Skew sensing for digital tape playback

摘要

A plural channel playback system comprising magnetic recording tape movable past a reproducing transducer head having at least one transducing element for each track is shown together with skew detecting means. At least two of the tracks are recorded with digital data signals comprising equal length data words with a parity bit, with the parity bits being simultaneously recorded along the tracks. Parity bit lock-on circuits are responsive to outputs from two tracks, which lock-on circuits generate word clock pulses in synchronization with the recorded parity bit signals. A phase detector responsive to word clock pulses from the parity bit lock-on circuits produces an error signal output proportional to the phase difference between said word clock pulse inputs thereto, which error signal is related to skew. The azimuthal position of the reproducing head relative to the recording tape is adjusted either manually or automatically to minimize the error signal.