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 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.

Abstract: A method provides greater reduction in the throughput rate and, at the same time, greater fidelity to the configuration of an HD source image. The method is applied to a multiprocessing system wherein, within the picture or picture image blocks, "neutral" processing mode picture elements are determined, namely picture elements capable of accepting, without discrimination, at least two distinct sub-sampling processing modes; and it is chosen to associate, with each of the neutral processing mode picture elements, the one of the neutral processing modes that enables an optimal reduction in the throughput rate of the assistance data.