# US 2015/0146509 A1 · Quadrature track error signal for optical recording media and devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0146509 A1 - Document ID: US20150146509A1 - Status: Published application - Kind: A1 - Application number: 14/090,240 - Filed: 2013-11-26 - Published: 2015-05-28 - Earliest claimed: 2013-11-26 - Assignees: Oracle International Corporation - Applicants: Oracle International Corporation - Inventors: FARAMARZ MAHNAD - Web page: https://patentgrep.com/patent/US20150146509A1 ## CPC - G11B 7/08505: {Methods for track change, selection or preliminary positioning by moving the head} - G11B 7/095: specially adapted for discs, e.g. for compensation of eccentricity or wobble - G11B 7/0053: {Reproducing non-user data, e.g. wobbled address, prepits, BCA} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract A method for providing tracking error signals in an optical data storage system includes a step of receiving a wobble signal having a first frequency from the wobble detection system. The wobble detection system includes an optical pick up unit that detects positions of the head relative to lands and grooves. Characteristically, the wobble signal is amplitude modulated for positions intermediate between the land and the groove. The method further includes a step of receiving a primary tracking error signal from the wobble detection system. The wobble signal is multiplied with a synchronous signal to about a product signal. The product signal is positive for a first direction of motion and negative for a second direction of motion that is opposite that of the first direction. The product signal is integrated to obtain a quadrature track error signal. ## Claims ### Claim 1 A method for providing tracking error signals in an optical digital storage system, the optical digital storage system including a transducer head and a wobble detection system, the method comprising: receiving a wobble signal having a first frequency from the wobble detection system, the wobble detection system including an optical pick up unit that detects positions of the transducer head relative to lands and grooves in an optical recording medium, the wobble signal for the optical pick up unit centered on a land being 180 degrees out of phase with the wobble signal for the optical pick up unit centered on a groove, the wobble signal being amplitude modulated for positions intermediate between the land and the groove; receiving a primary tracking error signal from the wobble detection system; multiplying the wobble signal with a synchronous signal to produce a product signal, the product signal being positive for a first direction of motion and negative for a second direction of motion that is opposite that of the first direction; and integrating the product signal to obtain a quadrature track error signal, the quadrature track error signal being 90 degrees out of phase with the primary track error signal, the quadrature track error signal and the track error signal in combination providing direction information about movement of the transducer head across data tracks. ### Claim 2 (depends on 1) The method of claim 1 wherein the quadrature track error signal and the track error signal each independently include an oscillating pattern as the transducer head moves across tracks. ### Claim 3 (depends on 1) The method of claim 1 wherein the quadrature track error signal leads the track error signal for the first direction of motion. ### Claim 4 (depends on 1) The method of claim 1 wherein the track error signal leads the quadrature track error signal for the second direction of motion. ### Claim 5 (depends on 1) The method of claim 1 wherein the quadrature track error signal changes such that the product signal is positive for the first direction of motion and negative for the second direction of motion that is opposite that of the first direction. ### Claim 6 (depends on 1) The method of claim 1 wherein the quadrature track error signal and the track error signal are each independently approximated by a sinusoidal function as the transducer head moves across tracks. ### Claim 7 (depends on 1) The method of claim 1 wherein the track error signal includes a first set of regions that are approximated by linear functions. ### Claim 8 (depends on 7) The method of claim 7 wherein the quadrature track error signal includes a second set of regions that are approximated by linear functions. ### Claim 9 (depends on 8) The method of claim 8 wherein the first set of regions that are approximated by linear functions and the second set of regions that are approximated by linear functions include non-overlapping portions with respect to displacement of the transducer head from a land or groove. ### Claim 10 (depends on 9) The method of claim of claim 9 wherein the first set of regions that are approximated by linear functions and the second set of regions that are approximated by linear functions provide complete linearization of the motion of the transducer head across the data tracks. ### Claim 11 An apparatus for providing tracking error signals in an optical storage system, the apparatus comprising: a transducer head; a wobble detection system including an optical pick up unit positioned in the transducer head in an optical recording medium, the wobble detection system detecting positions of the transducer head relative to lands and grooves, the wobble detection system providing a wobble signal having a first frequency, the wobble signal for a land being 180 degrees out of phase with the wobble signal for a groove, the wobble signal being amplitude modulated for positions intermediate between the land and the groove; a synchronous multiplier that multiplies the wobble signal with a square wave signal having the first frequency to provide a product signal, the product signal being positive for a first direction of motion and negative for a second direction of motion that is opposite that of the first direction; and an integrator that integrates the product signal to obtain a quadrature track error signal, the quadrature track error signal being 90 degrees out of phase with the track error signal, the quadrature track error signal and the track error signal in combination providing direction information about movement of the transducer head across data tracks. ### Claim 12 (depends on 11) The apparatus of claim 11 further including a phase lock loop that ensures that the square wave signal is in phase with the wobble signal. ### Claim 13 (depends on 11) The apparatus of claim 11 wherein the quadrature track error signal and the track error signal each independently include an oscillating pattern. ### Claim 14 (depends on 11) The apparatus of claim 11 wherein the quadrature track error signal leads the track error signal for the first direction of motion and wherein the quadrature track error signal lags the track error signal for the second direction of motion. ### Claim 15 (depends on 11) The apparatus of claim 11 wherein the quadrature track error signal shows a discontinuity for a change in the direction of motion of the transducer head. ### Claim 16 (depends on 11) The apparatus of claim 11 wherein the quadrature track error signal and the track error signal are each independently approximated by a sinusoidal function. ### Claim 17 (depends on 11) The apparatus of claim 11 wherein the track error signal includes a first set of regions that are approximated by linear functions and the quadrature track error signal includes a second set of regions that are approximated by linear functions. ### Claim 18 (depends on 17) The apparatus of claim 17 wherein the first set of regions that are approximated by linear functions and the second set of regions that are approximated by linear functions include non-overlapping portions with respect to displacement of the transducer head from a land or groove. ### Claim 19 (depends on 18) The apparatus of claim 18 wherein the first set of regions that are approximated by linear functions and the second set of regions that are approximated by linear functions provide complete linearization of the motion of the transducer head across the data tracks.