Abstract: The present invention relates to a process for transmitting a digitized signal according to OFDM (Orthogonal Frequency Division Multiplexing) type multicarrier modulation using N orthogonal channels. In accordance with the present invention, the channels are divided into two, N/2 channels. corresponding to a first frequency band being sent via a first transmission track (3A, 4A, 5A, 6A, 7A) according to a first polarization and the remaining N/2 channels being brought back into the same frequency band and sent via a second transmission track (3B, 4B, 5B, 6B, 7B) according to a second polarization crossed with respect to the first.

Abstract: The present invention relates to a method of binary encoding the N points of a constellation corresponding to the discrete positions, in amplitude and in phase, associated with the encoding of binary words in the case of a multicarrier modulation of OFDM type (Orthogonal Frequency Division Multiplexing) of a digitized signal. According to the method, two adjacent points of the constellation correspond to binary words which differ from one another by at most two bits. The present invention applies in particular to digital television.

Abstract: The present invention relates to a method of realigning the local oscillators of a receiver, as well as a device for implementing the method. In a receiver with a high frequency/intermediate frequency translation oscillator, an intermediate frequency/baseband translation oscillator, and a sampling oscillator receiving a signal modulated by at least one circuit for inverse fast Fourier transform FFT.sup.-1 computation according to a multicarrier modulation of OFDM (Orthogonal Frequency Division Multiplexing) type with addition of a transition interval at the start of each transmission interval. The spectrum of the signal has two master lines with a fixed frequency difference between them.

Abstract: A transmission method and a transmitter and receiver Structure is disclosed which provides for transmission of modulated waves using long pulses with a plurality of frequencies. The method involves two consecutive frequencies being separated by 1/T, where T is the period of the useful transmission intervals. The method and the apparatus are particularly suited to broadcasting and reception of television and radio signals as well as telephone communications between exchanges and between radio telephones and communication stations including terrestrial stations and satellites and local computer networks. Most particularly the method is applicable to high fidelity radio transmissions as well as to high definition television (HDTV).

Abstract: A device and a method for the transmission or storage of data optimizing the use of the pass-band. Also, a method for transmission by phase modulation. In order to obtain high data throughput rates, the synchronization of a transmission clock with the reception clocks is used. This synchronization is gotten, for example, by transmission of a pseudo-random code and by the convolution or correlation of the received signals with the pseudo-random code. The invention also enables the elimination of multiple echoes by computation. The invention can be applied chiefly to the transmission of radio programs, television broadcasts or digital data.

Abstract: A data transmission and/or acquisition device and method are disclosed. The said device and method use two cross polarizations of an electromagnetic wave and a magnetic recording device. The invention pertains to phase/amplitude modulation using two phase-modulated signals transmitted on two orthogonal polarizations. At reception, the vector sum of the two signals is added taken. The resultant signal is amplitude-modulated and/or phase-modulated. The invention can be applied especially to television and radio transmitters, radars and telecommunications equipment.

Abstract: A projection display device is provided with a negative feedback chain designed to correct all the faults of the projected image, said faults resulting as much from the projection tubes and from their optic systems (geometrical or focusing faults) as from the differences between these tubes (faults in convergence, colorimetry or uniformity of brilliance). The negative feedback chain comprises a test chart generating means, a means to retake the entire projected image and means for the comparision of the signals coming from the test image and from the retaken image. Correction signals are prepared on the basis of this comparison and are applied to the different control circuits defining the projection characteristics. The disclosed device can also be used for the real-time follow-up of the adjustments obtained in a phase prior to the projection of the sequence of useful video images. The invention can be applied notably to video projectors, retro-projection display devices or beam-index tubes.

Abstract: An automatic defect correction drive utilizing feedback in an image display device. According to the present invention, during an acquisition phase, a test image constituted of bright points of known positions distributed on a screen is displayed. This displayed image is then analyzed via an image acquisition device, to deduce from it the scanning, focusing and amplitude corrections to be applied to the display, so that the test pixels displayed on the screen have their expected positions and characteristics. These corrections are then interpolated for the intermediate pixels between test points, and then, during a continuation phase, these corrections are updated.

Abstract: A data transmission and/or acquisition device and method are disclosed. The said device and method use two cross polarizations of an electromagnetic wave and a magnetic recording device. The invention pertains to phase/amplitude modulation using two phase-modulated signals transmitted on two orthogonal polarizations. At reception, the vector sum of the two signals is added taken. The resultant signal is amplitude-modulated and/or phase-modulated. The invention can be applied especially to television and radio transmitters, radars and telecommunications equipment.

Abstract: The present invention concerns mainly a filter, a phase-measuring device and a method to apply said filter. The main object of the invention is a phase-measuring device. The use of adapted filters (140) enables the increasing of the signal/noise ratio of a received signal. However, if several samples of the signal are sent, each having a different phase, the signal present at the output of the adapted filter at any given instant risks being a mixture of the phase of two successive samples. The use of an odd value filter (141) makes it possible to determine the only instants during which the phase measurement corresponds to the phase of a single sample of the signal. The invention can be applied chiefly to the demodulation, detection or decoding of television and radio broadcasts or phase-modulated data transmissions.