| 摘要 |
The decoder is capable of locating a data signal within any horizontal line of a video signal, thereby eliminating the necessity for keeping track of the line numbers. The pre-data portion is detected and the data portion is stored in the same register. DC level restoration of the video signal is performed periodically during digitizing. When the decoder is used to receive a data signal in the standard FCC waveform, the clock run in portion, normally used for synchronization in conventional decoders, is detected and the operating rate of the register is adjusted to the rate of the data portion for a number of clock signals equal to the number of data bits to capture the data portion. Once the data has been captured, further signals are prevented from entering the register for approximately one frame to permit the stored data to be retrieved.
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