Zhaonian Zhang

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A portable acoustic micro-Doppler radar system for the acquisition of human gait signatures in indoor and outdoor environments is reported. Signals from an accelerometer attached to the leg support the identification of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described in this paper is simpler and offers(More)
A micro-Doppler active acoustic sensing system is described. We report its use in acquiring gait signatures of humans and four-legged animals in indoor and outdoor environments. Signals from an accelerometer attached to the leg support the interpretation of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described(More)
Active acoustic scene analysis is a promising approach to distributed persistent surveillance in sensor networks. We report on the design of bandpass sampling technique for an acoustic micro-Doppler sonar to reduce the data rate to as low as 85 kbps. We then explore the use of Gaussian mixture models for human identification. We compare the classification(More)
In this paper, we report on the use of a microphone array and enclosure in the Hopkins Acoustic Surveillance Unit (HASU) for bearing estimation and tracking of a moving vehicle at a close range. We use correlation based algorithms and we report bearing estimation results from moving vehicles at various constant velocities. The estimation results are in good(More)
State-space modeling of fully differential <i>Gm-C</i> filters with weak nonlinearities is used to develop a fast algorithm for intermodulation distortion estimation. It results in simple analytic formulas that apply directly to <i>Gm-C</i> filters of <i>any order</i> and any fully balanced topology. The algorithm has been verified using SpectreS (SPICE)(More)