Exploitation of Modulation Properties For Blind Adaptive Signal Processing

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Research is being conducted to develop and evaluate algorithms that exploit the properties of randomly modulated sine-wave and pulse-train signals to accomplish detection and time-difference-of-arrival (TDOA) estimation, phase-array direction-of-arrival (DOA) estimation and beam/null-steering signal extraction, and periodically time-variant signal correction. Both single-platform and multiple-platform reception is being considered. The properties being exploited include the spectral self-coherence that results from cyclostationarity, and periodic or constant modulus properties. The algorithms being studied perform blind adaptive signal processing which circumvents the need for training signals, pilot signals, preambles, knowledge of DOA, and so on, which are typically required for conventional adaptive processing. The detection and TDOA algorithms under investigation use FFT-based measurements of auto- and cross-spectral correlation to perform signal- selective detection and TDOA estimation. The phase-array algorithms use singular-value-decomposition and projection of cyclic correlation matrices to accomplish signal-selective DOA estimation and to accomplish beam/null-steering signal extraction by performing spectral self-coherence restoral. The signal correction algorithms use both carrier-modulus and base-band-modulus restoral to adapt periodically time-variant (frequency-shifting) filters for cochannel interference rejection, and correction of multipath and other distortion. Some algorithms employ both self-coherence restoral and modulus restoral. The a priori information required by all the algorithms being investigated is knowledge of at least one frequency of cyclostationarity - typically for the signal of interest - such as a baud rate or carrier frequency and, in some cases, knowledge of such frequencies for both the signal of interest and interfering signals. The research being conducted is based on both theoretical analysis and computer simulations. This research focusses on significant problems and is being conducted by a well qualified researcher. Support is highly recommended.