Enhanced security for a cable system
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United States of America Patent
Stats
-
Feb 13, 1996
Grant Date -
N/A
app pub date -
Mar 1, 1994
filing date -
Mar 1, 1994
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A cable television plant scrambling system incorporates video inversion with a pair of mode signals included in the vertical blanking interval of a scrambled television signal for identifying the proper mode for a video inverting/non-inverting amplifier at a subscriber station. An encoded mode control signal in the form of a byte of data is sent periodically with the scrambled television signal for selecting which of the mode signals is operative. In the receiver, the mode signals are applied to the inverting/non-inverting video amplifier and the encoded mode control signal is supplied to a microprocessor which is provided with a decoding algorithm from the cable head-end. The microprocessor decodes the mode control signal and tells the inverting amplifier which mode signal to look to for proper operation. A new decoding algorithm is periodically downloaded to subscriber stations on an out-of-band basis to enable the encoded mode control signal to be changed.
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Family
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Cited Art Landscape
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