Track-curvature detection using clock phase shift in azimuth recording
AssigneeAmpex Corporation
InventorsKurt F. Hallamasek, Keith A. Kambies, George R. Varian
Life of this patent
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Abstract
A servomechanism for controlling the position of a magnetic-tape playback head (16) with respect to a track (24) of digital data on a magnetic tape (22) positions the head by reference to an error signal that error-signal-generation circuitry (FIG. 10). generates. Sample-clock signals obtained from simultaneously read azimuth-recorded data tracks clock respective frequency dividers (52 and 54), and a phase detector 56 generates the error signal by comparing the frequency dividers' outputs.
Claims8
A magnetic-tape player comprising:
- A) a reading mechanism forming at least first and second head gaps and generating first and second head signals representative of the contents of respective magnetic-tape tracks simultaneously passing adjacent to the first and second head gaps, the first and second head gaps forming different angles with respect to the direction of relative motion between the gaps and the magnetic tape;
- B) first and second clock-recovery circuits that receive the first and second head signals, respectively, and generate therefrom first and second clock signals that represent the bit timing of data read from the magnetic tape;
- C) curvature-error-detection circuitry that responds to the first and second clock signals by generating a curvature-error signal indicative of the timing relationship between the two clock signals and thereby representing curvature error;
- and
- D) a head-position control system that positions the first and second head gaps in accordance with the curvature-error signal.
For playing magnetic tape supplied thereto, a magnetic-tape player comprising:
- A) a reading mechanism that forms at least one head gap and alternately:
- i) positions the head gap during read intervals thereof to read respective magnetic-tape tracks on the magnetic tape and generate signals representative of those tracks' contents;
- and
- ii) so spaces the head gap from the magnetic tape in mute intervals thereof that the gap is incapable of reading those tracks' contents;
- B) curvature-error-detection circuitry for detecting the error in the head gap's positioning over successive tracks during respective read intervals and generating a curvature-error signal indicative of the error thus detected;
- and
- C) a head-position control system that responds to the curvature-error signal by positioning the head gap during at least a portion of at least some of the read intervals in accordance with the curvature error detected by the curvature-error-detection circuitry during previous read intervals and by positioning the head gap during at least a portion of at least some of the mute intervals in accordance with curvature errors extrapolated from the curvature errors detected by the curvature-error-detection circuitry during previous read intervals.
Dependencies are inferred from the claim text.