| 摘要 |
Method and apparatus for encoding and decoding a stream of digital (binary) data on AGC (automatic gain control) pulses or back porch pulses of the type conventionally used for copy protection in the analog television or video realm. The data is encoded onto the tips of the AGC or back porch pulses added to blanking intervals of an analog video signal. Each pulse tip may define, for instance, 10 to 15 digital bits (1 or 0) in the form of square waves or rectangular waves with two states, high and low, representing respectively 1 and 0. In another version, the digital data is similarly encoded onto the pulse tip of back porch pulses present at the end of video fields for copy protection. This digital data conveyed in an analog signal may be read by an associated decoder in a consumer device and the resulting data decoded, for instance, for copy control, storage permission, network access, user identification, or carrying additional data, such as commentary or text relevant to the accompanying video. The data bandwidth here is substantial since each AGC or back porch pulse may carry, for instance, 15 bits of digital data and the AGC or back porch pulses may be present in each of the horizontal and vertical blanking intervals of a video signal.
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