Nonlinear distortion in helical-scan tape recorders

Nonlinear distortion in high-frequency high-density tape recording is investigated. Experiments were conducted on a helical-scan tape transport at a single-channel data rate of 150 Mb/s using MIG (metal-in-gap) heads and metal particle tape. Nonlinear distortion was characterized by extracting the echo from the dipulse response of a pseudorandom sequence recording. It is found that a transition is sharpened and shifted earlier by the immediately preceding transition. A precompensation scheme using the combination of record current overshoot and zero-crossing delay can eliminate almost all the nonlinear distortion. Bit-error-rate improvement was demonstrated in recordings using this precompensation scheme.>