The present disclosure provides an optical disk device capable of reproducing data recorded on a high linear density optical disk stably. The optical disk device according to the disclosure is characterized by being equipped with a recording expected waveform generation circuit which generates, at the time of recording, an expected waveform that is expected to be obtained at the time of decoding; and a recording pulse generation circuit which generates a recording pulse for driving a laser with power and a time width suitable for an amplitude value of the recording expected waveform for each sampling point of the recording expected waveform.

The present disclosure provides an optical disk device capable of reproducing data recorded on a high linear density optical disk stably. The optical disk device according to the disclosure is characterized by being equipped with a recording expected waveform generation circuit which generates, at the time of recording, an expected waveform that is expected to be obtained at the time of decoding; and a recording pulse generation circuit which generates a recording pulse for driving a laser with power and a time width suitable for an amplitude value of the recording expected waveform for each sampling point of the recording expected waveform.

A phono cartridge transmission line impedance matching system is provided. The phono cartridge transmission line impedance matching system comprises a connecting port adapted for being connected to a signal line and a ground line of a phono cartridge transmission line. A capacitance switching circuit is connected to the signal line and the ground line in a parallel fashion. The capacitance switching circuit is adapted for selectively switching between different capacitances. A plurality of resistance switching circuits, connected with each other in a serial fashion, are connected to the signal line and the ground line in a parallel fashion. Each resistance switching circuit is adapted for selectively switching between different resistances.

A repeatable runout (RRO) is accurately compensated for while moving a magnetic head radially across a disk surface. An iterative learning control algorithm is employed to determine appropriate feed-forward coefficients for an RRO compensation signal for each of a plurality of radial locations across the disk surface. The feed-forward coefficients are determined by performing multiple iterations of continuously moving the magnetic head across the disk surface along a target path while measuring a position error signal that indicates the radial error between the magnetic head and the target path. With each iteration, the iterative learning control algorithm computes new feed-forward coefficients for each of the plurality of radial locations, where the new feed-forward coefficients are selected to reduce the measured position error signal when employed to move the magnetic head along the target path.

A repeatable runout (RRO) is accurately compensated for while moving a magnetic head radially across a disk surface. An iterative learning control algorithm is employed to determine appropriate feed-forward coefficients for an RRO compensation signal for each of a plurality of radial locations across the disk surface. The feed-forward coefficients are determined by performing multiple iterations of continuously moving the magnetic head across the disk surface along a target path while measuring a position error signal that indicates the radial error between the magnetic head and the target path. With each iteration, the iterative learning control algorithm computes new feed-forward coefficients for each of the plurality of radial locations, where the new feed-forward coefficients are selected to reduce the measured position error signal when employed to move the magnetic head along the target path.

A phono cartridge transmission line impedance matching system is provided. The phono cartridge transmission line impedance matching system comprises a connecting port adapted for being connected to a signal line and a ground line of a phono cartridge transmission line. A capacitance switching circuit is connected to the signal line and the ground line in a parallel fashion. The capacitance switching circuit is adapted for selectively switching between different capacitances. A plurality of resistance switching circuits, connected with each other in a serial fashion, are connected to the signal line and the ground line in a parallel fashion. Each resistance switching circuit is adapted for selectively switching between different resistances.

A method of testing a dynamic write field of a recording head includes preparing a test magnetic medium and recording a write signal on the test magnetic medium with the write signal being set at a first write parameter and a second write parameter. An average of multiple read-back signals of the recorded write signal are captured to determine an average amplitude of the read-back signals. The recording of the write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal are repeated to determine the average amplitude of the read-back signals by fixing the first write parameter of the write signal and changing the second write parameter of the write signal until the average amplitude of the read-back signals saturates.

Method and apparatus adaptively adjusting power levels of a data transducer in a data storage device. In some embodiments, an initial power value is applied to a powered element of a transducer to write user data from a host device to a rotatable data recording medium. An exception condition is declared responsive to a measured parameter. The transducer is used to read data from an evaluation track using a range of different input power values for the powered element. A different, new power value is selected for the powered element responsive to an error rate associated with each of the range of different input power values, with the new power value being lower than the initial power value. Thereafter, the new power value is applied to the powered element during a subsequent writing of user data to the rotatable data recording medium.

During field operation of a heat-assisted magnetic recording data storage device, a laser adjustment procedure is performed. The laser adjustment procedure involves writing on a recording medium at least three tracks. If a bit error rate of a middle tracks has increased, the laser current is swept while recording test tracks to determine a new laser current that results in a minimum bit error rate. The new laser current is used for subsequent write operations.

During field operation of a heat-assisted magnetic recording data storage device, a laser adjustment procedure is performed. The laser adjustment procedure involves writing on a recording medium at least three tracks. If a bit error rate of a middle tracks has increased, the laser current is swept while recording test tracks to determine a new laser current that results in a minimum bit error rate. The new laser current is used for subsequent write operations.