Solid-State Microwave Electronics

Contains reports on three research projects.National Aeronautics and Space Administration (Grant NGR-22-009-163

Speech Communication

Contains reports on three research projects.U. S. Air Force Cambridge Research Laboratories under Contract F19628-69-C-0044National Institutes of Health (Grant 5 RO1 NS04332-09)M.I.T. Lincoln Laboratory Purchase Order CC-57

Performance improvement for wideband beamforming with white noise reduction based on sparse arrays

A method is proposed for reducing the effect of white noise in wideband sparse arrays via a combination of a judiciously designed transformation followed by highpass filters. The reduced noise level leads to a higher signal to noise ratio for the system, which can have a significant effect on the performance of various beamforming methods. As a representative example, the reference signal based (RSB) and the Linearly Constrained Minimum Variance (LCMV) beamformers are employed here to demonstrate the improved beamforming performance, as confirmed by simulation results

FPGA implementation of a TVWS up- and down converter using non-power-of-two FFT modulated filter banks

This paper addresses an oversampled filter bank (OSFB) approach to up- and down-convert any or all of the 40 channels in the United Kingdom's TV white space (TVWS). We particularly consider the use of non-power-of-two fast Fourier transforms (FFTs), which provides a greater choice of design parameters over existing OSFB implementations. Using a field-programmable gate array (FPGA) software defined radio (SDR) platform, we compare two different 40-point FFT-based implementations of the system - one fully parallelised, one serialised- with an existing design using a radix-two 64-point FFT in terms of implementation cost and power consumption

Finite Rate of Innovation Based Modeling and Compression of ECG Signals

Mobile health is gaining increasing importance for society and the quest for new power efficient devices sampling biosignals is becoming critical. We discuss a new scheme called Variable PulseWidth Finite Rate of Innovation (VPW-FRI) to model and compress ECG signals. This technique generalizes classical FRI estimation to enable the use of a sum of asymmetric Cauchy-based pulses for modeling electrocardiogram (ECG) signals. We experimentally show that VPW-FRI indeed models ECG signals with increased accuracy compared to current standards. In addition, we study the compression efficiency of the method: compared with various widely used compression schemes, we showcase improvements in terms of compression efficiency as well as sampling rate

Design and Instrumentation of a Measurement and Calibration System for an Acoustic Telemetry System

The Juvenile Salmon Acoustic Telemetry System (JSATS) is an active sensing technology developed by the U.S. Army Corps of Engineers, Portland District, for detecting and tracking small fish. It is used primarily for evaluating behavior and survival of juvenile salmonids migrating through the Federal Columbia River Power System to the Pacific Ocean. It provides critical data for salmon protection and development of more “fish-friendly” hydroelectric facilities. The objective of this study was to design and build a Measurement and Calibration System (MCS) for evaluating the JSATS components, because the JSATS requires comprehensive acceptance and performance testing in a controlled environment before it is deployed in the field. The MCS consists of a reference transducer, a water test tank lined with anechoic material, a motion control unit, a reference receiver, a signal conditioner and amplifier unit, a data acquisition board, MATLAB control and analysis interface, and a computer. The fully integrated MCS has been evaluated successfully at various simulated distances and using different encoded signals at frequencies within the bandwidth of the JSATS transmitter. The MCS provides accurate acoustic mapping capability in a controlled environment and automates the process that allows real-time measurements and evaluation of the piezoelectric transducers, sensors, or the acoustic fields. The MCS has been in use since 2009 for acceptance and performance testing of, and further improvements to, the JSATS

Digital Signal Processing

Contains research objectives and summary of research.National Science Foundation (Grant GK-31353)U. S. Navy Office of Naval Research (Contract N00014-67-A-0204-0064