Abstract: A method and system for providing simultaneous localization of defects in both the time and frequency domain. A high frequency repeating pattern is written on media, and the pattern is read to generate a readback signal, which is converted into ADC samples. The ADC samples are analyzed, in-line, to determine the type of wavelet, level of decomposition, and threshold level for a wavelet transform of the particular readback signal. The wavelet transform provides details and/or approximations (wavelet coefficients) that are analyzed to determine the type, location, and duration of any identified defects. Any noise in the details and/or approximations (wavelet coefficients) is removed by a wavelet based denoising operation. Flags indicating the type, location, and duration of any defects are generated so that the defects may be mapped.

Abstract: A data sector is read using two or more passes of a read head over a recording medium. Each of the passes corresponds to a different cross-track offset, each of the data sectors being divided into two or more blocks. For each of the blocks, data is selected from one of the passes that read the block with a higher quality than other passes that read the block. The selected data from each of the blocks to is combined to form recovered data of the data sector.

Abstract: Data is read from a track of a magnetic recording medium via multiple read transducers located at different positions on a read head. The multiple read transducers are substantially positioned over the track when reading the track. The multiple read transducers have different design characteristics manifesting in differences in at least one of magnetic and electrical behavior of the multiple read transducers. One or more signals originating from the multiple read transducers are combined to assist in decoding the data.

Abstract: An exemplary method for selecting data density values (e.g., bits per inch) and track density values (e.g., tracks per inch) for magnetic recording media having variable bit aspect ratios comprises obtaining a plurality of data density values and a plurality of track density values as a function of a corresponding plurality of bit error rates; determining a data density/track density correlation between the plurality of data density values and the plurality of track density values for at least one Sector Error Rate; and determining a data density capability value and a track density capability value that provides an areal density capability value that satisfies one or more predefined criteria (e.g., a substantially maximum areal density capability value) using the data density/track density correlation.

Abstract: Methods including determining a distribution of a position error signal (PES) of a magnetoresistive head by obtaining PES data from a servo controller associated with the magnetoresistive head; determining an encroachment function of a storage disc; and determining a track density of the storage disc by considering both the PES distribution and the encroachment function.

Abstract: A method for detecting a contact event between a transducer and a recording medium is disclosed. The method includes positioning a transducer with respect to a recording medium, where the transducer includes a writer, a reader, a heater, and a thermally responsive sensor. The method further includes applying power to the heater to establish a fly height of the transducer; supplying a bias current through the thermally responsive sensor to generate a bias signal; measuring a root mean square (RMS) voltage VRMS of the thermally responsive sensor based on the bias signal; determining a threshold voltage VT; and detecting a contact event between the transducer and the medium based on VRMS being greater than VT.

Abstract: A method for detecting a contact event between a transducer and a recording medium is disclosed. The method includes positioning a transducer with respect to a recording medium, where the transducer includes a writer, a reader, a heater, and a thermally responsive sensor. The method further includes applying power to the heater to establish a fly height of the transducer; supplying a bias current through the thermally responsive sensor to generate a bias signal; measuring a root mean square (RMS) voltage VRMS of the thermally responsive sensor based on the bias signal; determining a threshold voltage VT; and detecting a contact event between the transducer and the medium based on VRMS being greater than VT.

Abstract: A method and system for providing simultaneous localization of defects in both the time and frequency domain. A high frequency repeating pattern is written on media, and the pattern is read to generate a readback signal, which is converted into ADC samples. The ADC samples are analyzed, in-line, to determine the type of wavelet, level of decomposition, and threshold level for a wavelet transform of the particular readback signal. The wavelet transform provides details and/or approximations (wavelet coefficients) that are analyzed to determine the type, location, and duration of any identified defects. Any noise in the details and/or approximations (wavelet coefficients) is removed by a wavelet based denoising operation. Flags indicating the type, location, and duration of any defects are generated so that the defects may be mapped.

Abstract: The disclosure is related to pulse width modulating a power signal to a heat resistive element of a transducer. The power signal may be a power output signal of preamplifier. The power signal may be provided to a heat resistive element in a transducer that is operable to read data from or write data to a data storage medium. The pulse width modulated power signal can allow for controlling the heating of the heat resistive element based on a thermal time constant of the heat resistive element and based on adjustable components of the pulse width modulated power signal.

Abstract: In general, this disclosure describes read recovery techniques for data storage devices that use soft information associated with multiple read operations to detect data. Specifically, the read recovery techniques comprise computing soft information for each bit detected during a first read operation of a data storage medium, computing soft information for each bit detected during a second read operation of the data storage medium and averaging the soft information computed during the first and second read operations to determine the value of each of the bits.

Abstract: The disclosure is related to pulse width modulating a power signal to a heat resistive element of a transducer. The power signal may be a power output signal of preamplifier. The power signal may be provided to a heat resistive element in a transducer that is operable to read data from or write data to a data storage medium. The pulse width modulated power signal can allow for controlling the heating of the heat resistive element based on a thermal time constant of the heat resistive element and based on adjustable components of the pulse width modulated power signal.

Abstract: A buffer random access memory has a first portion reserved for a defect table and a second portion reserved for data caching. A method of managing the buffer random access memory includes determining actual memory space of the first portion which is occupied by the defect table. This identifies unused memory space of the first portion of the buffer random access memory. The method then includes reallocating the unused memory space of the first portion of the buffer random access memory for use in data caching. Controllers and mass storage devices which implement the method are also provided.

Abstract: A method for monitoring a data storage medium is provided in which a virtual head fly profile is measured. In addition, a data storage device for implementing the monitoring method is provided.

Abstract: A data word is error correction encoded to provide a worst case codeword without bit transitions between worst case codeword bits. A modulation bit is calculated as a function of the worst case codeword. The modulation bit has a bit polarity opposite a bit polarity of the worst case codeword bits. The worst case codeword bits are added with the modulation bit to form a modulated code word.

Abstract: A method and apparatus for selectively terminating turbo equalization is disclosed. At least two iterations of turbo equalization are performed. The number of errors corrected between the first iteration and the second iteration are calculated. In one embodiment, if the sign of corresponding bits in the data block is different between the two iterations, an error was corrected. If the number of errors corrected is greater than a stopping value, a subsequent iteration of turbo equalization is performed. If the number of errors corrected is less than or equal to the stopping value, then associated values for the data are output and the turbo equalization is terminated.

Abstract: In general, this disclosure describes read recovery techniques for data storage devices that use soft information associated with multiple read operations to detect data. Specifically, the read recovery techniques comprise computing soft information for each bit detected during a first read operation of a data storage medium, computing soft information for each bit detected during a second read operation of the data storage medium and averaging the soft information computed during the first and second read operations to determine the value of each of the bits.

Abstract: A data word is error correction encoded to provide a worst case codeword without bit transitions between worst case codeword bits. A modulation bit is calculated as a function of the worst case codeword. The modulation bit has a bit polarity opposite a bit polarity of the worst case codeword bits. The worst case codeword bits are added with the modulation bit to form a modulated code word.

Abstract: A system and method for performing read retry operations with respect to an erroneously read data sector is disclosed. The system and method use estimates of bit error rates determined during previous attempts to read data from the sector to determine an optimal distance and direction to move a read transducer for a subsequent read retry of the erroneously data sector.

Abstract: Methods and associated apparatus to reduce electrical power consumption in an information channel may include identifying times at which to restore power to elements in the information channel, and restoring power to the elements at the identified times. Times for each element are identified based on a recovery time for that element to reach a sufficiently stable operating point before a transition to an active mode of operation. By maximizing the length of time individual elements may stay in the reduced power mode, power savings may be maximized without negatively affecting information channel performance.

Abstract: A motion control system has an enclosed assembly that encloses moving parts. A controller controls a motion of the moving parts and has an inhibit input that inhibits the motion. A sensor provides sensor outputs that depend on an assembly temperature and an assembly humidity in the enclosed assembly. A circuit provides a condensing condition output as a function of the sensor outputs. The condensing condition output couples to the inhibit input to inhibit the motion as a function of the sensor outputs.