Abstract: A text video-transmission system comprising an information emitting center and receiving stations, the emitting center comprising encryption means using an operating key, each receiving station comprising decryption means using the operating key, wherein in this system, the encryption means of the emitting center comprise: a generator delivering a numerical signal representing an operating key K, this key changing randomly at predetermined intervals; an automatic encryption means comprising: a discriminator with an input connected to a magazine memorizing circuit from which it receives clear octets, this discriminator being capable of distinguishing, among these clear octets, those wherein the 7th and 6th binary elements are zero, an OR-exclusive logic circuit connected to the discriminator from which it receives octets wherein the 6th and/or 7th binary elements are not zero, this logic circuit having an output which carries encrypted octets; a generator of encoding octets, the decoding means of each receivin

Abstract: A system for transmitting information between an emitting center and receiving stations, comprising: a subscription administration center generating a plurality of subscriber's keys C.sub.i changing randomly at relatively long intervals of the order of a month; in the emitting center: a generator of an operating key K changing randomly at relatively short intervals of the order of a few minutes; a circuit for forming messages M.sub.i obtained from said subscriber's keys C.sub.i and from the operating key K by means of an algorithm, all the messages M.sub.i then being directed towards the emitting center; and automatic encryption means using the operating key K, in each receiving station: a subscription holder on which is recorded a signal corresponding to at least one of the subscriber's keys C.sub.i ; a circuit for restoring the operating key receiving the messages M.sub.i and the subscriber's key C.sub.

Abstract: A method of aligning videotex characters on the screen of a television set, said characters being arranged in horizontal rows each occupying a number of scanning lines, wherein the vertical dimension of the characters and therefore of the rows may be doubled by repetition of the display of a line in the following line, said method comprising the steps of reading the data of a row during the scanning of the first, not displayed, line of said row and adjusting the alignment of the characters in accordance with the read data.

Abstract: In a system for broadcasting data in combination with a television signal, he emitting station broadcasts, sets (blocks) of data which may be in-coming from several paths, the sets of data being time multiplexed. The present invention makes it possible to use the same television broadcast system, regardless of the television standards which may be used, with a minimum of modifications in the conventional television receivers. The frequence of the binary elements used to transmit data is made to vary as a function of the band width of the television signal which in turn, corresponds to the TV broadcast used in the area where the data is broadcast.

Abstract: A method for addressing a page memory in a videotex system, said page memory being capable of storing the character data required for displaying one page of text, each page comprising 25 rows of 40 characters each, the first row being a service row, said memory having 1024 available positions, wherein the 24 positions not dedicated to character data are respectively allocated to the 24 rows other than the first row for reading out data common to all the characters of the row in consideration.

Abstract: A page selection device for a videotext system in which the incoming data are arranged in blocks comprising a data group following a prefix, some of the blocks having within said group specific codes called page headers, a page comprising the data between a page header and an end of page code, the page to be displayed being transferred to a page memory, said device comprising an input buffer having a capacity of at least one block, in which data are entered as they appear, an additional buffer with a capacity of at least one block, in which the incoming data are only entered if a page header has been detected, a main buffer with a capacity of at least one page, in which the content of the input buffer is transferred when a page header is detected, and means for comparing the page number entered in the additional buffer with the selected number and for controlling, according to whether the comparison is positive or not, either reading of the data entered in the main buffer for transfer to said memory or resett

Abstract: Videotex system provided with protection means against transmission errors.It can be used in the transmission and display of data on television recers for entertainment, information or instructional purposes.

Abstract: An encrypting and decrypting system employing analog signals in which delay lines are employed in both the encrypter and decrypter so that the initial analog signal which is received may be switched by switching means to a writer means where encrypting occurs in a delay line in which stages are filled in a predetermind clock period. Another delay line similar to that used for the writer means and this other delay line is used for reading the written stages from the first delay line according to the predetermined time distribution. Decrypting is carried out by inverting the foregoing encrypting operations. Various types of cynchronization are shown. Both read and write controls are shown.

Abstract: The system combines first and second composite video signals into a resulting composite video signal. The first composite video signal represents a foreground scene having a first trichromatic moving picture region which envelopes a second trichromatic backing region through a trichromatic transition region. The second composite video signal represents a background scene. A gain controlling circuit produces from first component video signals first and second analog signals (1-.alpha.), (.alpha.) which control in proportion the amplifications of the first and second composite video signals to obtain second output composite video signals. The first analog signal has first and second levels when the first component video signals are representative of the first and second picture regions and has intermediate levels lying between the first and second levels when the first component video signals are representative of the transition region.

Abstract: A system for transmission and display of texts on a television screen enables a display of a magazine made up of several pages. The packets of data relative to one page are transmitted without being multiplexed with the packets from another page of the same magazine. The data of one page begins with a page flag which is followed by data indicating the number of the page and ends with the flag of the following page. The data from each page is grouped in rows, preceded by a row flag.Each page contains an order row of the data which is operation data and is not used for display. Certain pages contain only the data which is relative to the shape of characters of the alphabet and the pages are not for display. They include in their order rows a specific operation octet which is recognized in the receiver. Responsive to this page, the system switches the subsequent data from the alphabet page towards the writing circuit of one of many shape memories, in order to record there the character shape data.

Abstract: A system for broadcasting data makes it possible to broadcast facsimile d toward a plurality of telecopying apparatuses, using an asynchronous broadcasting network.To each telecopying device there is joined a reception juncture device which develops a going time base or clocking to synchronize the telecopying device. At the emitting station, an emission juncture device simulates the operation of a reception juncture device to govern the transmission of the signal by the network.

Abstract: A bidirectional telewriting system for two-way transmission of telewriting ata over a transmission channel which is shared by a speech link. A frequency window is used within the speech frequency band, within which a single carrier is used. A commutator at each terminal causes a reversal in the direction of transmission of the telewriting data over the single carrier.

Abstract: In the disclosed teletext system, the transmitter station broadcasts data cks data from several channels, the data packs being time multiplexed. Each data pack comprises a prefix signal for causing a teletext receiver either to accept the data packs of a selected channel or to reject data packs from other channels. In addition to the prefix, and possibly page flags followed by page numbers and row flags followed by row numbers, the sequence of eight-bit words, transmitted in a pack, may comprise escape eight-bit words which are followed by type identity eight-bit words, themselves followed by a sequence of characters to be displayed in the same type the identity of which is determined by the preceding type identity eight-bit words.

Abstract: Device enabling the direct measurement of the overall insulation level of an acoustic insulation medium with respect to a reference excitation noise signal when said medium is subject to an actual excitation noise signal deviating from the reference excitation noise signal. The device comprises two microphones receiving a first and a second alternating signal respectively representing the noise signal actually transmitted through the medium and the actual excitation noise signal and a read only memory storing spectral components of the reference excitation noise signal in a plurality of given spectral bands. The first and the second alternating signals are decomposed into alternating spectral components in these spectral bands and the alternating spectral components of the second signal are rectified in order to obtain rectified spectral components.

Abstract: Prefabricated element arranged on a single wall of a room for forming a double sound insulating and sound absorbing wall. The prefabricated element provides efficient sound insulation of the room and a total sound absorption of sound waves whose frequency is centered at one of the natural frequencies of the room. The element comprises a frame supporting a flexible panel by means of elastic sealing means, the flexible panel being maintained at a predetermined distance from the single wall due to the thickness of said frame whereby the resonant frequency of the double wall becomes equal to a natural resonant frequency of the room corresponding to sound waves propagating perpendicularly to the single wall. In addition, the prefabricated element may also comprise an additional element placed in the middle of the panel which permits equalization of the natural resonant frequency of the assembly comprising the flexible panel and the additional element to the low natural frequency of the room.

Abstract: An arrangement for the electrical control of the keyboard of a video or audio tape recorder includes electromechanical levers acting on the usual rod system associated with the keyboard in substitution of the conventional keys. The levers are essentially bellcranks and are associated with tumblers and electromagnets.

Abstract: A reverberation apparatus is adapted for mechanical matching characteristics and comprises at least one reverberation unit comprising a plurality of lattice construction systems of coil springs for transmitting sound-frequency mechanical vibrations, each spring system of which is connected to an electro-mechanical driver transducer and to a mechanical electrical pick-up transducer. Each system of coil springs forms parts of a lattice in at least two dimensions and in the system, the coil springs are mechanically interconnected at a number of coupling points. In each system of coil springs at least some of the coil springs are connected to a rigid frame.

Abstract: There is provided a one-way data transmission system wherein a transmitter station transmits in the form of data packs data from a plurality of channels, the said packs being time multiplexed.One channel amongst the plurality of channels is allotted to transmitting date information. In the receiver equipments, the dead memory stores not only the channel code, but also a subscription period information which permits to validate the channel code depending on the date information received from the date channel. Automatic dead-memory distributors are provided which receive data from a control channel transmitted by the system, like other channels. The system is compatible with television systems.

Abstract: A television video signal is used to record a television picture onto a photographic film.The television video signal is sampled, then digitized. Luminance data and chrominance data, if any, for each sample are stored in a memory. Then, such data is read out and selectively applied to an electro-optic device, such as one, for instance, made of electro-luminescent diodes. The diodes generate either monochrome or trichrome luminous points which are recorded on film by means of a photographic camera. Means are provided for eliminating frame interlacing and for using substantially a standard camera.The system may be used with any television standard.

Abstract: A video titling device for color television pictures wherein the color transmission system is of the SECAM, NTSC or PAL types in which the luninance signal and chrominance signal making up the composite video signal are separate signals. A part of the luminance signal spectrum Y is extracted from the input video signal having a chrominance subcarrier S.P. carried through a single filtering step without modifying the composite input signal. Thus from the composite input video signal of luminance signal Y and chrominance signal S.P. (Y + S.P.) through a single filter, the subtraction of the amplitude of a direct predetermined luminance signal K from the amplitude of luminance signal Y provides a (Y-K) signal. This Y-K signal is then cut out by switching means at a reference voltage under the control of a switching signal representing those selected pictures for the titling operation, and the aforesaid cut out signal is then subtracted from the input video signal (Y + S.P.).