Real-Time Bearing Estimation in a Multi-Source Environment Using Multi-Processor, Multi-Algorithmic Acceleration

Electrical Engineerin

Combined-channel instantaneous frequency analysis for audio source separation based on comodulation

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2008.Includes bibliographical references (p. 295-303).Normal human listeners have a remarkable ability to focus on a single sound or speaker of interest and to block out competing sound sources. Individuals with hearing impairments, on the other hand, often experience great difficulty in noisy environments. The goal of our research is to develop novel signal processing methods inspired by neural auditory processing that can improve current speech separation systems. These could potentially be of use as assistive devices for the hearing impaired, and in many other communications applications. Our focus is the monaural case where spatial information is not available. Much perceptual evidence indicates that detecting common amplitude and frequency variation in acoustic signals plays an important role in the separation process. The physical mechanisms of sound generation in many sources cause common onsets/offsets and correlated increases/decreases in both amplitude and frequency among the spectral components of an individual source, which can potentially serve as a distinct signature. However, harnessing these common modulation patterns is difficult because when spectral components of competing sources overlap within the bandwidth of a single auditory filter, the modulation envelope of the resultant waveform resembles that of neither source. To overcome this, for the coherent, constant-frequency AM case, we derive a set of matrix equations which describes the mixture, and we prove that there exists a unique factorization under certain constraints. These constraints provide insight into the importance of onset cues in source separation. We develop algorithms for solving the system in those cases in which a unique solution exists. This work has direct bearing on the general theory of non-negative matrix factorization which has recently been applied to various problems in biology and learning. For the general, incoherent, AM and FM case, the situation is far more complex because constructive and destructive interference between sources causes amplitude fluctuations within channels that obscures the modulation patterns of individual sources.(cont.) Motivated by the importance of temporal processing in the auditory system, and specifically, the use of extrema, we explore novel methods for estimating instantaneous amplitude, frequency, and phase of mixtures of sinusoids by comparing the location of local maxima of waveforms from various frequency channels. By using an overlapping exponential filter bank model with properties resembling the cochlea, and combining information from multiple frequency bands, we are able to achieve extremely high frequency and time resolution. This allows us to isolate and track the behavior of individual spectral components which can be compared and grouped with others of like type. Our work includes both computational and analytic approaches to the general problem. Two suites of tests were performed. The first were comparative evaluations of three filter-bank-based algorithms on sets of harmonic-like signals with constant frequencies. One of these algorithms was selected for further performance tests on more complex waveforms, including AM and FM signals of various types, harmonic sets in noise, and actual recordings of male and female speakers, both individual and mixed. For the frequency-varying case, initial results of signal analysis with our methods appear to resolve individual sidebands of single harmonics on short time scales, and raise interesting conceptual questions on how to define, use and interpret the concept of instantaneous frequency. Based on our results, we revisit a number of questions in current auditory research, including the need for both rate and place coding, the asymmetrical shapes of auditory filters, and a possible explanation for the deficit of the hearing impaired in noise.by Barry David Jacobson.Ph.D

Electric load information system based on non-intrusive power monitoring

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (leaves 192-200).Obtaining high quality information economically and reliably is always a difficult objective to achieve. The electric power industry and consumers recently face many challenges, such as deregulation, autonomous power systems and power quality. The knowledge of the nature and state of the power systems will undoubtedly be the key in meeting these challenges. The Non-Intrusive Power Monitor is a novel attempt to collect such information with a minimal physical installation. Raw voltage and current are measured at a single location to yield harmonic power signals. They typically carry the fingerprints of the electric loads present in a system, and their analysis can produce such information as the operational and diagnostic status of the loads. The power signals can also be used for the system identification, parameter estimation and energy consumption optimization study. In this research, the power signals are mostly modeled as stochastic processes and various detection, estimation and pattern recognition algorithms are developed to extract desired information. A constant load status identifier is developed in this thesis which can identify the ON and OFF status of electric loads, both from their steady-state power consumptions and transient patterns. The identifier can also classify multiple load events occurring at a same time and estimate states without load events. The power consumed by a variable speed drive is also estimated using the correlations between the fundamental powers and higher harmonic powers. The harmonic signal generated by the imbalance of a rotating machine is estimated to monitor the drive, i.e. its speed and magnitude of the imbalance. The algorithms are thoroughly tested using the data collected at real buildings, and some of them are implemented on-line.(cont.) This thesis focuses on developing mathematical models and signal processing algorithms for the customers at the end of the AC distribution system. Its results will directly benefit the developments of a ubiquitous electric meter in a deregulated market, a diagnostic or prognostic tool for mission-critical systems and an intelligent power quality monitor.by Kwangduk Douglas Lee.Ph.D

A pre-filtering maximum likelihood approach to multiple source direction estimation.

Imperial Users onl

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion