Systems and methods for a providing a chirped current profile with an undershoot for a channel preamplifier are described. A method for writing bits in a magnetic recording disc may include applying an overshoot to a write current which is supplied to a magnetic writer of the magnetic recording disc and applying an undershoot to the write current after the overshoot is applied to at least partially de-saturate the magnetic writer. The method may also include writing a bit to the magnetic recording disc with the magnetic writer using the supplied write current. In some examples, the application of a short negative pulse after an overshoot portion of the write current waveform is delivered to the head during a write operation that writes the bit to the magnetic recording disc.

According to one embodiment, a magnetic recording and reproducing device which has a magnetic recording medium, a magnetic head, and a recording current output unit. Magnetic data is recorded on the magnetic recording medium. The magnetic head records the magnetic data on the magnetic recording medium. The recording current output unit supplies a recording current to the magnetic head so as to magnetize the magnetic head. A waveform of the recording current has a first slope for a first period to record data of first information continuously and a second slope for a following second period to switch the data to data of second information and to record the data of the second information. The first slope and the second slope are different from each other.

A computer-implemented method according to one embodiment includes performing anti-aliasing filtering on each of a plurality of signals, each signal having a frequency that is a different fraction of a frequency of a data read clock. An amplitude of each of the signals is measured after the anti-aliasing filtering. In response to the amplitudes of the signals being within a predefined range, anti-aliasing settings used during the anti-aliasing filtering are stored. In response to the amplitudes of the signals being outside the predefined range, the anti-aliasing settings are changed. A computer program product according to another embodiment includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. The program instructions are executable by a processing circuit to cause the processing circuit to perform the foregoing method.

A computer-implemented method, according to one embodiment, includes, performing anti-aliasing filtering on each of a plurality of symmetrical square wave signals, each symmetrical square wave signal having a frequency that is a different fraction of a frequency of a data read clock. The filtered symmetrical square wave signals are passed through a band pass filter. An amplitude of each of the symmetrical square wave signals is measured after the band pass filtering. In response to the amplitudes of the symmetrical square wave signals being within a predefined range, anti-aliasing settings used during the anti-aliasing filtering are stored. In response to the amplitudes of the symmetrical square wave signals being outside the predefined range, the anti-aliasing settings are changed.

A computer-implemented method, according to one embodiment, includes, performing anti-aliasing filtering on each of a plurality of symmetrical square wave signals, each symmetrical square wave signal having a frequency that is a different fraction of a frequency of a data read clock. The filtered symmetrical square wave signals are passed through a band pass filter. An amplitude of each of the symmetrical square wave signals is measured after the band pass filtering. In response to the amplitudes of the symmetrical square wave signals being within a predefined range, anti-aliasing settings used during the anti-aliasing filtering are stored. In response to the amplitudes of the symmetrical square wave signals being outside the predefined range, the anti-aliasing settings are changed.

According to one embodiment, a magnetic disk device includes a magnetic recording medium, a head including a recording magnetic pole, a spin torque oscillator provided near the recording magnetic pole, and a coil which excites the recording magnetic pole, a first current supply which supplies the coil with a first current corresponding to write data, a detector which detects a first signal corresponding to the write data, and outputs a second signal in accordance with the first signal, and a second power supply which varies, in accordance with the second signal, a second current supplied to the spin torque oscillator.

In one embodiment, a system includes one or more processors and logic integrated with and/or executable by the one or more processors. The logic is configured to cause at least one of the processors to detect positive peak amplitudes and negative peak amplitudes of an unequalized readback signal that exhibits imperfect or bi-modal waveform peaks using a peak tracking threshold module positioned at an input to an equalizer. Also, the logic is configured to cause the at least one of the processors to track the positive peak amplitudes and the negative peak amplitudes of the unequalized readback signal in a record. Moreover, the logic is configured to cause the at least one of the processors to provide, as an input to an asymmetry compensator, the record of the peak amplitudes and the negative peak amplitudes determined from the unequalized readback signal.

A method comprises creating calibration data using a first control circuitry of an apparatus, replacing the first control circuitry with a second control circuitry in the apparatus, and operating the apparatus with the second control circuitry using the calibration data. As an example, the apparatus may be a disc drive. The second control circuitry may be substantially similar to the first control circuitry such that calibration measurements using the first control circuitry are applicable to the second control circuitry. The first control circuitry may be included in a circuit board that is replaced with a second circuit board including the second control circuitry. In an exemplary embodiment, the second circuit board may include different and/or additional components relative to the first circuit board, such as integrated video inputs and/or video control circuitry.

A method comprises creating calibration data using a first control circuitry of an apparatus, replacing the first control circuitry with a second control circuitry in the apparatus, and operating the apparatus with the second control circuitry using the calibration data. As an example, the apparatus may be a disc drive. The second control circuitry may be substantially similar to the first control circuitry such that calibration measurements using the first control circuitry are applicable to the second control circuitry. The first control circuitry may be included in a circuit board that is replaced with a second circuit board including the second control circuitry. In an exemplary embodiment, the second circuit board may include different and/or additional components relative to the first circuit board, such as integrated video inputs and/or video control circuitry.

First and second signal patterns are used to write corresponding portions of first and second adjacent tracks to a magnetic storage medium. A characteristic of the first signal pattern is changed based on the second signal pattern, the changing of the characteristic reducing an adjacent track interference affecting the second track.