Zero phase restart interpolated timing recovery in a sampled amplitude read channel
DCFirst Claim
1. A sampled amplitude read channel for detecting data stored on a storage medium by sampling pulses in an analog read signal emanating from a read head positioned over the medium, comprising:
- (a) a sampling device for asynchronously sampling the analog read signal to generate a sequence of discrete time, asynchronous sample values;
(b) interpolated timing recovery for generating a sequence of substantially synchronous sample values from the asynchronous sample values using an interpolation interval computed relative to a difference between the asynchronous sample values and synchronous sample values;
(c) a zero phase restart circuit, responsive to the asynchronous sample values, for computing an initial interpolation interval at a beginning of an acquisition mode; and
(d) a discrete time sequence detector for detecting the data from the substantially synchronous sample values,wherein the zero phase restart circuit comprises a processor for computing a sampling phase offset using a predetermined number of the asynchronous sample values, and the processor computes a real and imaginary component of the asynchronous sample values in the frequency domain.
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Abstract
A sampled amplitude read channel is disclosed for disc storage systems which asynchronously samples an analog read signal, equalizes the resulting discrete time sample values according to a target partial response, extracts synchronous sample values through interpolated timing recovery, and detects digital data from the synchronous sample values using a Viterbi sequence detector. The interpolated timing recovery comprises a zero phase restart circuit for minimizing an intial phase error between expected sample values and interpolated sample values at the beginning of an acquisition mode by computing an initial sampling phase offset.
118 Citations
15 Claims
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1. A sampled amplitude read channel for detecting data stored on a storage medium by sampling pulses in an analog read signal emanating from a read head positioned over the medium, comprising:
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(a) a sampling device for asynchronously sampling the analog read signal to generate a sequence of discrete time, asynchronous sample values; (b) interpolated timing recovery for generating a sequence of substantially synchronous sample values from the asynchronous sample values using an interpolation interval computed relative to a difference between the asynchronous sample values and synchronous sample values; (c) a zero phase restart circuit, responsive to the asynchronous sample values, for computing an initial interpolation interval at a beginning of an acquisition mode; and (d) a discrete time sequence detector for detecting the data from the substantially synchronous sample values, wherein the zero phase restart circuit comprises a processor for computing a sampling phase offset using a predetermined number of the asynchronous sample values, and the processor computes a real and imaginary component of the asynchronous sample values in the frequency domain. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sampled amplitude read channel for detecting data stored on a storage medium by sampling pulses in an analog read signal emanating from a read head positioned over the medium, comprising:
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(a) a sampling device for sampling the analog read signal to generate a sequence of discrete time sample values; (b) timing recovery for extracting timing information from the discrete time sample values; (c) a zero phase restart circuit for computing an initial phase offset between a reference sample and an expected sample at a beginning of an acquisition mode, the initial phase offset computed using more than four of the discrete time sample values; and (d) a discrete time sequence detector for detecting the data from the discrete time sample values. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A sampled amplitude read channel for detecting data stored on a storage medium by sampling pulses in an analog read signal emanating from a read head positioned over the medium, comprising:
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(a) a sampling device for sampling the analog read signal to generate a sequence of discrete time sample values; (b) timing recovery for extracting timing information from the discrete time sample values; (c) a zero phase restart circuit for computing an initial phase offset between a reference sample and an expected sample by computing a discrete fourier transform using a predetermined number of the discrete time sample values; and (d) a discrete time sequence detector for detecting the data from the discrete time sample values. - View Dependent Claims (15)
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Specification