Other

France Telecom

Telediffusion De France

Etablissement Public De Diffusion Dit 'telediffusion De France'

Jean-Claude Rahuel

Catherine Roux

Jean-Paul Dagnelie

Daniel Pommier

Alain Bache

Robert Veilex

Edouard Guillouet

Bernard Lorig

Digital signal organized in self-contained data containers, especially

A method for the transmission of digital data elements including radio paging information elements, wherein the data elements are transmitted according to a technique of transmission implementing a plurality of orthogonal carrier frequencies (the COFDM technique), the signal being organized in frames comprising, firstly, at least one first channel called a fast information channel, comprising at least one symbol of data elements, the carrier frequencies of the symbols being modulated by data elements that are not temporally interleaved, and at least one second channel, called a main channel, comprising at least one symbol of data elements, the carrier frequencies of the symbols being modulated by data elements that are temporally interleaved beforehand, a frame number belonging to a set of predefined frame numbers being regularly inserted into the fast information channel, each of the radio paging receivers being assigned at least one of the frame numbers.

Method for the transmission of digital data in radio paging systems and

The process concerns the plotting of overextending curves inside a limited display window, with cutting-off of the parts of the curve which extend beyond the imposed display window. The goal is to provide a process for the plotting of overextending curves inside a display window, which optimizes calculation time and plotting time. This goal is achieved by means of a process characterized in that it manages a first process for plotting, applicable to the portions of curves (55) inscribed inside the window, and a second distinct process for processing of the overextending parts (54) of the curve, in that the processing of the overextending parts consists in optimizing travel (51, 52, 53) along the projection of the overextending parts on the window border (X.sub.max, Y.sub.max), and in that the said processing process is entirely executed within the plotting process, and in the course of the plotting of the curve.

Process and circuitry for implementing plotting of overextending curves

The present invention relates to a device for the digital transmission and display of graphics and/or of characters on a screen, the device comprising a terminal connected to a transmission network, to a graphic acquisition device and to a unit for display on a screen. Each terminal comprises a storage unit which, according to the invention, comprises a plurality of storage assemblies validatable in parallel, each storage assembly comprising a circuit effecting a logic combination between an input word and the word already written at the address indicated. The invention is more particularly applicable to the production of telewriting systems or of combined systems of telewriting and videotext (viewdata).

Device for the digital transmission and display of graphics and/or of

The apparatus comprises a wire sheet graphics tablet and a display apparatus, particularly a cathode ray tube, for receiving the signals transmitted by the graphics tablet. Alternating current flows through wires (5,6) of the tablet. The non-conducting plate (4) of the tablet is transparent and the wire sheets (5,6) are made up of transparent electrical conductors or of small conducting wires, which makes them practically invisible. The tablet is placed on the screen of the display apparatus. Between the screen of the cathode ray tube and the lower side of the graphics tablet, a transparent conducting and non-magnetic coating (8) is provided. In one variation, the current flowing through the layers of wire (5,6) is a high frequency current. The pen for the graphics tablet may be a metallic rod covered by a sheath of insulating material.

Teletext and display apparatus for general surface

A graphics table comprises a non-conductive plate supporting two crossing layers of wires and a pen for writing on a sheet disposed on the plate. The wires are successively scanned by an electric current which creates a field to be detected by the pen. The electric current has a high frequency, for example of the order of ten megahertz, and the wires are switched at a frequency of for example one hundred kilohertz. The pen is followed by a selective amplifier of ten megahertz, by a filter, by a detector, and by a circuit for determining the time when the picked up signal passes through a peak. The invention is notably useful in a telewriting system.

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Rennes, France

Jean-Claude Rahuel