Method and apparatus for correlation-sensitive adaptive sequence detection
AssigneeCarnegie Mellon University
InventorsAleksandar Kavcic, Jose M. F. Moura
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Abstract
The present invention is directed to a method of determining branch metric values for branches of a trellis for a Viterbi-like detector. The method includes the step of selecting a branch metric function for each of the branches at a certain time index. The method also includes the step of applying the selected function to a plurality of time variant signal samples to determine the metric values.
Claims28
A method of determining branch metric values for branches of a trellis for a Virterbi-like detector, comprising:
- selecting a branch metric function for each of the branches at a certain time index;
- and
- applying each of said selected functions to a plurality of signal samples to determine the metric value corresponding to the branch for which the applied branch metric function was selected, wherein each sample corresponds to a different sampling time instant.
A method of determining branch metric values for branches of a trellis for a Viterbi-like detector, comprising:
- selecting a branch metric function for each of the branches at a certain time index from a set of signal-dependent branch metric functions;
- and
- applying each of said selected functions to a plurality of signal samples to determine the metric value corresponding to the branch for which the applied branch metric function was selected, wherein each sample corresponds to a different sampling time instant.
A method of generating a signal-dependent branch weight for branches of a trellis for a Viterbi-like detector, comprising:
- selecting a plurality of signal samples, wherein each sample corresponds to a different sampling time instant;
- calculating a first value representing a branch-dependent joint probability density function of a subset of said signal samples;
- calculating a second value representing a branch dependent joint probability density function of said signal samples;
- calculating the branch weight from said first and second values;
- and
- outputting the branch weight.
A method of generating a branch weight for branches of a trellis for a Viterbi-like detector, wherein the detector is used in a system having Gaussian noise, comprising:
- selecting a plurality of signal samples, wherein each sample corresponds to a different sampling time instant;
- calculating a first value representing a logarithm of a quotient of a determinant of a trellis branch dependent covariance matrix of said signal samples and a determinant of a trellis branch dependent covariance matrix of a subset of said signal samples;
- calculating a second value representing a quadratic of said signal samples less a plurality of target values normalized by a trellis branch dependent covariance of said signal samples;
- calculating a third value representing a quadratic of a subset of said signal samples less a plurality of channel target values normalized by a trellis branch dependent covariance of said subset of signal samples;
- calculating the branch weight from said first, second, and third values;
- and
- outputting said branch weight.
A method for detecting a sequence that exploits the correlation between adjacent signal samples for adaptively detecting a sequence of symbols stored on a high density magnetic recording device, comprising the steps of:
- (a) performing a Virterbi-like sequence detection on a plurality of signal samples using a plurality of correlation sensitive branch metrics;
- (b) outputting a delayed decision on the recorded symbol;
- (c) outputting a delayed signal sample;
- (d) adaptively updating a plurality of noise covariance matrices in response to said delayed signal samples and said delayed decisions;
- (e) recalculating said plurality of correlation-sensitive branch metrics from said noise covariance matrices using subsequent signal samples;
- and
- (f) repeating steps (a)-(e) for every new signal sample.
A method for detecting a sequence that exploits the correlation between adjacent signal samples for adaptively detecting a sequence of symbols through a communications channel having intersymbol interference, comprising the steps of:
- (a) performing a Virterbi-like sequence detection on a plurality of signal samples using a plurality of correlation sensitive branch metrics;
- (b) outputting a delayed decision on the transmitted symbol;
- (c) outputting a delayed signal sample;
- (d) adaptively updating a plurality of noise covariance matrices in response to said delayed signal samples and said delayed decisions;
- (e) recalculating said plurality of correlation-sensitive branch metrics from said noise covariance matrices using subsequent signal samples;
- and
- (f) repeating steps (a)-(e) for every new signal sample.
A detector circuit for detecting a plurality of data from a plurality of signal samples read from a recording medium, comprising:
- a Viterbi-like detector circuit, said Viterbi-like detector circuit for producing a plurality of delayed decisions and a plurality of delayed signal samples from a plurality of signal samples;
- a noise statistics tracker circuit responsive to said Viterbi-like detector circuit for updating a plurality of noise covariance matrices in response to said delayed decisions and said delayed signal samples;
- and
- a correlation-sensitive metric computation update circuit responsive to said noise statistics tracker circuit for recalculating a plurality of correlation-sensitive branch metrics from said noise covariance matrices, said branch metrics output to said Viterbi-like detector circuit.
A branch metric computation circuit for generating a branch weight for branches of a trellis for a Viterbi-like detector, wherein the detector is used in a system having Gaussian noise, comprising:
- a logarithmic circuit having for each branch an input responsive to a branch address and an output;
- a plurality of arithmetic circuits each having a first input responsive to a plurality of signal samples, a second input responsive to a plurality of target response values, and an output, wherein each of the arithmetic circuits corresponds to each of the branches;
- a sum circuit having for each branch a first input responsive to said output of said logarithmic circuit, a second input responsive to said output of said arithmetic circuit, and an output.
A system for recording information on a magnetic medium, comprising:
- a write signal processing circuit for processing a plurality of data from a data source;
- a write control circuit;
- a write head responsive to said write control circuit for receiving a plurality of signals from said write signal processing circuit, said write head for writing said signals to the recording medium;
- a read control circuit;
- a read head for reading said signals from the recording medium, said read head responsive to said read control circuit;
- and
- a detector circuit for detecting a plurality of data from said read signals, said detector comprising:
- a Viterbi-like detector circuit, said Viterbi-like detector circuit for producing a plurality of delayed decisions and a plurality of delayed signal samples from a plurality of signal samples;
- a noise statistics tracker circuit responsive to said Viterbi-like detector circuit for updating a plurality of noise covariance matrices in response to said delayed decisions and said delayed signal samples;
- and
- a correlation-sensitive metric computation update circuit responsive to said noise statistics tracker circuit for recalculating a plurality of correlation-sensitive branch metrics from said noise covariance matrices, said branch metrics output to said Viterbi-like detector circuit.
A system for recording information on a magnetic medium, comprising;
- a write signal processing circuit for processing a plurality of data from a data source;
- a write control circuit;
- a write head responsive to said write control circuit for receiving a plurality of signals from said write signal processing circuit, said write head for writing said signals to the recording medium;
- a read control circuit;
- a read head for reading said signals from the recording medium, said read head responsive to said read control circuit;
- and
- a detector circuit for detecting a plurality of data from said read signals, said detector circuit having a circuit for selecting a branch metric function for each branch of a trellis and for applying said metric function to a plurality of time variant signal samples to determine a plurality of branch metric values.
A system for recording information on a magnetic medium, comprising;
- a write signal processing circuit for processing a plurality of data from a data source;
- a write control circuit;
- a write head responsive to said write control circuit for receiving a plurality of signals from said write signal processing circuit, said write head for writing said signals to the recording medium;
- a read control circuit;
- a read head for reading said signals from the recording medium, said read head responsive to said read control circuit;
- and
- a detector circuit for detecting a plurality of data from said read signals, said detector circuit having a circuit for selecting a branch metric function for each branch of a trellis at a certain time index from a set of signal-dependent branch metric functions and for applying said selected function to a plurality of time variant signal samples to determine a plurality of branch metric values.
A system for recording information on a magnetic medium, comprising;
- a write signal processing circuit for processing a plurality of data from a data source;
- a write control circuit;
- a write head responsive to said write control circuit for receiving a plurality of signals from said write signal processing circuit, said write head for writing said signals to the recording medium;
- a read control circuit;
- a read head for reading said signals from the recording medium, said read head responsive to said read control circuit;
- and
- a detector circuit for detecting a plurality of data from said read signals, said detector circuit having a tapped-delay line branch metric computation circuit, the computation circuit including:
- a logarithmic circuit having for each branch an input responsive to a branch address and an output;
- a plurality of arithmetic circuits each having a first input responsive to a plurality of signal samples, a second input responsive to a plurality of target response values, and an output, wherein each of the arithmetic circuits corresponds to each of the branches;
- a sum circuit having for each branch a first input responsive to said output of said logarithmic circuit, a second input responsive to said output of said arithmetic circuit, and an output.
A computer-readable medium having stored thereon instructions which, when executed by a processor, cause said processor to perform the steps of:
- selecting a branch metric function for each branch of a trellis for a Viterbi-like detector at a certain time index;
- and
- applying each of said selected functions to a plurality of time variant signal samples to determine a branch metric value corresponding to the branch for which the applied branch metric function was selected.
A computer-readable medium having stored thereon instructions which, when executed by a processor, cause said processor to perform the steps of:
- selecting a branch metric function for each branch of a trellis for a Viterbi-like detector at a certain time index from a set of signal-dependent branch metric functions;
- and
- applying each of said selected functions to a plurality of time variant signal samples to determine a branch metric value corresponding to the branch for which the applied branch metric function was selected.
Dependencies are inferred from the claim text.