Circuit and method for sync detection and protection

A sync detecting and protecting circuit for use in a reproducing apparatus of a digital video cassette recorder including demodulating means for reproducing and demodulating data sequentially recorded on a plurality of areas on a digital tape having an SD recording format, error correction decoding means for error-correction decoding the data output from said demodulating means, and data expanding means for expanding said error-correction decoded data, said sync detecting and protecting circuit comprising:

• run-up pattern detecting means for detecting a run-up pattern of the digital data output from said demodulating means, and for generating a corresponding area signal;
• sync pattern detecting means for detecting a sync pattern from data demodulated in said demodulating means, for comparing said detected sync pattern with a predetermined sync pattern, and for outputting a sync detection signal;
• ID separating means for separating an ID following said sync pattern detected in said sync pattern detecting means, for comparing said separated ID with an ID of at least one of a previous track and sync block, and for outputting an ID comparing signal;
• pseudo-sync control signal generating means for outputting a sync control signal based on said sync detection signal and said ID comparing signal, for generating a pseudo-sync control signal if an error is detected in said detected sync pattern, and for generating a sync and ID area signal based on said sync detection signal;
• and
• data selecting means for removing the sync pattern and ID of digital data output through said run-up pattern detecting means according to said sync and ID area signal, and for outputting said sync-and-ID-removed data to said error correction decoding means.

A sync detecting and protecting method for use in a reproducing apparatus for reproducing digital data from a recording medium in which a plurality of areas for sequentially recording said digital data are arranged in a plurality of tracks, wherein each area comprises a plurality of sync blocks and a pre-amble pattern, said sync detecting and protecting method comprising:

• (a) detecting a pre-amble pattern of said digital data received from said recording medium and generating a corresponding area signal;
• (b) detecting a sync pattern of said received digital data, comparing said detected sync pattern with a predetermined sync pattern, and generating a sync detection signal;
• (c) separating an ID code following said sync pattern detected in step (b), comparing said separated ID code with an ID of at least one of a previous track and sync block, and generating an ID comparison signals;
• (d) generating a sync control signal based on said sync detection signal, and generating a pseudo-sync control signal if an error is found in said detected sync pattern.