Signal Processing Commons^™

Side Lobe Level Reduction And Array Thinning Of Concentric Circular Antenna Arrays, Alzahraa H. Nosier, Ahmed M. Elkhawaga, Mohamed E. Nasr, Nessim M. Mahmoud, Amr H. Hussein

Mansoura Engineering Journal

This paper presents a new beamforming technique based on the hybrid combination of the convolution algorithm (CA) and the genetic algorithm (GA) for reducing side lobe level (SLL) and array thinning of concentric circular antenna arrays (CCAA), which is denoted as C/GA technique. The CA determines the excitations of the elements, while the GA optimizes the radii of the circular arrays to adjust the half-power beamwidth (HPBW). For CCAA consisting of uniform feeding circular arrays, we assume that there are excitation coefficients that are distributed symmetrically around the array center and arranged in a vector. The excitation vector is convolved …

Adaptive Gps Antenna Array Beam Nulling Effectiveness Under Varying Antenna Element Positioning, Aadesh Neel

Electrical and Computer Engineering ETDs

Global Positioning System (GPS) is an essential part of modern life but is susceptible to same frequency jamming. GPS jamming can add excessive noise to a received low power signal and have the capability to change or completely distort information being sent through the GPS signal. Adaptive antenna arrays have long since been a solution to mitigating GPS jamming via beamnulling algorithms. However, there is little research on the effectiveness of these beamnulling algorithms under varying element positioning. In this work, an adaptive antenna array, consisting of Right-Hand Circularly Polarized (RHCP) nearly square GPS antenna elements, was constructed and tested …

Exploitation Of Robust Aoa Estimation And Low Overhead Beamforming In Mmwave Mimo System, Yuyan Zhao

Electronic Thesis and Dissertation Repository

The limited spectral resource for wireless communications and dramatic proliferation of new applications and services directly necessitate the exploitation of millimeter wave (mmWave) communications. One critical enabling technology for mmWave communications is multi-input multi-output (MIMO), which enables other important physical layer techniques, specifically beamforming and antenna array based angle of arrival (AoA) estimation. Deployment of beamforming and AoA estimation has many challenges. Significant training and feedback overhead is required for beamforming, while conventional AoA estimation methods are not fast or robust. Thus, in this thesis, new algorithms are designed for low overhead beamforming, and robust AoA estimation with significantly reduced …

Performance Simulation And Optimization Of A Simultaneous Transmit And Receive Phased Antenna Array Using Adaptive Beamforming And Genetic Algorithm Techniques, Ian Thomas Cummings

Dissertations, Master's Theses and Master's Reports

The development of simultaneous transmit and receive capabilities is on the cutting-edge of research in phased array technology [1, 2, 3]. The large disparity in power between the transmitted and received signals in antenna systems has traditionally prevented operation in a simultaneous mode. However, simultaneous transmit and receive offers great opportunities for increased capabilities and performance in communications, radar, and electronic warfare applications [3]. This technology will be made feasible by realizing a high level of isolation between the transmitted and received signals through a variety of techniques. This work explores the feasibility of choosing non-standard array partitions that--when paired …

Time-Frequency Masking Performance For Improved Intelligibility With Microphone Arrays, Joshua P. Morgan

Theses and Dissertations--Electrical and Computer Engineering

Time-Frequency (TF) masking is an audio processing technique useful for isolating an audio source from interfering sources. TF masking has been applied and studied in monaural and binaural applications, but has only recently been applied to distributed microphone arrays. This work focuses on evaluating the TF masking technique's ability to isolate human speech and improve speech intelligibility in an immersive "cocktail party" environment. In particular, an upper-bound on TF masking performance is established and compared to the traditional delay-sum and general sidelobe canceler (GSC) beamformers. Additionally, the novel technique of combining the GSC with TF masking is investigated and its …

A Comparison Of Wavelet And Simplicity-Based Heart Sound And Murmur Segmentation Methods, Joshua David Korven

Master's Theses

Stethoscopes are the most commonly used medical devices for diagnosing heart conditions because they are inexpensive, noninvasive, and light enough to be carried around by a clinician. Auscultation with a stethoscope requires considerable skill and experience, but the introduction of digital stethoscopes allows for the automation of this task. Auscultation waveform segmentation, which is the process of determining the boundaries of heart sound and murmur segments, is the primary challenge in automating the diagnosis of various heart conditions. The purpose of this thesis is to improve the accuracy and efficiency of established techniques for detecting, segmenting, and classifying heart sounds …

Optimal Basis For Ultrasound Rf Apertures: Applications To Real-Time Compression And Beamforming, Sharmin Kibria

Masters Theses 1911 - February 2014

Modern medical ultrasound machines produce enormous amounts of data, as much as several gigabytes/sec in some systems. The challenges of generating, storing, processing and reproducing such voluminous data has motivated researchers to search for a feasible compression scheme for the received ultrasound radio frequency (RF) signals. Most of this work has concentrated on the digitized data available after sampling and A/D conversion. We are interested in the possibility of compression implemented directly on the received analog RF signals; hence, we focus on compression of the set of signals in a single receive aperture. We first investigate the model-free approaches to …

Microphone Array Optimization In Immersive Environments, Jingjing Yu

Theses and Dissertations--Electrical and Computer Engineering

The complex relationship between array gain patterns and microphone distributions limits the application of traditional optimization algorithms on irregular arrays, which show enhanced beamforming performance for human speech capture in immersive environments. This work analyzes the relationship between irregular microphone geometries and spatial filtering performance with statistical methods. Novel geometry descriptors are developed to capture the properties of irregular microphone distributions showing their impact on array performance. General guidelines and optimization methods for regular and irregular array design are proposed in immersive (near-field) environments to obtain superior beamforming ability for speech applications. Optimization times are greatly reduced through the objective …

Noise Reduction With Microphone Arrays For Speaker Identification, Zachary Gideon Cohen

Master's Theses

The presence of acoustic noise in audio recordings is an ongoing issue that plagues many applications. This ambient background noise is difficult to reduce due to its unpredictable nature. Many single channel noise reduction techniques exist but are limited in that they may distort the desired speech signal due to overlapping spectral content of the speech and noise. It is therefore of interest to investigate the use of multichannel noise reduction algorithms to further attenuate noise while attempting to preserve the speech signal of interest.

Specifically, this thesis looks to investigate the use of microphone arrays in conjunction with multichannel …

Effects Of Channel Mismatches On Beamforming And Signal Detection, Christopher I. Allen

Theses and Dissertations

Tuner gain measurements of a multichannel receiver are reported. A linear regression model is used to characterize the gain, as a function of channel number, tuner set-on frequency, and intermediate frequency. Residual errors of this model are characterized by a t distribution. Very strong autocorrelation of tuner gain at various frequencies is noted. Tuner performance from one channel to the next is diverse; several defects at specific frequencies are noted. The Wilcoxon signed rank test is used to test normality of tuner gain among devices; normality is rejected. Antenna directivity and phase pattern measurements are also reported. An antenna element …

Combined Beamforming And Space-Time Block Coding With A Sparse Array Antenna, Robert H. Morelos-Zaragoza, Mohammad Ghavami

Robert Henry Morelos-Zaragoza

In this paper, we continue our investigation of joint beamforming and transmit diversity with space-time block coding. In particular, the performance of a four-element array antenna is considered, in the context of an indoor wireless communication system. The main contribution is to show that transmit diversity may be practically achieved, even with correlated beams produced by a sparse array antenna.

Combined Beamforming And Space-Time Block Coding With Sparse Array Antennas, Robert H. Morelos-Zaragoza

Robert Henry Morelos-Zaragoza

In this paper, the combination of beamforming and space-time block coding is investigated. An adaptive scheme for the assignment of transmission beams is proposed. Data for the determination of beams are obtained using a triangular switch-beam array antenna at the transmitter. The number of peak points is determined from the data and a prescribed threshold level. Orthogonal space-time block coding is then applied to the transmission beams. We examine the distribution of the number of assigned beams as a function of indoor wireless channel parameters. Also, the effects of a small number of array elements and associated correlated beams, and …