Quadrature vestigial sideband digital communications method and system with correlated noise removal
AssigneeThe Aerospace Corporation
InventorsJohn J. Poklemba, Gregory S. Mitchell, Ronald F. Smith
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Abstract
A quadrature vestigial-sideband (QVSB) method and system with correlated noise removal are embodied in a QVSB receiver with a correlated-noise estimator-subtractor configured to obtain I/Q channel correlated noise estimates for receive-filtered I/Q signals in the QVSB receiver, and to subtract the I/Q channel correlated noise estimates from the receive-filtered I/Q signals to whiten noises entering a quadrature-crosstalk, maximum-likelihood-sequence-estimator (QC-MLSE) of the QVSB receiver.
Claims16
A communications method with correlated noise removal, the method comprising the steps of:
- translating a quadrature vestigial-sideband (QVSB) signal to inphase and quadrature (I/Q) baseband components, rTiq and rTqi;
- filtering the baseband components to generate I and Q channel overlapped filter responses;
- estimating transmitted data content of the I and Q channel overlapped filter responses;
- employing the estimated data content to reconstruct originally transmitted I/Q signals, {tilde over (s)}Tiq and {tilde over (s)}Tqi;
- processing the reconstructed signal components and the inphase and quadrature (I/Q) baseband components to generate correlated-noise estimates, {circumflex over (n)}i and {circumflex over (n)}q;
- subtracting the correlated-noise estimates, {circumflex over (n)}i and {circumflex over (n)}q, from the cross-coupled filtering outputs to yield receive-filtered I/Q signals in white noise, riq and rqi;
- and
- processing the whitened I/Q inputs to provide optimal data estimates, {circumflex over (m)}.
A method for whitening correlated noise, the method comprising the steps of:
- obtaining I/Q channel correlated noise estimates for receive-filtered I/Q signals in a quadrature vestigial-sideband (QVSB) receiver;
- and
- subtracting the I/Q channel correlated noise estimates from the receive-filtered I/Q signals to whiten noises entering a quadrature-crosstalk, maximum-likelihood-sequence-estimator (QC-MLSE) of the QVSB receiver.
A demodulator system with correlated noise removal, comprising:
- a quadrature vestigial-sideband (QVSB) receiver with a correlated-noise estimator-subtractor configured to whiten noises entering a quadrature-crosstalk, maximum-likelihood-sequence-estimator (QC-MLSE) of the QVSB receiver.
A demodulator system with correlated noise removal, comprising:
- a quadrature vestigial-sideband (QVSB) receiver with an iterated receiver structure configured to
- initially generate sub-optimum message sequence estimates in processing receive-filtered signals to generate estimates of correlated noise components of the receive-filtered signals, and
- reduce interference on the receive-filtered signals to white noise for a final stage of maximum-likelihood-sequence-estimation.
A quadrature vestigial-sideband (QVSB) demodulator system with correlated noise removal, comprising:
- a demodulator front-end for translating an incoming signal to inphase and quadrature (I/Q) baseband components, rTiq and rTqi;
- a set of cross-coupled, matched data filters for filtering the baseband components to generate I and Q channel overlapped filter responses;
- an initial quadrature-crosstalk, maximum-likelihood-sequence-estimator (QC-MLSE) for estimating transmitted data content of the I and Q channel overlapped filter responses;
- a transmit waveform reconstructor for employing the estimated data content to reconstruct originally transmitted I/Q signals, {tilde over (s)}Tiq and {tilde over (s)}Tqi;
- a correlated-noise estimator-subtractor for processing the reconstructed signal components and the inphase and quadrature (I/Q) baseband components to generate correlated-noise estimates, {circumflex over (n)}i and {circumflex over (n)}q, and for subtracting the correlated-noise estimates, {circumflex over (n)}i and {circumflex over (n)}q, from the cross-coupled filtering outputs to yield receive-filtered I/Q signals in white noise, riq and rqi;
- and
- a final QC-MLSE for processing the whitened I/Q inputs to provide optimal data estimates, {circumflex over (m)}.
Dependencies are inferred from the claim text.