A playback device (measurement device) in a record playback system including a record player and the playback device measures a frequency characteristic of each of a plurality of input signals which are input from the record player to the playback device when a plurality of test signals for measuring a characteristic of the record playback system are played back by the record player, the plurality of test signals being recorded on a phonograph record, the plurality of input signals corresponding to the plurality of test signals recorded; calculates a measurement error between the frequency characteristic of each of the plurality of input signals measured and a predetermined frequency characteristic; selects a frequency characteristic of which the measurement error is smallest from among the frequency characteristics of the plurality of input signals, as a measurement result of the record playback system; and outputs the measurement result selected.

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The one or more processing devices are configured to: output a multi-rate excitation to at least one multi-rate notch filter of the actuator mechanism control system; detect a frequency response of the actuator mechanism in response to the multi-rate excitation; and calibrate the at least one multi-rate notch filter of the actuator mechanism control system, based at least in part on the detected frequency response of the actuator mechanism.

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The one or more processing devices are configured to: output a multi-rate excitation to at least one multi-rate notch filter of the actuator mechanism control system; detect a frequency response of the actuator mechanism in response to the multi-rate excitation; and calibrate the at least one multi-rate notch filter of the actuator mechanism control system, based at least in part on the detected frequency response of the actuator mechanism.

The present disclosure describes aspects of codeword interleaving over magnetic media surfaces. In some aspects, segments of a codeword are spread or interleaved across multiple surfaces of magnetic storage media. Data for one or more codewords may be received by a read/write channel and, for each codeword, a respective index is selected, received, or generated. The index may indicate which sector partitions of the multiple surfaces that segments of one of the codewords are to be written. The data of the codewords can be segmented and then arranged in an interleaver based on the respective index to which the codeword corresponds. The codeword segments are written from the interleaver to sectors of the multiple surfaces of the magnetic media. By so doing, codewords may be spread across multiple surfaces, such that a loss of a portion of a segment track does not prevent readback and decoding of the codewords.