Patents by Inventor Quek Leong Choo
Quek Leong Choo has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9915944Abstract: 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.Type: GrantFiled: August 17, 2011Date of Patent: March 13, 2018Assignee: SEAGATE TECHNOLOGY LLCInventors: Mathuranathan Viswanathan, Myint Ngwe, Quek Leong Choo
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Patent number: 9495987Abstract: The disclosed technology provides techniques for mitigating write-to-write bit error rate fluctuations that decrease accuracy of write precompensation (WPC) tuning. According to one implementation, such write-to-write bit error rate fluctuations are mitigated if a predetermined pattern is written at a particular radial offset from a target data track prior to testing a WPC register in association with the target data track. Selection of the particular radial offset can be performed according to an iterative offset track clean-up disclosed herein.Type: GrantFiled: May 1, 2015Date of Patent: November 15, 2016Assignee: SEAGATE TECHNOLOGY LLCInventors: Ben Niu, Lan Xia, Fong Kheon Chong, Quek Leong Choo, Song Wee Teo
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Publication number: 20160322074Abstract: The disclosed technology provides techniques for mitigating write-to-write bit error rate fluctuations that decrease accuracy of write precompensation (WPC) tuning According to one implementation, such write-to-write bit error rate fluctuations are mitigated if a predetermined pattern is written at a particular radial offset from a target data track prior to testing a WPC register in association with the target data track. Selection of the particular radial offset can be performed according to an iterative offset track clean-up disclosed herein.Type: ApplicationFiled: May 1, 2015Publication date: November 3, 2016Inventors: Ben Niu, Lan Xia, Fong Kheon Chong, Quek Leong Choo, Song Wee Teo
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Patent number: 8780679Abstract: Techniques for data recovery from a data block wherein portions of the data block are written at different off-track positions are described. For example, portions of a data block can be read separately for each on-track and off-track position in the data block; then, the separately read portions can be recombined into a recovered data block.Type: GrantFiled: July 31, 2007Date of Patent: July 15, 2014Assignee: Seagate Technology LLCInventors: Myint Maung Ngwe, Hong Li Sun, Hiau Choon Kee, Quek Leong Choo, Kian Wai Ng, Zhi Ye
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Publication number: 20130046491Abstract: 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.Type: ApplicationFiled: August 17, 2011Publication date: February 21, 2013Applicant: SEAGATE TECHNOLOGY LLCInventors: Mathuranathan Viswanathan, Myint Ngwe, Quek Leong Choo
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Publication number: 20090034380Abstract: Techniques for data recovery from a data block wherein portions of the data block are written at different off-track positions are described. For example, portions of a data block can be read separately for each on-track and off-track position in the data block; then, the separately read portions can be recombined into a recovered data block.Type: ApplicationFiled: July 31, 2007Publication date: February 5, 2009Applicant: Seagate Technology LLCInventors: Myint Maung Ngwe, Hong Li Sun, Hiau Choon Kee, Quek Leong Choo, Kian Wai Ng, Zhi Ye
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Patent number: 6920001Abstract: A method of categorizing magnitudes of thermal asperities in a read-back signal of a data storage system includes receiving the read-back signal from a location containing a thermal asperity. A peak magnitude signal is generated from the read-back signal. A threshold signal is generated using a variable threshold generator. The peak magnitude signal is compared to the threshold signal and a magnitude of the thermal asperity is categorized as a function of the comparison.Type: GrantFiled: June 12, 2003Date of Patent: July 19, 2005Assignee: Seagate Technology LLCInventors: Teng Hou Sebastian Chua, Myint Ngwe, Lan Xia, Beng Wee Quak, Quek Leong Choo
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Patent number: 6903889Abstract: A method of tuning a bias parameter for a magnetoresistive head in a data storage system includes the step of identifying, from multiple possible bias parameter values, a smallest bias parameter value for the magnetoresistive head which both maintains a bit error rate above a predetermined threshold bit error rate, and which satisfies a second criteria. The method then includes the step of setting an operational bias parameter value for the magnetoresistive head to the identified smallest bias parameter value. Also disclosed are data storage systems, or controllers which are connectable to or included with data storage systems, configured to implement the methods.Type: GrantFiled: June 11, 2003Date of Patent: June 7, 2005Assignee: Seagate TechnologyInventors: Liu Li, Quek Leong Choo, Song Wee Teo, Myint Ngwe, Beng Wee Quak
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Patent number: 6839193Abstract: A method for optimizing the read-to-write offset of a disk drive system in respect of a track is provided. In one aspect the method includes the step of determining a first read position amongst a range of test positions offset relative to the track on the basis of read signal strength. The method further includes the steps of calculating a subrange of test positions about the first read position, selecting a second read position from the subrange on the basis of bit error rates and setting the read-to-write offset as a function of the second read position. In addition a disk drive system including means for optimally setting the read-to-write offset in respect of a track is provided.Type: GrantFiled: December 11, 2001Date of Patent: January 4, 2005Assignee: Seagate Technology LLCInventors: Fong Kheon Chong, Quek Leong Choo, Myint Ngwe, Jun Wang, Kah Liang Gan
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Publication number: 20040252392Abstract: A method of categorizing magnitudes of thermal asperities in a read-back signal of a data storage system includes receiving the read-back signal from a location containing a thermal asperity. A peak magnitude signal is generated from the read-back signal. A threshold signal is generated using a variable threshold generator. The peak magnitude signal is compared to the threshold signal and a magnitude of the thermal asperity is categorized as a function of the comparison.Type: ApplicationFiled: June 12, 2003Publication date: December 16, 2004Applicant: Seagate Technology LLCInventors: Teng Hou Sebastian Chua, Myint Ngwe, Lan Xia, Beng Wee Quak, Quek Leong Choo
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Publication number: 20040252398Abstract: A method of tuning a bias parameter for a magnetoresistive head in a data storage system includes the step of identifying, from multiple possible bias parameter values, a smallest bias parameter value for the magnetoresistive head which both maintains a bit error rate above a predetermined threshold bit error rate, and which satisfies a second criteria. The method then includes the step of setting an operational bias parameter value for the magnetoresistive head to the identified smallest bias parameter value. Also disclosed are data storage systems, or controllers which are connectable to or included with data storage systems, configured to implement the methods.Type: ApplicationFiled: June 11, 2003Publication date: December 16, 2004Applicant: Seagate Technology LLCInventors: Liu Li, Quek Leong Choo, Song Wee Teo, Myint Ngwe, Beng Wee Quak
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Patent number: 6798596Abstract: A guardband portion is written on a disc surface in a disc drive. A predetermined data pattern is written on at least one data track adjacent to the guardband portion. A predetermined guardband pattern is written at a plurality of different guardband frequencies in the guardband portion. For each guardband frequency, at least one performance criterion is measured for the data track. A desired guardband pattern is written on the guardband portion of the disc surface at a guardband frequency chosen based on the measured performance criterion.Type: GrantFiled: November 27, 2001Date of Patent: September 28, 2004Assignee: Seagate Technology LLCInventors: Eng Hock Lim, Quek Leong Choo, Kok Leong Loh, Myint Ngwe, Kah Liang Gan
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Patent number: 6731442Abstract: A method is disclosed for detecting defects in a recordable medium such as a hard disc drive based on error energy. The method may include the steps of writing test data to the medium and reading back the test data. The method may also include the steps of computing an error energy based on the square of the difference between the read back data and an ideal version of the test data and comparing the error energy with an energy threshold. The method generates a defect signal when the error energy exceeds the energy threshold. The method may also be used to identify the media defect according to its error energy profile. An apparatus for detecting defects in a recordable medium is also disclosed.Type: GrantFiled: January 31, 2002Date of Patent: May 4, 2004Assignee: Seagate Technologies LLCInventors: Ming Jin, Myint Ngwe, David Loh, Quek Leong Choo, Mingyou Hu
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Patent number: 6657803Abstract: A method and apparatus are provided for reading from a storage medium to form data values. A signal is generated from a sector on the storage medium and a section of that signal is identified as having a change in amplitude. A gain multiplier is activated to multiply that section of the signal by a gain value. The gain multiplier is deactivated at the end of the section so that the remaining portion of the sector signal is not multiplied by the gain value. This results in a defect adjusted signal that is applied to a detector to detect data values.Type: GrantFiled: November 21, 2000Date of Patent: December 2, 2003Assignee: Seagate Technology LLCInventors: Khong Mau Ling, Myint Ngwe, Kah Liang Gan, Lakshmi Anantha Challa, Quek Leong Choo
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Patent number: 6549020Abstract: A method for characterizing a bearing cartridge based on a preload applied to the bearing cartridge used in a disc drive, to increase disc drive yield rates. The method begins by loading the bearing cartridge on to a test fixture and to an actuator assembly such that the actuator is rotatably attached to the base by the bearing cartridge. Then, the method includes inducing a steady swing in the actuator. Then, the method includes measuring a voltage drop that occurs across the bearing cartridge during the steady swing to characterize the preload applied to the bearing cartridge.Type: GrantFiled: February 23, 2001Date of Patent: April 15, 2003Assignee: Seagate Technology LLCInventors: Eng Hock Lim, Quek Leong Choo, Myint Ngwe, Kah Liang Gan, Beng Wee Quak
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Publication number: 20030063405Abstract: A method is disclosed for detecting defects in a recordable medium such as a hard disc drive based on error energy. The method may include the steps of writing test data to the medium and reading back the test data. The method may also include the steps of computing an error energy based on the square of the difference between the read back data and an ideal version of the test data and comparing the error energy with an energy threshold. The method generates a defect signal when the error energy exceeds the energy threshold. The method may also be used to identify the media defect according to its error energy profile. An apparatus for detecting defects in a recordable medium is also disclosed.Type: ApplicationFiled: January 31, 2002Publication date: April 3, 2003Inventors: Ming Jin, Myint Ngwe, David Loh, Quek Leong Choo, Mingyou Hu
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Publication number: 20030053236Abstract: A representation of the signal level on a data head is obtained by combining the signal level values corresponding to more than one sector of a track on a disc surface. This makes it much easier to lock on to a relatively accurate representation of the actual head signal amplitude, even in the presence of servo disturbances.Type: ApplicationFiled: May 22, 2002Publication date: March 20, 2003Inventors: David Kok Leong Loh, Victor Chew Weng Khin, Quek Leong Choo, Myint Ngwe, KahLiang Gan
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Publication number: 20030026017Abstract: A method for optimizing the read-to-write offset of a disk drive system in respect of a track is provided. In one aspect the method includes the step of determining a first read position amongst a range of test positions offset relative to the track on the basis of read signal strength. The method further includes the steps of calculating a subrange of test positions about the first read position, selecting a second read position from the subrange on the basis of bit error rates and setting the read-to-write offset as a function of the second read position. In addition a disk drive system including means for optimally setting the read-to-write offset in respect of a track is provided.Type: ApplicationFiled: December 11, 2001Publication date: February 6, 2003Inventors: Fong Kheon Chong, Quek Leong Choo, Myint Ngwe, Jun Wang, Kah Liang Gan
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Publication number: 20030011921Abstract: A guardband portion is written on a disc surface in a disc drive. A predetermined data pattern is written on at least one data track adjacent to the guardband portion. A predetermined guardband pattern is written at a plurality of different guardband frequencies in the guardband portion. For each guardband frequency, at least one performance criterion is measured for the data track. A desired guardband pattern is written on the guardband portion of the disc surface at a guardband frequency chosen based on the measured performance criterion.Type: ApplicationFiled: November 27, 2001Publication date: January 16, 2003Inventors: Eng Hock Lim, Quek Leong Choo, Kok Leong Loh, Myint Ngwe, Kah Liang Gan
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Publication number: 20030002190Abstract: A method is provided in which an optimal read gate delay duration for reading from a track of a hard disk drive is determined. The disk drive is of the type having read and write elements separated by an inter-element spacing and a platter including a plurality of radially spaced tracks. In one aspect the method comprises the steps of writing a bit pattern to a track, reading the bit pattern with each of a range of read gate delay durations, calculating a read bit error rate for each said duration and setting the optimal read gate delay to the delay duration corresponding to the lowest read bit error rate. In addition a computer program product, readable by a computer system for implementing the method is also provided.Type: ApplicationFiled: December 11, 2001Publication date: January 2, 2003Inventors: Song Wee Teo, Quek Leong Choo