Abstract: An arrangement for reading information from a record carrier, such as in a HDD, include a read head (Rmr1), an amplifier (74) for amplifying the signal read by the read head, an equalizer (76) for equalizing the signal read by the read head, and a bit detector (80) for detecting bits in the signal read by the read head. The invention, the arrangement further comprises a DC correction unit (78) for subtracting a correction value from an input signal in response to an error signal so as to obtain a DC corrected output signal. The bit detector (80) detects a sequence of bits based in the DC corrected output signal. Further, an error signal generating unit (82,83,85) is present for generating the error signal in response to the DC corrected output signal and the sequence.

Abstract: A method and apparatus for improving baseline recovery of an MR head using a programmable AC coupling pole. The location of the pole may be adjusted to achieve the fastest recovery from a baseline shift without degrading the normal channel performance. Further, the pole may be moved during the data recovery procedure to recover from a data read error. The programmable AC coupling pole includes a circuit path carrying digital data signals read from a recording media by a magnetic head, an amplifier coupled to the circuit path for amplifying the digital data signals, and a recovery time setting device having an programmable recovery time constant associated therewith. Once a data read error has been detected by the system, the recovery time constant may be adjusted to set a recovery time for the amplifier to provide readable data signals.

Abstract: An MR head self-testing method is provided to test for instability in MR heads incorporated with a hard disk drive. A first method is carried out with the disk rotating and includes positioning the MR head over a rotating magnetic storage disk and controlling the MR head to read from erased data fields defined on the disk. This read signal is filtered and conditioned according to preprogrammed filter coefficients contained in an FIR filter to provide an exaggerated read error signal. The exaggerated read error signal is provided to a digital comparator and counter circuit for detecting and counting voltage baseline jumps that exceed preprogrammed positive and/or negative threshold values. The counted positive and negative voltage baseline jumps, which are indicative of MR head instability, are provided to an error diagnostic register for analysis. If the error diagnostic register contains single polarity voltage baseline jumps, the voltage baseline jumps may be caused by thermal asperities on the disk.