摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating the analog functions as well as the primary digital functions of the read channel in a single integrated circuit, and preferred embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.
摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating the analog functions as well as the primary digital functions of the read channel in a single integrated circuit, and preferred embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.
摘要:
A synchronous read channel is disclosed which samples an analog read signal from a magnetic read head positioned over a magnetic disk medium, filters the sample values according to a desired partial response, extracts timing information from the filtered sample values, and detects an estimated data sequence from the filtered sample values using a discrete time sequence detector. A Channel Quality circuit accumulates various signals generated by the read channel, such as sample errors, gain errors, timing errors, etc., for use in calibrating the read channel components and estimating the bit error rate.
摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating the analog functions as well as the primary digital functions of the read channel in a single integrated circuit, and preferred embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.
摘要:
A synchronous read channel is disclosed which samples an analog read signal from a magnetic read head positioned over a magnetic disk medium, filters the sample values according to a desired partial response, extracts timing information from the filtered sample values, and detects an estimated data sequence from the filtered sample values using a trellis type sequence detector matched to the partial response. The trellis sequence detector comprises programmable detector levels which allows for maximum flexibility in matching the sequence detector to the partial response.
摘要:
A synchronous read channel is disclosed which samples an analog read signal from a magnetic read head positioned over a magnetic disk medium, filters the sample values according to a desired partial response, extracts timing information from the filtered sample values, and detects an estimated data sequence from the filtered sample values using a discrete time sequence detector. Discrete time timing recovery within the read channel comprises a variable frequency oscillator (VFO) for generating a sampling clock. A center operating frequency of the VFO is adjusted through a programmable register which stores a digital center frequency setting. A phase error is computed from the sample values and combined with the center frequency setting to control the frequency and phase of the sampling clock at the output of the VFO.
摘要:
A Viterbi detector is modified to reduce its implementation complexity. A partial-response signal may be viewed as a sequence of expected samples generated from a finite-state-machine model. In a typical Viterbi demodulator implemented using the add, compare, select (ACS) method, each state in the expected sample sequence model is associated with a hardware module to perform the functions of adding new branch error metrics to path error metrics, comparing path error metrics, and selecting the path having the lowest path error metric. In this invention, an ACS module may have two or more sequence-model states dynamically associated with it, such that at some times one sequence-model state is associated with it and at other times another sequence-model state is associated with it. This reduces the number of ACS modules required and also reduces the size/complexity of the demodulator's path memories which must store one path for each ACS module. Groups of sequence-model states may be chosen to share an ACS module without significant loss in performance as compared to the original, unreduced Viterbi demodulator. The invention supports a wide range of sample models by making the expected sample sequence of an isolated medium transition programmable. The invention reduces the speed at which the detector circuitry must operate relative to the sample rate by allowing multiple samples to be processed simultaneously. Several reduced detectors for specific sample sequence models are presented for particular applications. The invention is applicable to other types of Viterbi detectors, such as decoders for convolutional codes.
摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating the analog functions as well as the primary digital functions of the read channel in a single integrated circuit, and preferred embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.
摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(l,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, error-tolerant sync mark detection, and the ability to recover data when the sync mark is obliterated allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating analog as well as digital functions of the read channel in a single integrated circuit, and embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.
摘要:
A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(1,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, together with the error-tolerant sync mark detection and the ability to recover data when the sync mark is obliterated, allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery. Various embodiments, including an embodiment incorporating the analog functions as well as the primary digital functions of the read channel in a single integrated circuit, and preferred embodiments utilizing a reduced complexity, programmable modified Viterbi detector supporting a broad class of partial response channels are disclosed.