Frame sync signal for digital transmission system
DCFirst Claim
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1. A method of operating a digital transmission system comprising:
- formatting a signal having a plurality of segments of multilevel symbols arranged in frames of two fields with each field having a field sync segment and each segment having a segment sync;
generating a first symbol sequence;
generating a second symbol sequence that is shorter than the first symbol sequence;
multiplexing the segment sync and the first and the second symbol sequences to form a field sync segment; and
alternating the polarity of the second symbol sequence in successive fields of the frames.
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Abstract
An ATV signal includes a field sync reference having a relatively long pseudo-random number symbol sequence followed by three relatively short pseudo-random number symbol sequences, with the middle of the three short pseudo-random number symbol sequences having inverted polarity in alternate fields.
171 Citations
15 Claims
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1. A method of operating a digital transmission system comprising:
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formatting a signal having a plurality of segments of multilevel symbols arranged in frames of two fields with each field having a field sync segment and each segment having a segment sync; generating a first symbol sequence; generating a second symbol sequence that is shorter than the first symbol sequence; multiplexing the segment sync and the first and the second symbol sequences to form a field sync segment; and alternating the polarity of the second symbol sequence in successive fields of the frames. - View Dependent Claims (2, 3, 4)
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5. A method of operating a digital transmission system comprising:
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formatting a signal having a plurality of segments of multilevel symbols arranged in frames of two fields with each field having a field sync segment and each segment having a segment sync; generating a first symbol sequence; generating a second symbol sequence that is shorter than the first symbol sequence; and combining the segment sync and the first and second symbol sequences to form a field sync segment in which the first sequence is followed by three of the second sequences, the polarity of the middle one of the three second sequences being inverted in alternate fields. - View Dependent Claims (6, 7, 8)
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9. A method of operating a receiver comprising:
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receiving a digital data signal having a plurality of segments of multilevel symbols arranged in frames of two fields with each field having a field sync segment comprising a first symbol sequence and a second symbol sequence that is shorter than the first symbol sequence and whose polarity is inverted in alternate fields, each segment having a segment sync, the method comprising; applying the field sync segment to an equalizer; and operating the equalizer in response to the applied field sync segment to cancel linear distortions characterizing the received digital data signal. - View Dependent Claims (10, 11)
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12. A method of operating a digital transmission system comprising:
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formatting a signal having a plurality of segments of multilevel symbols arranged in frames of two fields with each field having a field sync segment and each segment having a segment sync; generating a 511 pseudo-random number symbol sequence; generating three 63 pseudo-random number symbol sequences, with the middle 63 symbol sequence being inverted in polarity in alternating fields; multiplexing the 511 and three 63 pseudo-random symbol sequences to generate a field sync signal; deriving an equalizer control signal in response to at least a portion of the field sync signal. - View Dependent Claims (13, 14, 15)
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Specification