Tape-recorded signal recovery method and apparatus

Abstract

A method and apparatus for recovering analog signal information from a multiple-track information storage medium such as a magnetic tape is based upon time base error correction of a frequency modulated carrier signal. In one embodiment, the phase difference of a pair of pilot signals recorded on tracks adjacent a data track is compared by a sampling and pulse counting technique to eventually produce a trigger signal for a phase-locked oscillator. The output of the phase-locked oscillator is employed to sample and measure the period of the input data signal. The period values are written as digital values into a digital first-in first-out buffer memory. A stable clock is used to read out the contents of the buffer memory which are thereafter converted to a pulse rate modulated pulse train. The pulse train is converted to a useable analog signal by a pulse rate to frequency converter. In other embodiments, the phase error between the pilot signals is compared with a stable reference from which a skew error signal is derived to which the phase-locked oscillator is locked. In still other embodiments, a pilot signal is derived from the data track and employed to synchronize the sampling process to the rate of data input.

Dependencies are inferred from the claim text.