Robust metric computation of longitudinal position (LPOS) data symbol detection

A computer program product comprising a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising:

• computer readable program code configured to receive a plurality of servo pulses read from at least one defined servo track of a magnetic tape while the magnetic tape is moving past a magnetic head, wherein the plurality of servo pulses are from one or more servo bursts, the one or more servo bursts representing at least an encoded data symbol;
• computer readable program code configured to provide a sequence of samples of the readback servo signal;
• computer readable program code configured to compute a correlation signal between the sequence and a reference waveform;
• computer readable program code configured to provide a reference timing model comprising one or more interpolation instants, wherein the correlation signal determined at each interpolation instant yields a detection metric for one data symbol;
• computer readable program code configured to interpolate the correlation signal at the interpolation instants and compute a longitudinal position (LPOS) detection metric according to the interpolated correlation signal samples;
• and
• computer readable program code configured to decode the encoded data symbol of the one or more servo bursts using the computed LPOS detection metric and estimate a reliability of the decoded data symbol of the one or more servo bursts.

A method, comprising:

• reading a plurality of servo pulses from one or more servo bursts of a servo track while a magnetic tape is moving past a magnetic head, wherein the one or more servo bursts represent at least an encoded data symbol;
• providing a sequence of samples of the readback servo signal;
• computing a correlation signal between the sequence and a reference waveform;
• providing a reference timing model comprising one or more interpolation instants, wherein the correlation signal determined at each interpolation instant yields a detection metric for one data symbol;
• interpolating the correlation signal at the interpolation instants and computing a longitudinal position (LPOS) detection metric according to the interpolated correlation signal samples;
• decoding the encoded data symbol of the one or more servo bursts using the computed LPOS detection metric;
• and
• estimating a reliability of the decoded data symbol of the one or more servo bursts,
• wherein the interpolated servo signal has about a constant data sample rate per unit length of the magnetic tape,
• wherein the encoded data symbol represented by the one or more servo bursts corresponds to either a binary “zero” data symbol or a binary “one” data symbol, and
• wherein from six to eighteen coefficients of the reference waveform are used to compute the correlation signal between the sequence and the reference waveform.