements is introduced twice into one and the same convolutive encoder implementing a generating polynomial with a period L in an order such that the two instances of introduction of one and same source data element d.sub.i are separated by the introduction of (p.sub.i.L)-1 other source data elements, p.sub.i being a non-zero integer. Also disclosed are a corresponding decoding method and device that can be applied, in particular, to the transmission of short messages, for example in radiotelephony, for satellite communications or gain computer telecommunications (Internet for example). FIG. 2.

Abstract: A method for the dynamic reconfiguration of a signal frame structure, wherein each frame is structured in at least one subchannel having a number, order and/or format capable of being altered under the control of a reallocation command, time interleaving on N frames being selectively performed for each subchannel. According to the method, in the transient state, and for the N frames following a reallocation command, the procedure for writing data elements according to the interleaving law remains unchanged, in accordance with the new structure defined by a reallocation command, and a specific logic for rereading the memory plane is implemented so that the frames consist of uniform capacity units comprising data elements from the same source signal. The corresponding transmitters, receivers and signals are also disclosed.

Abstract: A method for filtering a time signal (e(t)) sampled in blocks of N samples (e(n),e(k)) uses a transfer function defined in the frequency domain by LN samples (H(K)). The transfer function is filtered by a time window (g1) of width N, and a frequency subsampling of ratio N is performed to give a partial transfer function defined over N samples (H1(k)). The method enables the complexity of circuits operating in real time to be optimized. The technique is particularly suitable for correcting long echoes in television picture receivers.

Abstract: A method for the decoding of digital data obtained according to a convolutional coding and transmitted on a noise-ridden channel aimed at improving the methods of maximum likelihood decoding such as the Viterbi algorithm consisting in associating, with each estimation s(t) of the corresponding source digital element a(t), a weighting coefficient m(t) representing the reliability of the estimation s(t), the estimation s(t) taking account of the values of a first series of L received samples, and the weighting m(t) taking account of the values of a second series of N samples received, N being strictly greater than L. In a preferred embodiment, a second trellis is associated with the standard first decoding trellis, a trace-back being done in the second trellis on two concurrent paths, used to revise the weighting coefficients obtained at output of the first trellis.

Abstract: A device for the reception of digital data broadcast at a high bit rate for reception by mobile receivers is disclosed. The device operates under adverse conditions of multiple propagation corresponding to the Rayleigh process and imperfect frequency tuning to minimize the inter-symbol interference in the frequency domain. The device receives a digital signal having digital elements distributed in the frequency-time space f-t and transmitted in the form of symbols each constituted by a multiplex of N orthogonal carrier frequencies modulated by a set of digital elements and broadcast simultaneously. The device includes a module for transposition by a local oscillator, baseband filtering and analog-digital conversion, a temporal windowing module for the selection of the useful samples and a mathematical transformation module, the temporal windowing module applying a Nyquist window type of temporal window with non-zero roll-off.

Abstract: Method of electronic payment by chip card.According to the invention, each token carries a number making it possible to check its authenticity.The invention is used for electronic payment.

Abstract: In accordance with the present invention, the number of bits used to code a frame of video is controlled by controlling the frame size. In a preprocessing stage (40) of a video coding circuit (10), each frame of video is processed by a low pass anti-aliasing filter (43,44) in the horizontal and vertical directions. The cutoff frequencies in the horizontal and vertical directions are determined by a desired frame reduction factor in the corresponding direction. Then to reduce the sampling rate in each dimension, each frame of video is processed horizontally and vertically by a shift varying filter (45,46). When the sampling rate in both the horizontal and vertical directions is reduced by M/N, the number of code bits decreases linearly with M/N.