Frequency Division in Speech Bandwidth Reduction

The following phenomena are discussed in relation to experimental observations on a number of frequency division schemes: “division” of a wave containing several frequencies; phase ambiguity; and strobing. Phase ambiguity is believed to be a fundamental limitation, and the results of a number of previous experiments are attributed to its effects

A new VLSI smart sensor for collision avoidance inspired by insect vision

An analog VLSI implementation of a smart microsensor that mimics the early visual processing stage in insects is described with an emphasis on the overall concept and the front-end detection. The system employs the 'smart sensor' paradigm in that the detectors and processing circuitry are integrated on the one chip. The integrated circuit is composed of sixty channels of photodetectors and parallel processing elements. The photodetection circuitry includes p-well junction diodes on a 2μm CMOS process and a logarithmic compression to increase the dynamic range of the system. The future possibility of gallium arsenide implementation is discussed. The processing elements behind each photodetector contain a' low frequency differentiator where subthreshold design methods have been used. The completed IC is ideal for motion detection, particularly collision avoidance tasks, as it essentially detects distance, speed & bearing of an object. The Horridge Template Model for insect vision has been directly mapped into VLSI and therefore the IC truly exploits the beauty of nature in that the insect eye is so compact with parallel processing, enabling compact motion detection without the computational overhead of intensive imaging, full image extraction and interpretation. This world-first has exciting applications in the areas of automobile anti-collision, IVHS, autonomous robot guidance, aids for the blind, continuous process monitoring/web inspection and automated welding, for example.D. Abbott, A. Moini, A. Yakovieff, X.T. Nguyen, A. Blanksby, G. Kim, A. Bouzerdoum, R.E. Bogner, K. Eshraghia

Autofocus for inverse synthetic aperture radar (ISAR) imaging

Autofocus is a key step of inverse synthetic aperture radar (ISAR) imaging. In this paper four new approaches to autofocussing based on the application of beamforming and subspace concepts to ISAR imaging are developed. Their relations to maximum likelihood (ML) estimation are identified. A common feature of these techniques is the estimation of the complex vector formed by the exponential function of phase rather than phase itself so that phase unwrapping is obviated. The Cramer–Rao lower bound (CRLB) of the estimated complex vector corresponding to translational motion and the CRLB of the estimated distance between two scatterers are derived. The results of processing simulated and real data confirm the validity of proposed approaches.Zhishun She, D. A. Gray and R. E. Bogne