Abstract: The invention principally relates to a device and to a method for writing in a storage device of the stack type. The invention relates to the use of stacks (1) of the first-in, first-out (FIFO) type for the unscrambling of television images. In order to be able to write in such a stack (1) starting from a desired address, the procedure begins with writing non-pertinent information in order to increment the stack's internal counter to which there is no access. Then, starting from the desired value of the counter, pertinent information is written. It is possible to rewrite pertinent information over the non-pertinent information placed for example at the start of the stack. The present invention applies in particular to the use of special memories for uses which have not been foreseen by the manufacturer. It applies more particularly to the use of stacks (1) of the first-in, first-out type for the unscrambling of television images.

Abstract: The device of the invention for a pay-television system comprises an emitter and several receivers using "smart cards". In addition to the unscrambling control signals, the emitter sends encrypted authentication messages to which a correct response can be given only by the receivers where valid cards are used.

Abstract: The present invention concerns a processing method for a video signal coded in the form of blocks of K words, this signal being written to or read from two frame memories (FM1, FM2) each including an input port, a high speed output port and a low speed output port. According to this method, the input digital video signal is formed by sets of M' blocks with N' block containing luminance data (Y1, Y2 . . . ) and M'-N' blocks containing chrominance data (C1, C2 . . . ), the blocks containing the chrominance data (C1) are written in the first memory (FM1) and the blocks containing luminance data (Y1) are written in the second memory (FM2). Then the blocks containing the luminance data and the blocks containing the chrominance data are read simultaneously on the high speed output port of each memory, the memories being inverted at each frame, and the data eventually being processed to obtain video data in output that presents a compression ratio M/N with M>N.

Abstract: To counter illicit prevention of the invalidation of a smart card in a pay television network, for example when the period of validity for the card has expired, a verification of the card reader's ability to write to the card's memory is made. This verification consists in periodically sending a data item to be stored in the card. A counter on the card is reset by the writing voltage of the card's storage. In the event the writing voltage does not reach the counter, the counter's overflow output is connected to a read inhibition circuit which blocks functions of the card.

Abstract: A device and to a method for generating control signals is set forth. The device according to the present invention allows the generation, from a single time reference, of the write control (WE) and read control (RE) signals for the information relating to a video line in a storage device (7, 8, 17, 18, 20). In this way, possible shifts between the synchronization of two successive lines due in particular to the transmission are overcome. The device according to the present invention is applied in particular to the generation, from a common time reference, of write signals and of read signals for a storage device (7, 8, 17, 18, 20) intended for storing a video image line.The invention applies principally to the production of devices for unscrambling scrambled television transmissions, particularly pay television transmissions.

Abstract: A method for linking data for recording on a recordable type of optical disk with data encoded according to a specific encoding using a CIRC type error correction system. The pieces of data are organized in frames, in blocks of p frames and in groups of n blocks. The frames of data and frames of sub-codes are synchronized by using pieces of information pre-recorded on the disk. During encoding, each group of n blocks receives and is preceded by three redundant blocks, namely a run-in block (RIN) itself preceded by a first dummy block (DMI) and second dummy block (DM2); and is follwed by two redundant blocks, namely a run-out block (ROUT) which is followed by a third dummy block (DM3). During writing on the disk, the length of the three redundant blocks is sufficient. They effectively set-up the record and reading of the data and its interleaving and error correction code. The disclosed method can be applied particularly to recordable optical compact disks.

Abstract: According to the disclosed method, a reference line is caused to be transmitted during the non-visible part of the image, the transmissions are received with a calibrated receiver, this reference line is sampled, an error signal is produced from the difference between this line and its theoretical value, a correction coefficient is deduced therefrom for each of the samples of the line, and this correction coefficient is applied to the lines of the following frames.

Abstract: The process of the invention concerns pay television networks with reinforced scrambling. To attract potential subscribers, the invention consists in cyclically transmitting non-scrambled images for brief periods, so that the type of program can be seen.

Abstract: Disclosed is a method for the processing of digital control data associated with an HD-MAC type video signal as well as a device for the implementation of the method. In this method, during one processing period, the digital control data associated with the video signal of the following processing period is decoded. The digital control data corresponding to n successing processing periods (n.gtoreq.2) is stored and then the data thus stored is decoded on a time sharing basis so as to achieve the output, in parallel, of the desired pieces of digital control data with their specific delay. Application to high-definition television.

Abstract: To allow teleshopping to be performed quickly and reliably via the television network, receivers (3) are equipped with smart card readers (4), and the transmitter (2) sends information which is processed in the smart cards by means of the viewers' control devices (6). The result of this process is displayed on the screen and communicated later to the transmitter. This result allows the viewers' reactions to be authenticated.

Abstract: To prevent a person having found or stolen a card of a pay-television subscriber from using it fraudulently, the identity of the subscriber is recorded in a zone protected from reading and writing. At the beginning of the period of use of a new card, the new card compares the identity of the new card with that of the old one, and delivers the password only if the two identities are the same.

Abstract: A limiter device essentially includes a comparator connected to a capacitor charged by a current proportional to the beam current and short-circuited by pulses during one line just after the frame return pulses. This comparator receives a threshold voltage and its output is connected to a capacitor connected to another reference voltage, and this comparator is validated by the frame return pulses.

Abstract: Reader for smart cards comprising a supply for the circuits of the card, a means of controlling information exchanges between the card and the reader and an input for digital signals from a pay-television system. The means of control comprises a first microcontroller which receives the digital signals and which controls a second microcontroller which itself controls the exchange of information with the card and delivers power supply control signals as a function of the information received from the card. The outputs from the first microcontroller are at a fixed potential during the resets and the outputs from the second microcontroller are at a floating potential during the resets. A port enables the first microcontroller to control the power supply during the resets.