Abstract: A feature imaging and adaptive focusing synthetic aperture processing met provides improved sharpness and easier classification of images derived from radar and sonar echo data by applying adaptive focusing and feature imaging to a sequence of echo data.

Abstract: A system and method for decoding by identification of the most likely phase coded signal corresponding to received data. The present invention has particular application to communication with signals that experience spurious random phase perturbations. The generalized estimator-correlator uses a maximum a posteriori (MAP) estimator to generate phase estimates for correlation with incoming data samples and for correlation with mean phases indicative of unique hypothesized signals. The result is a MAP likelihood statistic for each hypothesized transmission, wherein the highest value statistic identifies the transmitted signal.

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.

Abstract: A system and method for optimal maximum a posteriori (MAP) demodulation. The present invention incorporates neural network technology, i.e., a Hopfield network, (1) to replace the function of the traditional, suboptimal phase-locked loop in an FM receiver and/or (2) to optimally estimate a discrete phase value using an expected value (obtained from the mean of the prior probability distribution of the phase) and statistical dependence between different phase values in a block of samples (described by the covariance matrix of the prior phase distribution). The definition of the Hopfield network includes particular bias currents, feedback weights and a sigmoid function for solving the nonlinear integral equation associated with optimal demodulation. The present invention also includes a signal classifier having a plurality of angled modulators for modeling different phase modulation processes.

Abstract: A specially generated broad band radiation signal is passed through a radiation path. The output radiation as modified by that path is compared with the transmitted radiation in a manner to characterize in the frequency domain the radiation path transfer function or the modified radiation by a few constants of a Taylor series expansion. One application of this technique is in sonar or radar work for characterizing the shape of an object in a manner independent of its velocity but with a high signal-to-noise ratio and very good resolution. The comparison of the modified radiation with the transmitted radiation in order to determine the Taylor series coefficients is accomplished by a correlation or matched filtering operation. The technique in its broadest sense also has applications for compensating communication circuits and in parameterizing human speech.

Abstract: A technique for monitoring an object space having known cluttering objects for determining when an object of interest enters the object space. An application of the technique is in sonar supervision of a river or other body of water wherein the entrance into the monitored space by the object of interest, such as a shark or swimmer, is readily detected. Such detection is accomplished by illuminating a monitored object space with broad band radiation. Radiation either reflected from or transmitted through the object is then converted to an electrical signal that is passed through a bank of bandpass filters. The filter outputs are weighted to maximize the receiver's response to the object of interest while minimizing the response to clutter and noise. The technique is based upon the observation that different reflectors give rise to different echo spectra when the reflectors are illuminated with a broad band signal.