Coding system for pay television
First Claim
1. A coding system producing an encode control signal for encoding a television signal by inverting at least a part of the television signal, which comprises:
- a first means for generating first random code signals;
a second means for generating second random code signals corresponding to a predetermined value of said encode control signal; and
a third means for inserting the first random code signals into the first five lines of the first six lines within a vertical blanking period of said television signal and the second random code signal into the sixth line to produce said encode control signal,said second means including;
a clock-pulse generating means;
a counter means for counting clock pulses from said clock-pulse generating means;
an inversion mode generating means for producing inversion mode signals indicating a plurality of inversion modes;
a program indicating means for producing program indicating signals;
a setting means for providing predetermined signals in response to outputs from said counter means and said program indicating signal;
a coincidence means for producing a coincidence signal when the mode signal and the predetermined signal are in a predetermined relation; and
a means for producing the second random code signal corresponding to the count value of said counter in response to the coincidence signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A coding system for use in a television system wherein at least a part of a television signal is inverted by an encoder at a broadcasting station, according to a code signal and the coded television signal is decoded by decoders of specific subscribers to be reproduced on TV sets. The coding system is comprised of a clock oscillation means, a mode generating means for generating signals indicating plural inversion modes, a counter for counting clock signals from the clock oscillation means, a setting means for outputting a predetermined signal based on addresses provided corresponding to the respective inversion modes of the mode generating means and determined by an output from the counter, and a means for inserting the code signal during a vertical blanking period of the television signal. When the output signal of the mode generating means and the output signal of the setting means are in a given relation, the count value of the counter is used as the code signal.
114 Citations
5 Claims
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1. A coding system producing an encode control signal for encoding a television signal by inverting at least a part of the television signal, which comprises:
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a first means for generating first random code signals; a second means for generating second random code signals corresponding to a predetermined value of said encode control signal; and a third means for inserting the first random code signals into the first five lines of the first six lines within a vertical blanking period of said television signal and the second random code signal into the sixth line to produce said encode control signal, said second means including; a clock-pulse generating means; a counter means for counting clock pulses from said clock-pulse generating means; an inversion mode generating means for producing inversion mode signals indicating a plurality of inversion modes; a program indicating means for producing program indicating signals; a setting means for providing predetermined signals in response to outputs from said counter means and said program indicating signal; a coincidence means for producing a coincidence signal when the mode signal and the predetermined signal are in a predetermined relation; and a means for producing the second random code signal corresponding to the count value of said counter in response to the coincidence signal. - View Dependent Claims (2, 3, 4, 5)
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Specification