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US 5,491,724 AGranted
Mean phase predictor for maximum a posteriori demodulator
AssigneeChirp Corporation
InventorRichard A. Altes
Life of this patent
Estimating the term…
Abstract
A system and method for optimal maximum a posteriori (MAP) demodulation using a novel mean phase predictor. The mean phase predictor conducts cumulative averaging over multiple blocks of phase samples to provide accurate prior mean phases, to be input into a MAP phase estimator.
Claims16
A maximum a posteriori demodulator, comprising:
- a maximum a posteriori (MAP) estimator receiving a block of N phase samples {.alpha.(.DELTA.), . . . ,.alpha.(N.DELTA.)} and a block of N prior mean phase estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m (N.DELTA.)}, wherein the estimator generates a block of N phase estimates {.theta.(.DELTA.), . . . ,.theta.(N.DELTA.)};
- and
- a mean phase predictor, comprising:
- a cumulative averager receiving the block of phase estimates {.theta.(.DELTA.), . . . ,.theta.(N.DELTA.)} and averaging the block with corresponding elements from previous block averages so as to provide the block of prior mean phase estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m (N.DELTA.)};
- a linear predictor receiving the prior mean phase estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m (N.DELTA.)} and predicting a new prior mean phase estimate .theta..sub.m [(N+1).DELTA.];
- and
- a shift register receiving the prior mean estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m (N.DELTA.)} and new prior mean phase estimate .theta..sub.m [(N+1).DELTA.] such that the first in time prior mean estimate .theta..sub.m (.DELTA.) is shifted out and a new block of prior mean phase estimates .theta..sub.m (2.DELTA.), . . . ,.theta..sub.m [(N+1).DELTA.] is provided to the MAP estimator at time (N+1).DELTA..
4 more elements
A method of maximum a posteriori demodulation, the method comprising the steps of:
- receiving a block of N phase samples {.alpha.(.DELTA.), . . . ,.alpha.(N.DELTA.)} and a block of N prior mean phase estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m (N.DELTA.)};
- estimating a block of N phase estimates {.theta.(.DELTA.), . . . ,.theta.(N.DELTA.)} from the received block of phase samples and the received block of prior mean phase estimates;
- averaging the block of phase estimates {.theta.(.DELTA.), . . . ,.theta.(N.DELTA.)} with corresponding elements from previous block averages so as to provide a cumulative average block of prior mean phase estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m (N.DELTA.)};
- predicting a new prior mean phase estimate .theta..sub.m [(N+1).DELTA.] from the cumulative average block of prior mean phase estimates;
- and
- generating a new block of prior mean phase estimates {.theta..sub.m (.DELTA.), . . . ,.theta..sub.m [(N+1).DELTA.]} at time (N+1).DELTA. from the cumulative average block of prior mean phase estimates and the new prior mean phase estimate.
3 more elements
A maximum a posteriori demodulator, comprising:
- means for estimating a block of phase samples and a block of prior mean phase estimates, said estimating means providing a block of phase estimates;
- means, responsive to said estimating means, for averaging the block of phase estimates with corresponding elements from previous block averages, said averaging means providing a block of prior mean phase estimates;
- means, responsive to said averaging means, predicting a new prior mean phase estimate from the block of prior mean phase estimates;
- and
- a circuit receiving the block of prior mean phase estimates and new prior mean phase estimate, said circuit capable of discarding the first in time prior mean phase estimate and adjoining the new prior mean phase estimate to the block of prior mean phase estimates.
2 more elements
A maximum a posteriori (MAP) demodulator, comprising:
- a mean phase predictor generating a block of prior mean phases;
- a MAP estimator receiving phase autocovariance function samples R.sub..theta. (i.DELTA.), a block of phase samples {.alpha.[(k+j+1).DELTA.], . . . ,.alpha.[(k+j+N).DELTA.]}, and the block of prior mean phases {.theta..sub.m [(k+j+1).DELTA.], . . . ,.theta..sub.m [(k+j+N).DELTA.]}, wherein the estimator generates a block of phase estimates {.theta.[(k+j+1).DELTA.], . . . .theta.[(k+j+N).DELTA.]};
- and
- a shift circuit receiving the block of phase estimates {.theta.[(k+j+1).DELTA.], . . . .theta.[(k+j+N).DELTA.]} and generating updated mean phase estimates that are provided to the mean phase predictor.
1 more element
Dependencies are inferred from the claim text.