Abstract: The radar system of the invention uses a digital television network to make a multistatic configuration. The transmitted signal is of the OFDM type. The receiver or receivers carry out a matched filtering operation and recover the synchronization by processing of zero-value Doppler gates.

Abstract: A method comprising breaking an image down into sub-bands, performing a pre-analysis of the image in image blocks, recursively and adaptively assigning the available bit-rate to each pixel in the sub-bands, selecting a quantizer determined by the source probability density and a calculation of the minimum quantizing error variance, and coding each pixel of each signal component in every sub-band according to the selected quantizer. The method is applicable to HDTV digital VCRs.

Abstract: A coder comprising banks of analysis filters (26, 27) for partitioning the spatio-temporal spectrum of each television image into sub-bands. The banks of analysis filters are coupled to devices for differential coding (30.sub.i, 31.sub.i, 32.sub.i) for separately coding the signals obtained in each sub-band. The decoder comprises prediction loops (24; 25; 12, 17 . . . 20, 3, 21, 22, 23) equal in number to the number of sub-bands for reconstructing each television image transmitted by the coder portion together with its level of resolution in each of the sub-bands.

Abstract: The method of the present invention is directed to information compression which allows for compatible decoding of a group of television signals with increasing resolutions. According to the present invention, a first step, at the transmitter, involves strobing the space frequency band of the signal to be transmitted which has the highest resolution into adjacent subbands. Then, the signal with the highest resolution to be transmitted is independently coded in each subband. The subbands are then multiplexed by separating the coded signals in each subband by means of non-imitable synchronizing patterns. At the receiving decoder, the signals received relative to each subband are decoded only taking into consideration those which are necessary in order to reconstitute at least one member of a resolution group. The present invention finds particular application in the transmission system for high-definition TV images.

Abstract: The present invention relates to a method and apparatus of encoding and decoding blocks of data words. Each block has a fixed number of data words with a maximum of nbits, and a position of a data word within a block is diagonally identified by a series of absolute addresses having consecutive values. In the encoding of the data words of a block, the data words are classified into groups based on their most significant non-zero bit. Then the corresponding absolute address of each classified data word is encoded based on the absolute address of a previously encoded data word in the same class as the current classified data word and the number of data words encoded in classes less than the current classified data word since the previous encoding of a data word in the class of the current classified data word. Each data word with its ith and greater bits omitted is then transmitted along with the encoded absolute address.

Abstract: A variable length encoding method for encoding a finite or infinite series of values corresponding to a random variable whose distribution monotonically decreases on either side of the mean value in which the encoding tree has a regular structure which is defined by an arithmetic and logic device. In order to encode each value E, a first binary word, including only bits having a same value and whose number of bits B is an increasing function of the value to the encoded E, is determined. The number of bits B is computed according to a predetermined arithmetic and logic function B(E). The method also involves determining a second binary word having a value to be encoded, in the set of values to be encoded arranged in order of decreasing probability, and whose number of bits B' is derived from the function B(E) and from the number of bits B in the first binary word. A code word is formed by combining the first and second binary words thus determined.