Abstract: The present invention relates to methods which make it possible to partially eliminate the redundancy in television signals. It consists in splitting the spectrum of the video signal into two parts, one containing the low frequencies, this being transmitted integrally, and the other containing the high frequencies, this being transmitted once every n times and being repeated n-1 times at reception.

Abstract: The present invention relates to the dissemination of binary digital data by analogue transmission or storage. The object of the invention is a communication system in which, prior to dissemination, the binary data are grouped into blocks forming vectors with N components, which are transformed into orthogonal vectors with N analogue components; after dissemination, the vectors experience a reverse transformation which makes it possible to reconstitute the binary digital data.

Abstract: The device comprises a flexible magnetic sheet reflective on one side, at least one magnetic circuit associated with at least one zone of the sheet for deforming the sheet by a modification of the magnetic flux in the magnetic circuit. Exciting means controlled by electrical data vary the magnetic flux so as to modify the reflecting conditions in said zone as a function of the electrical data.A unit for recording holographical optical memories is disclosed which employs this device.

Abstract: A high operational reliability modulator, constituted by a mosaic of elements having variable double-refraction properties. It comprises, on a flat ferro-electric ceramic structure and in respect of each element, a first conventional pair of transparent electrodes and a second pair of distinct electrodes, made of transparent photoconductive material; by the application of illumination, the second electrodes are rendered conductive exclusively at the required instant, thus avoiding any interim disturbance to the action of the first electrodes and enabling the change of double-refraction properties of the ceramic.