Thomas Higgins

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– We consider a class of MIMO radar emissions in which a coherent spatial beam is formed while the direction is modulated during the pulse width. This type of spatial modulation has a direct analog to the rapid, small movements of the human eye during fixation (staring) to enhance contrast and sensitivity to fine detail. To replicate this passive sensing(More)
—A new spectral-shaping approach is used to design jointly the amplitude window and phase of a tapered NLFM waveform. This approach can produce physical radar emissions with ultra-low sidelobes that support sufficient spectral roll-off to maintain forthcoming spectral compliance requirements. A small SNR loss is traded for a substantial reduction in range(More)
base funding program. All views and opinions expressed here are the authors' own and do not reflect the official position of the U.S. Leveraging the recent development of a physical implementation of arbitrary polyphase codes as spectrally well-contained waveforms, the notion of spatial modulation is developed whereby a time-varying beampattern is(More)
—The sensitivity impact of range straddling in the form of mismatch loss is well known. What is less appreciated, however, is the effect upon dynamic range, particularly for receive filtering that seeks to minimize range sidelobes. For FM-based waveforms, which are readily implementable in a high-power radar system, it is shown that least-squares (LS)(More)
—Inspired by the fixational movements of the human eye, fast-time spatial modulation was recently demonstrated as a particular physically-realizable form of a multiple-input multiple-output (MIMO) radar emission. The attendant coupling of the delay and angle dimensions has been shown to provide a modest improvement in spatial separation, even when using(More)
In three experiments, rats received pairings of flavor conditioned stimuli with polycose unconditioned stimuli, in either a simultaneous or a sequential relation. Both temporal relations produced excellent conditioned increases in consumption of the flavors. Separate presentation of the flavors resulted in extinction in both cases. However, restoring the(More)
—Gradient descent is an iterative method of determining the minima or maxima of a function. The algorithm can be used to solve a linear system of equations when the computational cost of a matrix inverse is too expensive for an application. Here, gradient descent is applied to Adaptive Pulse Compression (APC), yielding the GraD-APC algorithm. Specifically,(More)
—The reiterative super-resolution (RISR) algorithm was previously developed to enable adaptive beamforming with as few as one time snapshot, is robust to temporally correlated signals, and accounts for array calibration errors. Here a gain-constrained version (denoted GC-RISR) is derived followed by a partially-constrained version (PC-RISR). It is shown(More)
BACKGROUND Surgery under cardiopulmonary bypass (CPB) is still associated with significant cardiovascular morbidity in both pediatric and adult patients but the mechanisms are not fully understood. Abnormalities in coronary flow and function have been suggested to play an important role. Prior studies suggest protective effects on coronary and myocardial(More)
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