An apparatus can include a circuit configured to process an input signal using a set of channel parameters. The circuit can produce, using a first adaptation algorithm, a first set of channel parameters for use by the circuit as the set of channel parameters in processing the input signal. The circuit can further approximate a second set of channel parameters of a second adaptation algorithm for use by the circuit as the set of channel parameters in processing the input signal based on the first set of channel parameters and a relationship between a third set of channel parameters generated using the first adaptation algorithm and a fourth set of channel parameters generated using the second adaptation algorithm. In addition, the circuit can perform the processing of the input signal using the second set of channel parameters as the set of channel parameters.

Zone self-servo write (SSW) technology is disclosed that leverages two clock signals synchronized in parallel to transition between zones to write servo patterns at different frequencies while minimizing error rate despite the different frequencies. Two separate clock signals (clocks) are used to locate and lock to different reference spirals. By updating both clocks in parallel instead of in series, error rate for writing while stepping up frequency across zones is reduced.

An apparatus may include a circuit configured to receive a first phase control value of a phase control value signal, generate a first phase interpolator control signal value of a phase interpolator control signal and generate a first digital interpolator control signal value of a digital interpolator control signal. The apparatus may further be configured to phase interpolate a clock signal based on the first phase interpolator control signal value to produce a phase shifted clock signal and digitally interpolate a digital sample based on the first digital interpolator signal value to produce a phase shifted digital sample having an effective phase based on the first phase control value, the digital sample generated using the phase shifted clock signal as a sample clock.

Systems and methods are disclosed for head delay calibration and tracking multi-sensor magnetic recording (MSMR) systems. In certain embodiments, an apparatus may comprise a first reader and a second reader configured to simultaneously read from a single track of a data storage medium, the first reader offset from the second reader so that the first reader and the second reader detect a same signal pattern offset in time. The apparatus may further comprise a circuit configured to determine a relative offset between the first reader and the second reader, including setting a fixed delay for a first signal from the first reader, setting a second delay for a second signal from the second reader, and adjusting the second delay to align the second signal to the first signal using a timing loop, with the first signal used as a reference signal.

Systems and methods are disclosed for full utilization of a data path's dynamic range. In certain embodiments, an apparatus may comprise a circuit including a first filter to digitally filter and output a first signal, a second filter to digitally filter and output a second signal, a summing node, and a first adaptation circuit. The summing node combine the first signal and the second signal to generate a combined signal at a summing node output. The first adaptation circuit may be configured to receive the combined signal, and filter the first signal and the second signal to set a dynamic amplitude range of the combined signal at the summing node output by modifying a first coefficient of the first filter and a second coefficient of the second filter based on the combined signal.

An apparatus may include a circuit configured to receive first and second samples of an underlying data from respective first and second sample periods and which correspond to respective first and second sensors, a phase control value may have first and second values during respective first and second sample periods. The phase control value may be a control value for a sample clock signal. The circuit may also determine a difference in the phase control value between the first value and the second value. The circuit may then digitally interpolate the first and second samples to produce a phase shifted first and second samples where the digital interpolation of at least one of the first and second samples mat be at least in part based on the difference in the phase control value to compensate for a phase misalignment between the first sample and the second sample.

Systems and methods are disclosed for full utilization of a data path's dynamic range. In certain embodiments, an apparatus may comprise a circuit including a first filter to digitally filter and output a first signal, a second filter to digitally filter and output a second signal, a summing node, and a first adaptation circuit. The summing node combine the first signal and the second signal to generate a combined signal at a summing node output. The first adaptation circuit may be configured to receive the combined signal, and filter the first signal and the second signal to set a dynamic amplitude range of the combined signal at the summing node output by modifying a first coefficient of the first filter and a second coefficient of the second filter based on the combined signal.

An apparatus may include a circuit configured to process at least one input signal using a set of channel parameters. The circuit may adapt, using a regularized adaptation algorithm, a first set of channel parameters for use by the circuit as the set of channel parameters in processing the at least one input signal, the regularized adaptation algorithm penalizing deviations by the first set of channel parameters from a corresponding predetermined second set of channel parameters. The circuit may then perform the processing of the at least one input signal using the first set of channel parameters as the set of channel parameters.

Systems and methods are disclosed for applying multi-stage multiple input single output (MISO) circuits for fast adaptation. An apparatus may comprise a first reader and a second reader configured to simultaneously read from a single track of a data storage medium, a MISO circuit. The MISO circuit may include a first stage filter having a first number of taps and configured to filter signal samples received from the first reader and the second reader and produce first filtered samples. The MISO circuit may also include a second stage filter having a second number of taps greater than the first number, and be configured to receive the first filtered samples corresponding to the first reader and the second reader from the first filter stage, filter the first filtered samples to produce second filtered samples, and combine the second filtered samples to produce a combined sample output.

An apparatus may include a first and second servo channels configured to output first and second position information to first and second writers, respectively, via a shared write path such that the first and second writers write first and second position information to first and second magnetic recording medium surfaces, respectively. In addition, the apparatus may include a controller configured to control the shared write path such that write access is changed between the first servo channel and second servo channel a plurality of times during a revolution of the first magnetic recording medium surface and second magnetic recording medium surface.