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 such 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.

An apparatus may include a circuit configured to generate, by an analog to digital converter (ADC), one or more ADC samples based on an input signal. The circuit may be further configured to generate a first estimated signal using a first channel pulse response estimation with a gain constraint based on the one or more ADC samples and generate a second estimated signal using a second channel pulse response estimation with a phase constraint based on the one or more ADC samples.

In some embodiments, a method includes receiving, at a device, digital audio content to be converted by a digital-to-analog converter to produce analog audio content. The digital audio content has at least one audible frequency. The method also includes selecting, at the device, a first signal and a second signal to output with the analog audio content. The first signal has an inaudible carrier frequency and a bandwidth, and the second signal also has an inaudible carrier frequency and a bandwidth. A difference between the first signal and the second signal is an undesired audible signal. The method further includes outputting, from the device, the analog audio content, the first signal and the second signal, such that when the analog audio content is detected by a recording device the undesired audible signal is detected with the analog audio content.

A signal conversion device includes a first converting section configured to convert a clock signal input through a first signal line, a data signal input through a second signal line, and a control signal input through a third signal line, into pulse signals including a first pulse train and a second pulse train; and a transmitting section configured to transmit the first pulse train through a fourth signal line and the second pulse train through a fifth signal line, wherein the control signal is a signal that, through a level transition, causes a control target device to switch between an active state and an inactive state, and wherein the first converting section is configured to put successive pulses into at least one of the first pulse train and the second pulse train in response to the level transition of the control signal.

A data storage device is disclosed comprising a disk, a head for accessing the disk, and a sensor for generating an alternating sensor signal. The sensor is disconnected from an input of a sensing circuit and while the sensor is disconnected an alternating calibration signal is injected into the input of the sensing circuit, wherein the alternating calibration signal comprises a predetermined offset and amplitude. A response of the sensing circuit to the alternating calibration signal is evaluated to detect at least one of an offset and a gain of the sensing circuit.

An optical disc apparatus includes a synchronizer that generates a reproduction clock signal synchronized with a reproduction signal of information recorded in an optical disc medium, and generates a digital reproduction signal synchronized with the reproduction clock signal, an adaptive equalizer that generates a post-adaptive-equalization digital reproduction signal, and a maximum likelihood decoder that performs maximum likelihood decoding of the post-adaptive-equalization digital reproduction signal to generate a binary signal. The apparatus also includes an expected waveform generator that generates an expected waveform from the binary signal, a phase-advance waveform generator that generates a phase-advance waveform, a phase-delay waveform generator that generates a phase-delay waveform, and a metric detector that detects a phase error. In the optical disc apparatus, the synchronizer controls the phase of the digital reproduction signal using the phase error.

A system for compensating for heat induced transient phase shift in a heat assisted magnetic recording system. A heat assisted magnetic data recording system includes a near field thermal transducer that locally heats the media during writing. The thermal transducer, when activated, results in a change in size of a magnetic transition written to the magnetic media. This change in size of the thermal transition results in a transient phase shift of the data recorded on the magnetic media. The system includes circuitry for predetermining an anticipated amount of transient phase shift and adjusting a subsequent read signal to compensate for the known transient phase shift, thereby eliminating signal errors resulting from the transient phase shift.

Systems and methods for providing an output signal based at least in part upon an input signal and a clock signal in a manner in which jitter is avoided or diminished, including for example a digital-to-analog converter (DAC), are disclosed herein. In one example embodiment, such a system includes an output signal generating component, a first component having a first switch and a variable characteristic, and a plurality of second components each having a respective additional switch and a respective fixed characteristic. A value of the variable characteristic is set at least in part based upon input and clock signals so that, when the variable characteristic influences at least indirectly the generating of the output signal by the output signal generating component, the output signal attains a first level that at least indirectly depends upon a phase of the clock signal relative to the input signal.

A method for synchronizing audio playback by the audio playback devices of a group with at least two audio playback devices, where the group is part of a larger zone of audio playback devices, and where one audio playback device of the zone is a master audio playback device that distributes audio data to other audio playback devices of the zone. An audio play command is received from the master audio playback device at one audio playback device of the group and in response, an audio control command is transmitted from the one audio playback device of the group to at least one other audio playback device of the group.

The present disclosure provides a signal conversion device including: a first converting section configured to convert a clock signal input through a first signal line, a data signal input through a second signal line, and a control signal input through a third signal line, into pulse signals including a first pulse train and a second pulse train; and a transmitting section configured to transmit the first pulse train through a fourth signal line and the second pulse train through a fifth signal line, wherein the control signal is a signal that, through a level transition, causes a control target device to switch between an active state and an inactive state, and wherein the first converting section is configured to put successive pulses into at least one of the first pulse train and the second pulse train in response to the level transition of the control signal.