# US 6,298,101 B1 · Method and apparatus for accurately aligning a series of detection windows with a synchronization pattern in a data storage device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,298,101 B1 - Document ID: US6298101B1 - Status: Granted - Kind: B1 - Application number: 09/222,509 - Filed: 1998-12-29 - Granted: 2001-10-02 - Earliest claimed: 1998-12-29 - Assignees: Adaptec, Inc. - Inventors: Lance Robert Carlson - Web page: https://patentgrep.com/patent/US6298101B1 ## CPC - G11B 20/1419: {to or from biphase level coding, i.e. to or from codes where a one is coded as a transition from a high to a low level during the middle of a bit cell and a zero is encoded as a transition from a low to a high level during the middle of a bit cell or vice versa, e.g. split phase code, Manchester code conversion to or from biphase space or mark coding, i.e. to or from codes where there is a transition at the beginning of every bit cell and a one has no second transition and a zero has a second transition one half of a bit period later or vice versa, e.g. double frequency code, FM code} - G11B 27/3027: {used signal is digitally coded} - H04L 7/04: Speed or phase control by synchronisation signals {(H04L7/0075 takes precedence)} - H04L 7/08: the synchronisation signals recurring cyclically - 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) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An invention for more accurately initiating the generation of detection windows for detecting data within a stream of data pulses is disclosed. A high frequency clock, typically operating at rate corresponding to a multiple of the nominal clock rate (e.g., two or three times, is used for a portion of a decoder system. In one embodiment, a down counter and a detection window generation component of the decoder system are clocked at the higher rate, while the remaining elements are clocked at the nominal clock rate. In this manner, the detection windows are more accurately initiated, while the remaining portions of the decoder system do not require the extra expense imposed of operating at the higher clock rate. Using the present invention, synchronization delay is minimized and detection windows are more accurately aligned with data pulses which reduces the error rate and improves performance of the decoder system. ## Claims ### Claim 1 A system for decoding data values within a stream of data, the system being clocked at both a nominal and a high clock rates, the system comprising: a sync detection element for recognizing a sync pattern within the stream of data and generating a sync detected signal, the sync detected signal being clocked at the nominal clock rate; a counter, clocked at the high clock rate, for providing a delay from the last data pulse in the sync detected signal within the stream of data, and generating a counter signal when the value of the counter reaches a predetermined value; and a detection window generation element, responsive to the sync detected signal and the counter signal and be clocked at the high clock, for generating the detection windows. ### Claim 2 (depends on 1) The system of claim 1, further comprising a data value decoder element for detecting the value of a bit of user data within the stream of data, the data value decoder element being clocked at the nominal clock rate, and generating one or more data signals corresponding to the value of the detected user data. ### Claim 3 (depends on 1) The system of claim 1, wherein the counter is a presettable down counter. ### Claim 4 (depends on 1) The system of claim 1, wherein the counter signal is generated by a comparator which compares the value of the counter with a comparator predetermined value. ### Claim 5 (depends on 1) The system of claim 1, wherein the high clock rate is a multiple of the nominal clock rate. ### Claim 6 (depends on 5) The system of claim 5, wherein the high clock rate is two or three times the nominal clock rate. ### Claim 7 A method for accurately initiating the generation of detection windows with respect to the detection of a sync pattern within a stream of data, the method comprising the steps of: detecting the sync pattern with the stream of data by a sync detection element being clocked at a nominal clock rate; loading a preset value into a counter, the counter being clocked at a high clock rate; modifying the value of the counter in response to a high clock signal having the high clock rate; enabling a window generating element in response to the detection of the sync pattern; and generating the detection windows by the enabled window generating element in response to the value of the counter having a predetermined value. ### Claim 8 (depends on 7) The system of claim 7, wherein the counter is a presettable down counter. ### Claim 9 (depends on 7) The system of claim 7, wherein the high clock rate is a multiple of the nominal clock rate. ### Claim 10 (depends on 9) The system of claim 9, wherein the high clock rate is two or three times the nominal clock rate.