System, method and program for determining the magnetic center shift within a disk drive system

1. Field of the Invention In summary, preferred embodiments disclose a system, method, and program for determining a value for non-mechanical noise within a disk drive system. The non-mechanical noise is likely related to instability in a head which reads data from a magnetic surface within the disk drive system. First, a sample of position error signals (PES) indicating non-repeatable runouts (NRRO) is provided from read operations within the disk drive system. Spectral analysis is then performed on the provided samples to calculate non-filtered power values for the NRRO values at different frequencies. A filtered power spectrum is determined within a frequency range excluding mechanical noise. A filtered power value is calculated from the determined filtered power spectrum within the frequency range excluding mechanical noise. The calculated filtered power value may be compared against a predetermined value to determine whether to reject the disk drive system on the grounds that there is too much non-mechanical noise or noise related to instabilities and defects in the MR head.