Cable television system having dynamic market code shuffling

摘要: A cable television system includes a headend unit having plurality of program signal sources, encoders, scrambling circuits, and channel modulators for producing channels modulated at corresponding carrier frequencies. An address computer within the is operative upon encoders to provide insertion message packet vertical blanking interval signals. The scrambler circuits render unviewable by conventional receivers. decoder coupled tuner, intermediate frequency amplifier detector. processor selection input tuner in accordance with user input. examines during determine authorization display received channel. descrambler IF detector descramble if detected. modulator modulates descrambled fixed application receiver.