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)
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)
—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)
—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)
We have explored the effects of percolation on the properties of supercapacitors with thin nanotube networks as electrodes. We find the equivalent series resistance, R(ESR), and volumetric capacitance, C(V), to be thickness independent for relatively thick electrodes. However, once the electrode thickness falls below a threshold thickness (∼100 nm for(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)
—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 that(More)
This paper extends previous work to process and combine data from multiple bistatic pairs in a passive multistatic radar system. The previously presented Multistatic Velocity Backprojection (MVBP) combines and visualizes multistatic radar data. MVBP generates a six-dimensional data cube in position and velocity but does not provide a mechanism for detecting(More)