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US 6,587,521 B1Granted
Signal estimator and program stored memory medium
AssigneeNEC Corporation
InventorHitosi Matui
Life of this patent
Estimating the term…
Abstract
A signal estimator is provided that can track a large frequency offset. A received signal distorted in a transmission path is phase-rotated by the phase rotator (102) and is then estimated by the maximum likelihood sequence estimator (MLSE) (103). The phase detector (105) detects a phase difference between a signal obtained by delaying the phase-rotated signal and information about a minimum path metric in the Viterbi algorithm operation by the MLSE. After the phase difference signal is filtered, the voltage-controlled oscillator (VCO) receives the filtered signal. Then, the phase rotation is controlled with the output of the VCO.
Claims15
A signal estimator, comprising:
- phase rotation means for rotating the phase of a received signal;
- estimation means for estimating said received signal with an output signal of said phase rotation means, based on a Viterbi algorithm, to obtain an estimation result, and then outputting said estimation result and a minimum error signal used to create a minimum path metric value in an estimation operation;
- delay means for delaying the output signal of said phase rotation means according to a period during which said estimation means outputs said minimum error signal;
- phase detection means for detecting a phase shift of said received signal based on said minimum error signal and said delay means;
- filter means for limiting the frequency band of an output signal from said phase detection means;
- and
- signal generation means for generating a signal of a frequency proportional to the output of said filter means and then controlling said phase rotation means to rotate the phase of said received signal.
4 more elements
A signal estimator comprising:
- phase rotation means for rotating the phase of a received signal based on a control signal;
- a plurality of subtraction means each for obtaining as an error signal a difference between said received signal and plural sample signals;
- estimation means having means for outputting as a minimum error signal said error signal corresponding to a minimum path, and means for estimating said received signal with an output signal from said phase rotation means, based on a Viterbi algorithm, to obtain an estimation result, and then outputting said estimation result and said minimum error signal;
- delay means for delaying said output signal from said phase rotation means according to a period during which said estimation means outputs said minimum error signal;
- phase detection means for detecting a phase shift of said received signal based on said minimum error signal and an output signal from said delay means;
- filter means for performing a filtering process to limit the frequency band of an output signal from said phase detection means;
- and
- signal generation means for generating a signal of a frequency proportional to an output signal from said filter means and then outputting the generated signal as said control signal.
5 more elements
A method for correcting a phase shift of a received signal, comprising the steps of:
- rotating the phase of a received signal based on a control signal;
- estimating said received signal with said phase-rotated signal, based on a Viterbi algorithm, to obtain an estimation result, and then outputting said estimation result and a minimum error signal used to create a minimum path metric value in an estimation operation;
- delaying said phase-rotated signal according to a period during which said minimum error signal is output;
- detecting a phase shift of said received signal based on said minimum error signal and said delayed output signal;
- limiting the frequency band of said detected signal of which the phase is shifted;
- and
- generating a signal of a frequency proportional to a detected signal of which the frequency band is limited, and then outputting the generated signal as said control signal.
4 more elements
A memory medium wherein a program is stored, said program comprising the steps of:
- rotating the phase of a received signal;
- estimating said received signal with said phase rotated signal, based on a Viterbi algorithm, to obtain an estimation result, and then outputting said estimation result and a minimum error signal used to create a minimum path metric value in said estimation operation;
- delaying said phase rotated signal according to a period during which said estimation means outputs said minimum error signal;
- detecting a phase shift of said received signal based on said minimum error signal and said delay signal;
- performing a filtering process to limit the frequency band of said phase detected signal;
- and
- generating a signal of a frequency proportional to said filtered signal, whereby said signal rotates the phase of said received signal in said phase rotation step, based on said generated signal.
4 more elements
Dependencies are inferred from the claim text.