摘要:
A system for scrambling a video signal, wherein multiple modes of scrambling are available, including (i) line reversal, (ii) line inversion, (iii) line permutation, and (iv) block permutation. The invention changes the combination of modes used as time progresses. In addition, particular modes can be implemented, or suppressed, in response to such factors as (i) noise in the transmission channel and (ii) amount of motion within the video image.
摘要:
Le procédé de cryptage/décryptage analogique selon l'invention s'applique à un signal vidéo analogique (S) comportant un signal utile (SU) relatif aux lignes de l'image, entrecoupé d'intervalles de retour-ligne (IRL). On fait subir à des parties disjointes du signal utile (SU) une inversion en fonction d'une suite d'informations binaires choisie, possédant une allure sensiblement aléatoire, et l'on obtient un signal vidéo inversé (SI). On peut également ajouter à ce signal (SI) un signal perturbateur (SP) tiré d'au moins une forme d'onde, choisie, quasi-aléatoire. Afin que le signal de sortie soit dans un gabarit normalisé, on peut effectuer une compression du signal vidéo et l'on obtient alors finalement un signal crypté (SCR). Le procédé de décryptage consiste à effectuer des opérations inverses du cryptage.
摘要:
An encrypted video distribution system includes a signal- originating head end for scrambling outgoing television program-bearing signals. In particular, the video content of selected lines is inverted about a reference voltage level, and the inversion reference level amplitude transmitted in pulse form during the horizontal synchronizing pulse interval. Line video inversion/non-inversion is controlled by a keyed pseudo random generator. At each authorized subscriber location, all inverted lines are restored to proper format, using the accompanying received inversion amplitude level present during horizontal sync as a reference. A pseudo random generator is included in the receiver descrambling circuitry and operates in a sequence identical to the like circuit atthe head end to identify those lines requiring video inversion.
摘要:
@ An encrypted video distribution system includes a signal originating station which distributes television signals in a format unrecoverable by a standard television receiver. In particular, the normally occurring vertical and horizonal synchronizing pulses are deleted and, optionally also, video information is selectively inverted about a voltage reference potential intermediate the black and white levels. To permit synchronization restoration, a keying pulse is transmitted once each video field, and a synchronizing digital code burst transmitted once each frame - all at a fixed, predetermined intra-frame timed relationship. At each authorized subscriber location, the keying pulse and digital code burst are employed to lock a receiver frame clock which derivatively gives rise to all requisite reception- permitting synchronizing pulses. The transmitted information also contains information sufficient to restore the inverted video program content.
摘要:
A video scrambling and descrambling arrangement utilizes plural scrambling characteristics including a predetermined scrambling waveform (15) and a selectable one of a plurality of phase relationships (50-57) with respect to the video signal (10) to be scrambled. Descrambling is achieved by combining (117) with the scrambled video signal a correspondingly phase shifted, inverted version of the scrambling signal. Scrambling and descrambling can be implemented in analogue or digital forms. The information required to achieve descrambling is contained in the scrambled video signal, preferably in an unscrambled portion (91) thereof.
摘要:
A system for scrambling a video signal, wherein multiple modes of scrambling are available, including (i) line reversal, (ii) line inversion, (iii) line permutation, and (iv) block permutation. The invention changes the combination of modes used as time progresses. In addition, particular modes can be implemented, or suppressed, in response to such factors as (i) noise in the transmission channel and (ii) amount of motion within the video image.
摘要:
Le dispositif est muni d'un compteur (21) pour compter, pendant un signal de suppression de trame, les signaux de synchronisation de ligne appliqués à son entrée d'horloge (CP). L'entrée (CEP) d'autorisation de comptage du compteur rerçoit un signal dont la durée correspond à la durée de cinq demi-lignes. Le compteur repart à zéro lorsqu'il a compté cinq signaux, en indiquant alors sur une sortie spécifique (TC) que le comptage a atteint cinq, et cette sortie (TC) est reliée à un circuit logique (14 à 18), qui fournit à chaque fin d'intervalle de suppression de trame un signal binaire (19) qui reste inchangé lorsque le chiffre de comptage du compteur a atteint cinq et qui est inversé dans le cas contraire. Ce signal binaire commande un démodulateur pour l'adapter à la polarité. Application : Récepteurs de télévision, soit multistandards, soit dans lesquels il est nécessaire de reconnaître la polarité d'un signal video qui est inversé par rapport au signal normal d'une norme d'émission donnée, par exemple dans le but de renforcer un brouillage.
摘要:
@ An encrypted video distribution system includes a signal originating station which distributes television signals in a format unrecoverable by a standard television receiver. In particular, the normally occurring vertical and horizonal synchronizing pulses are deleted and, optionally also, video information is selectively inverted about a voltage reference potential intermediate the black and white levels. To permit synchronization restoration, a keying pulse is transmitted once each video field, and a synchronizing digital code burst transmitted once each frame - all at a fixed, predetermined intra-frame timed relationship. At each authorized subscriber location, the keying pulse and digital code burst are employed to lock a receiver frame clock which derivatively gives rise to all requisite reception- permitting synchronizing pulses. The transmitted information also contains information sufficient to restore the inverted video program content.
摘要:
A scrambling system of television signal includes a circuit for eliminating vertical sync pulses in a vertical sync pulse period and equivalent pulses in first and second equivalent pulse periods at opposite ends of said vertical sync pulse period. In place of the eliminated pulses, substitute pulses having a frequency equal to an integer times the frequency of horizontal sync pulses are deposited. A framing code inserting circuit is provided for inserting at least one framing code in the substituted pulses. The framing code is carrying information how the television signal is scrambled.
摘要:
A microprocessor based decoder module for television video signals which have been encoded by suppressing sync pulses and/or inverting picture video. The decoder module generates sync restoration gates and/or video inversion gates developed from timing signals present in the VBI of the encoded video signal. The VBI timing signals may be either sync pulses which are not suppressed during the VBI, or special timing signals inserted at the video encoder. The microprocessor, in the decoder module, may contain externally selectable program segments where each segment will allow decoding of a different variety of video encoding.