Rockwell Collins, Inc.

Steven L White

Thomas L Tapp

Rodney L Mickelson

Joseph C Whited

Billy D Hart

Christopher J Swanke

An apparatus and method provides efficient parallel processing for use with a single-bit sampler that provides single-bit samples at a high sample rate. A serial-to-parallel converter converts the single-bit samples into parallel single-bit samples at a reduced sample rate. A digital quadrature mix performs a frequency shift to the parallel single-bit samples and simultaneously performs a real-to-complex conversion of the parallel single-bit samples from the serial-to-parallel converter to provide parallel I and Q output values at an intermediate frequency. The serial-to-parallel converter has shift register stages that provide a memory for use in functional realization of a boxcar filter and decimation-by-two in the digital quadrature mix. The digital quadrature mix utilizes logic to route and invert the parallel single-bit samples resulting in the parallel I and Q single-bit output values. Additional filter and decimate stages may be used to process the parallel I and Q single-bit output values.

Efficient method and apparatus for parallel processing for use with high-speed single-bit sampling

An equalizer is used with complex modulation modems to reduce intersymbol interference. The equalizer includes an equalizer filter that receives an input data signal and adapts to compensate for the noisy communications channels to reduce intersymbol interference to the input signal. A branch metric computer demodulates the equalizer filter adapted input data signal. A decision device delivers an alpha value, starting phase information and confidence values from the demodulated input data signal. A gain determination function receives the confidence values and determines adaptation gain for the equalizer filter. A remodulator receives the alpha value and starting phase information and remodulates the alpha value and starting phase information into a remodulated data signal. A summing function compares the remodulated data signal to a delayed version of the input signal to generate an error signal for the equalizer filter to adjust the equalizer filter.

Equalizer for complex modulations in very noisy environments

A bandwidth efficient advanced modulation waveform modem using concatenated iterative turbo coding and continuous phase modulation is disclosed. A demodulator in the modem has a turbo decoder and a decision feedback carrier and time tracking algorithm to track a carrier and adjust timing. The decision feedback carrier and time tracking algorithm may use an APP decoder as a decision device to provide symbol decisions at a high error rate and low latency for a coded input data stream. A symbol phase estimator produces a symbol phase error estimate from the symbol decisions. An erasure decision function decides which symbol decisions are correct and which symbol decisions are erasures. A carrier tracking function receives the symbol phase error estimates when the symbol decisions are correct and receives erasure inputs when the symbol decisions are erasures to maintain carrier tracking.

Synchronization method and apparatus for modems based on jointly iterative turbo demodulation and decoding

Acquisition of a waveform such as a continuous-phase modulation (CPM) waveform is described. In one embodiment of the invention, the invention is directed to a method and apparatus for acquiring a waveform as defined by MIL-STD-188-181B including the preamble of such a waveform at a performance level defined by the standard. The present invention provides solutions to at least four primary issues presented in acquiring a CPM waveform such as the MIL-STD-188-181B compliant waveform. These primary problems include searching for the preamble, determination of the symbol rate, determination of an initial carrier frequency error (Doppler), determination of an initial carrier phase, and determination of the start-of-message to establish an absolute time marker within the waveform.

Acquisition of a continuous-phase modulation waveform

A method of excising one or more narrow-band interfering signals in a direct sequence spread spectrum receiver that performs a magnitude spectral analysis on baseband signals in a detection channel to determine which frequency bins in the spectral analysis output contain the interfering narrow-band signals by comparing the magnitude of the signals in the frequency bins to a threshold. The corrupted frequency bins are determined by the signal magnitudes exceeding the threshold and band reject filters excise the narrow-band signals in the signal channel in accordance with the corrupted frequency bins.

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Cedar Rapids, IA, United States of America

Steven L White