Signal Subspace Processing in the Beam Space of a True Time Delay Beamformer Bank

A number of techniques for Radio Frequency (RF) source location for wide bandwidth signals have been described that utilize coherent signal subspace processing, but often suffer from limitations such as the requirement for preliminary source location estimation, the need to apply the technique iteratively, computational expense or others. This dissertation examines a method that performs subspace processing of the data from a bank of true time delay beamformers. The spatial diversity of the beamformer bank alleviates the need for a preliminary estimate while simultaneously reducing the dimensionality of subsequent signal subspace processing resulting in computational efficiency. The pointing direction of the true time delay beams is independent of frequency, which results in a mapping from element space to beam space that is wide bandwidth in nature. This dissertation reviews previous methods, introduces the present method, presents simulation results that demonstrate the assertions, discusses an analysis of performance in relation to the Cramer-Rao Lower Bound (CRLB) with various levels of noise in the system, and discusses computational efficiency. One limitation of the method is that in practice it may be appropriate for systems that can tolerate a limited field of view. The application of Electronic Intelligence is one such application. This application is discussed as one that is appropriate for a method exhibiting high resolution of very wide bandwidth closely spaced sources and often does not require a wide field of view. In relation to system applications, this dissertation also discusses practical employment of the novel method in terms of antenna elements, arrays, platforms, engagement geometries, and other parameters. The true time delay beam space method is shown through modeling and simulation to be capable of resolving closely spaced very wideband sources over a relevant field of view in a single algorithmic pass, requiring no course preliminary estimation, and exhibiting low computational expense superior to many previous wideband coherent integration techniques

Signal Subspace Processing in the Beam Space of a True Time Delay Beamformer Bank

A number of techniques for Radio Frequency (RF) source location for wide bandwidth signals have been described that utilize coherent signal subspace processing, but often suffer from limitations such as the requirement for preliminary source location estimation, the need to apply the technique iteratively, computational expense or others. This dissertation examines a method that performs subspace processing of the data from a bank of true time delay beamformers. The spatial diversity of the beamformer bank alleviates the need for a preliminary estimate while simultaneously reducing the dimensionality of subsequent signal subspace processing resulting in computational efficiency. The pointing direction of the true time delay beams is independent of frequency, which results in a mapping from element space to beam space that is wide bandwidth in nature. This dissertation reviews previous methods, introduces the present method, presents simulation results that demonstrate the assertions, discusses an analysis of performance in relation to the Cramer-Rao Lower Bound (CRLB) with various levels of noise in the system, and discusses computational efficiency. One limitation of the method is that in practice it may be appropriate for systems that can tolerate a limited field of view. The application of Electronic Intelligence is one such application. This application is discussed as one that is appropriate for a method exhibiting high resolution of very wide bandwidth closely spaced sources and often does not require a wide field of view. In relation to system applications, this dissertation also discusses practical employment of the novel method in terms of antenna elements, arrays, platforms, engagement geometries, and other parameters. The true time delay beam space method is shown through modeling and simulation to be capable of resolving closely spaced very wideband sources over a relevant field of view in a single algorithmic pass, requiring no course preliminary estimation, and exhibiting low computational expense superior to many previous wideband coherent integration techniques

Sensor array signal processing : two decades later

Caption title.Includes bibliographical references (p. 55-65).Supported by Army Research Office. DAAL03-92-G-115 Supported by the Air Force Office of Scientific Research. F49620-92-J-2002 Supported by the National Science Foundation. MIP-9015281 Supported by the ONR. N00014-91-J-1967 Supported by the AFOSR. F49620-93-1-0102Hamid Krim, Mats Viberg

Signal Processing and Propagation for Aeroacoustic Sensor Networking,” Ch

Passive sensing of acoustic sources is attractive in many respects, including the relatively low signal bandwidth of sound waves, the loudness of most sources of interest, and the inherent difficulty of disguising or concealing emitted acoustic signals. The availability of inexpensive, low-power sensing and signal-processing hardware enables application of sophisticated real-time signal processing. Among th

Direction of arrival estimation of WiMedia UWB multipath signals in the presence of inband interferers

Ph.DDOCTOR OF PHILOSOPH

High-resolution Direction-of-Arrival estimation

Direction of Arrival (DOA) estimation is considered one of the most crucial problems in array signal processing, with considerable research efforts for developing efficient and effective direction-finding algorithms, especially in the transportation industry, where the demand for an effective, real-time, and accurate DOA algorithm is increasing. However, challenges must be addressed before real-world deployment can be realised. Firstly, there is the requirement for fast computational time for real-time detection. Secondly, there is a demand for high-resolution and accurate DOA estimation. In this thesis, two state-of-the-art DOA estimation algorithms are proposed and evaluated to address the challenges. Firstly, a novel covariance matrix reconstruction approach for single snapshot DOA estimation (CbSS) was proposed. CbSS was developed by exploiting the relationship between the theoretical and sample covariance matrices to reduce estimation error for a single snapshot scenario. CbSS can resolve accurate DOAs without requiring lengthy peak searching computational time by computationally changing the received sample covariance matrix. Simulation results have verified that the CbSS technique yields the highest DOA estimation accuracy by up to 25.5% compared to existing methods such as root-MUSIC and the Partial Relaxation approach. Furthermore, CbSS presents negligible bias when compared to the existing techniques in a wide range of scenarios, such as in multiple uncorrelated and coherent signal source environments. Secondly, an adaptive diagonal-loading technique was proposed to improve DOA estimation accuracy without requiring a high computational load by integrating a modified novel and adaptive diagonal-loading method (DLT-DOA) to further improve estimation accuracy. An in-depth simulation performance analysis was conducted to address the challenges, with a comparison against existing state-of-the-art DOA estimation techniques such as EPUMA and MODEX. Simulation results verify that the DLT-DOA technique performs up to 8.5% higher DOA estimation performance in terms of estimation accuracy compared to existing methods with significantly lower computational time. On this basis, the two novel DOA estimation techniques are recommended for usage in real-world scenarios where fast computational time and high estimation accuracy are expected. Further research is needed to identify other factors that could further optimize the algorithms to meet different demands

Direction-Of-Arrival Estimation Using Multiple Sensors

Ph.DDOCTOR OF PHILOSOPH

Localization and Tracking in Wireless MIMO Systems

Ph.DDOCTOR OF PHILOSOPH

Compact adaptive planar antenna arrays for robust satellite navigation systems

In den zurückliegenden zwei Jahrzehnten ist die Abhängigkeit der Industriegesellschaft von satellitengestützten Ortungssystemen, Navigationsdiensten und Zeitsignalen dramatisch gewachsen. Darauf aufbauende moderne Anwendungen reichen von hochgenauen Ortungsgeräten bis zu intelligenten Transportsystemen und von der Synchronisation mobiler Netzwerke zu Wetter- und Klimabeobachtung. Dies setzt neue höhere Standards in der Robustheit, Genauigkeit, Verfügbarkeit und Verlässlichkeit moderner Navigationsempfänger voraus. Möglich werden diese Verbesserungen aktuell mit der Einführung von Multiantennensystemen in den Navigationsgeräten. Jedoch wird die Nutzung dieses Ansatzes durch die größeren Abmessungen der Antennenarrays erschwert, weil standardmäßig der Elementabstand zu einer halben Freiraumwellenlänge gewählt wird, was im L Band ca. 10 cm bedeutet. In dieser Arbeit werden kompakte Antennenarrays für Navigationsempfänger mit geringerem Elementabstand vorgeschlagen, die eine Miniaturisierung der Empfängerabmessungen erlauben. Diese kompakten Arrays werden in ihrer Leistungsfähigkeit jedoch durch die negativen Effekte der Verkopplung zwischen den Einzelelementen beeinträchtigt. Für die Beurteilung der Empfängerleistungsfähigkeit existieren verschiedene Qualitätsparameter für Analyse und Entwurf der planaren Arrays. Damit werden z. B. Diversity Freiheitsgrade, Qualität der Richtungsschätzung, Polarisationsreinheit und die wechselseitigen Kopplungen gemessen und eine Entwurfsumgebung wird vorgestellt, in der das optimale kompakte Antennenarray für den jeweiligen Einsatzzweck ausgewählt und konfiguriert werden kann. Dieser Prozess wird durch eine Analyse des Rauschens und seiner Korrelationseigenschaften für den gesamten Empfänger begleitet. Darüber hinaus wird ein analytisches Modell des effektiven carrier-to-interference-plus-noise ratio abgeleitet, um die Leistungsfähigkeit der Navigationsempfänger in Szenarien mit Störsignalen zu untersuchen. Schließlich werden diese Betrachtungen durch den Aufbau eines kompletten Satellitennavigationsempfängers ergänzt, um mit ihm den Nachweis der Funktionsfähigkeit und der stabilen Funktion des entworfenen Systems mit kompaktem Array unter Störereinfluss bei Laborbedingungen und in den reale Außeneinsatz zu erbringen.Over the past two decades, humankind's reliance on global navigation satellite systems for precise positioning, navigation and timing services has grown remarkably. Such advanced applications vary from highly accurate surveying to intelligent transport systems, and from mobile network timing synchronization to weather and climate monitoring. This envisages new and higher standards of robustness, accuracy, coverage and integrity in modern navigation receivers. Recently, this has been accomplished with the incorporation of the multi-element navigation antenna receiver. However, the industrialization of this approach is limited due to the large antenna array size, hindered by the inter-element separation of half of the free-space wavelength, i.e. ≈ 10 cm at L band 1-2 GHz. In this thesis, compact navigation antenna arrays with smaller inter-element separations are proposed for the miniaturization of the overall size. However, these arrays become afflicted with the adverse effects of mutual coupling. Therefore, various figures-of-merit for the analysis and design of a compact planar navigation antenna array, such as performance diversity degrees-of-freedom, directional finding capabilities, and polarization purity, including mutual coupling effects, have been presented. This provides a general framework for the selection and configuration of the optimum compact navigation antenna array. In order to mitigate the mutual coupling, integration of the decoupling and matching network into customized compact navigation antenna array designs is performed. This is fostered by the correlated noise characterization of the complete receiver. Furthermore, an analytical model of the equivalent carrier-to-interference-plus-noise ratio is derived to investigate the navigation performance in interference scenarios. In the end, this is complemented by the implementation of the complete navigation receiver for verification and robustness validation of the derived compact antenna array concepts in indoor and outdoor interference scenarios