Method for scrambling and unscrambling a video signal
First Claim
1. In a method of scrambling and unscrambling a video signal, comprising emitting a scrambled video sequence at a transmitting site, receiving the scrambled video sequence in a storage memory at a receiving site and unscrambling the received video sequence, wherein the scrambling comprises successively emitting a group of image lines of the video signal in an order different from a normal order of the image lines which corresponds to an intelligible image,the improvement wherein the storage memory at the receiving site comprises a predetermined number of memory lines each having an address, each memory line is able to store one received image line and, in response to the storage therein of a new image line, simultaneously outputs the image line previously stored therein, andthe scrambling method at the transmitting side comprisesdetermining for each emitted image line an address of the receiving site memory to which the image line is to be sent and stored in an order which is scrambled in relation to the normal order for generating an intelligible image;
- anddetermining at least one of the emitting time and the emitting sequence of each image line so that when each image line is sent to the address of the storage memory at the receiving site, the previous image line stored therein is output in a sequence of image lines in the normal order for generating the intelligible image.
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Accused Products
Abstract
A scrambling method wherein each image line (23-309) of a frame having been produced in unscrambled form before being scrambled, is given the pseudorandomly determined address (B) of the memory line in the storage memory (8) in which said image line is to be stored on reception; and wherein the moment (or the running order) for broadcasting said image line is determined so that on reception, the image line causes, because it is stored in the memory line to which it was addressed, the image line previously stored at the same address to be output to the television set at the right moment (or in the right order) so that an unscrambled picture is reconstructed.
89 Citations
4 Claims
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1. In a method of scrambling and unscrambling a video signal, comprising emitting a scrambled video sequence at a transmitting site, receiving the scrambled video sequence in a storage memory at a receiving site and unscrambling the received video sequence, wherein the scrambling comprises successively emitting a group of image lines of the video signal in an order different from a normal order of the image lines which corresponds to an intelligible image,
the improvement wherein the storage memory at the receiving site comprises a predetermined number of memory lines each having an address, each memory line is able to store one received image line and, in response to the storage therein of a new image line, simultaneously outputs the image line previously stored therein, and the scrambling method at the transmitting side comprises determining for each emitted image line an address of the receiving site memory to which the image line is to be sent and stored in an order which is scrambled in relation to the normal order for generating an intelligible image; - and
determining at least one of the emitting time and the emitting sequence of each image line so that when each image line is sent to the address of the storage memory at the receiving site, the previous image line stored therein is output in a sequence of image lines in the normal order for generating the intelligible image. - View Dependent Claims (2, 3, 4)
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Specification