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    • 1. 发明授权
    • Filtering a read signal to attenuate secondary pulses caused by pole
tips of a thin film magnetic read head
    • 滤除读取信号以衰减由薄膜磁头读取头的极尖引起的次脉冲
    • US5623377A
    • 1997-04-22
    • US222666
    • 1994-04-04
    • Richard T. BehrensNeal GloverTrent O. DudleyAlan J. ArmstrongChristopher P. ZookWilliam G. Bliss
    • Richard T. BehrensNeal GloverTrent O. DudleyAlan J. ArmstrongChristopher P. ZookWilliam G. Bliss
    • G11B5/09G11B20/10H03H17/02H03H17/06H04B3/06G11B5/035
    • H03H17/06G11B20/10009G11B5/09H03H17/02
    • A filter for compensating discrete secondary pulse formations associated with a data stream of discrete main pulses produced from data read from magnetic media. The filter's impulse response comprises a center coefficient with side compensating coefficients for attenuating the secondary pulses when the input signal is convolved with the impulse response. The magnitude and delay of the compensation coefficients are programmable and are adaptively adjusted to optimize the impulse response for a given environment. In a traditional FIR embodiment, two delay lines are used to generate the two programmable delays between the center coefficient and side compensation coefficients. In the preferred embodiment, an IIR filter provides the two programmable delays using only one delay line thereby reducing the size and cost of the circuit. Also in the preferred embodiment, the data stream is interleaved into an even and odd data stream and processed in parallel by two filters in order to double the throughput. Further, the pre-cursor correcting portion of the filter can be disabled in order to avoid delaying the data stream while still canceling the post-cursor secondary pulses. The filter also comprises attenuation and adder means to match the coincident sample values in amplitude and add them to substantially eliminate the effect of the secondary pulses in the discrete data stream.
    • 用于补偿与从磁介质读取的数据产生的离散主脉冲的数据流相关联的离散次级脉冲形成的滤波器。 滤波器的脉冲响应包括具有侧补偿系数的中心系数,用于当输入信号与脉冲响应卷积时衰减次级脉冲。 补偿系数的幅度和延迟可编程,并进行自适应调整,以优化给定环境的脉冲响应。 在传统的FIR实施例中,使用两条延迟线来产生中心系数和侧面补偿系数之间的两个可编程延迟。 在优选实施例中,IIR滤波器仅使用一个延迟线提供两个可编程延迟,从而减小电路的尺寸和成本。 同样在优选实施例中,数据流被交织成偶数和奇数数据流,并且由两个滤波器并行处理,以使吞吐量翻倍。 此外,可以禁用滤波器的前光标校正部分,以避免在仍然取消后光标次级脉冲的同时延迟数据流。 滤波器还包括衰减和加法器装置,以使幅度上重合的采样值相匹配,并将它们相加,以基本上消除离散数据流中次级脉冲的影响。
    • 8. 发明授权
    • Method and apparatus for calibrating an analog filter in a sampled
amplitude read channel
    • 用于校准采样振幅读通道中的模拟滤波器的方法和装置
    • US5903857A
    • 1999-05-11
    • US751832
    • 1996-11-18
    • Richard T. BehrensTyson TuttleKent D. AndersonTrent O. DudleyWilliam G. Bliss
    • Richard T. BehrensTyson TuttleKent D. AndersonTrent O. DudleyWilliam G. Bliss
    • G11B20/10G06F17/10G11B5/035
    • G11B20/10055G11B20/10009G11B20/10037G11B20/10481
    • A method and apparatus for calibrating an analog equalizer in a sampled amplitude read channel is disclosed wherein the filter's frequency response is measured and calibrated directly. This is accomplished by injecting a known periodic signal into the analog filter and measuring a spectrum value at a predetermined frequency. The filter parameters are adjusted accordingly until the spectrum reaches a predetermined target value. In the preferred embodiment, the analog filter comprises at least one second order low pass filter (referred to as a biquad filter), and the filter's spectrum is adjusted relative to the well known parameters f.sub.o and Q. Specifically, the parameters f.sub.o and Q are optimized relative to a power measurement at predetermined harmonics of the input signal. In this manner, the present invention enables auto-calibration of the analog equalizer without reading any data from the disc. Furthermore, the calibration process can be executed during the storage system's normal operation without significantly degrading its overall performance.
    • 公开了一种用于校准采样振幅读通道中的模拟均衡器的方法和装置,其中滤波器的频率响应被直接测量和校准。 这是通过将已知的周期信号注入模拟滤波器并以预定频率测量频谱值来实现的。 相应地调整滤波器参数,直到频谱达到预定的目标值。 在优选实施例中,模拟滤波器包括至少一个二阶低通滤波器(称为双二阶滤波器),并且相对于众所周知的参数fo和Q调节滤波器的频谱。具体地,参数fo和Q是 相对于输入信号的预定谐波处的功率测量而优化。 以这种方式,本发明能够在不从盘读取任何数据的情况下自动校准模拟均衡器。 此外,可以在存储系统的正常操作期间执行校准过程,而不会显着降低其整体性能。
    • 10. 发明授权
    • Fault tolerant sync mark detector enabled relative to a frequency of an
acquisition preamble for sampled amplitude recording
    • 容错同步标记检测器相对于采样幅度记录的采集前导码的频率启用
    • US5729396A
    • 1998-03-17
    • US440268
    • 1995-05-12
    • Trent O. DudleyRichard T. BehrensChristopher P. Zook
    • Trent O. DudleyRichard T. BehrensChristopher P. Zook
    • G11B5/012G11B20/10G11B20/14G11B27/30G11B5/09
    • G11B20/10055G11B20/10009G11B20/10037G11B20/1403G11B27/30G11B27/3027G11B5/012G11B2020/1476
    • A sampled amplitude read channel reads data from a magnetic medium by detecting digital data from a sequence of discrete time sample values generated by sampling an analog read signal from a read head positioned over the magnetic medium. The digital data comprises a preamble field followed by a sync mark followed by a data field. Timing recovery in the read channel synchronizes to a phase and frequency of the preamble field and a sync detector detects the sync mark in order to frame operation of an RLL decoder for decoding the detected data field. To decrease the probability of early misdetection, the sync mark is chosen to have minimum correlation with shifted versions of the sync mark concatenated with the preamble field. To further increase the fault tolerance, the sync mark detector is enabled by timing recovery relative to the end of the preamble field. A state machine in timing recovery generates expected sample values used to acquire the preamble field, and a current state of the state machine indicates when the preamble ends relative to a predetermined clock interval. In this manner, the search for an appropriate sync mark need only look for minimum correlation during shifts at the predetermined clock interval, thereby increasing the fault tolerant characteristic of the sync mark.
    • 采样幅度读取通道从通过从位于磁性介质上的读取头采样模拟读取信号而产生的离散时间采样值的序列中检测数字数据,从磁性介质读取数据。 数字数据包括前同步码字段,随后是同步标记,后跟数据字段。 读通道中的定时恢复与前同步码字段的相位和频率同步,并且同步检测器检测同步标记,以便对RLL解码器进行帧操作,以对检测到的数据字段进行解码。 为了降低早期错误检测的可能性,选择同步标记与与前同步码字段连接的同步标记的移位版本具有最小相关性。 为了进一步增加容错能力,同步标记检测器通过相对于前同步码字段结束的定时恢复来启用。 定时恢复中的状态机产生用于获取前导字段的预期采样值,并且状态机的当前状态指示前导码相对于预定时钟间隔何时结束。 以这种方式,搜索适当的同步标记仅需要在预定时钟间隔期间寻找在移位期间的最小相关性,从而增加同步标记的容错特性。