International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The expectation-maximization (EM) algorithm is well established as a computationally efficient method for separable signal parameter estimation. Here, a new geometric derivation and interpretation of the EM algorithm is given that facilitates the understanding of its convergence properties. Geometric considerations then lead to an alternative separable signal parameter estimator based on successive cancellation. The new Generalized Successive Interference Cancellation (GSIC) algorithm may offer better performance than EM in the presence of large signal power disparities. Finally, application of the GSIC algorithm to CDMA-based radiolocation is discussed, and simulation results are presented.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

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<p>Shooter localization systems are used to detect and locate the origin of gunfire. A wireless sensor network is one possible implementation of such a system. A wireless sensor network is sensitive to synchronization errors. Localization techniques that rely on the timing will give less accurate or even useless results if the synchronization errors are too large.</p><p>This thesis focuses on the influence of synchronization errors on the abilityto localize a shooter using a wireless sensor network. A localization algorithm</p><p>is developed and implemented and the effect of synchronization errors is studied. The localization algorithm is evaluated using numerical experiments, simulations, and data from real gunshots collected at field trials.</p><p>The results indicate that the developed localization algorithm is able to localizea shooter with quite good accuracy. However, the localization performance is to a high degree influenced by the geographical configuration of the network as well as the synchronization error.</p> / <p><p>Skottlokaliseringssystem används för att upptäcka och lokalisera ursprunget för avlossade skott. Ett trådlöst sensornätverk är ett sätt att utforma ett sådant system.Trådlösa sensornätverk är känsliga för synkroniseringsfel. Lokaliseringsmetoder som bygger på tidsobservationer kommer med för stora synkroniseringsfel ge dåliga eller helt felaktiga resultat.</p><p>Detta examensarbete fokuserar på vilken inverkan synkroniseringsfel har på möjligheterna att lokalisera en skytt i ett trådlöst sensornätverk. En lokaliseringsalgoritm utvecklas och förmågan att korrekt lokalisera en skytt vid olika synkroniseringsfel undersöks. Lokaliseringsalgoritmen prövas med numeriska experiment, simuleringar och även för data från riktiga skottljud, insamlade vid fältförsök.</p><p>Resultaten visar att lokaliseringsalgoritmen fungerar tillfredställande, men att lokaliseringsförmågan till stor del påverkas av synkroniseringsfel men även av sensornätverkets geografiska utseende.</p></p>

Since smart homes will be more and more popular in the future, the needs of finding a friendly, comfortable and smart interface between users and home environments are growing. However, conventional interfaces have reached their limits. So, this paper describes a new concept of interface in a home environment. This work is distinguished by building a separable smart robot. A smart phone is used as a brain, and a robot car is used as a body. With the system, people will be allowed to carry the robot's brain when they are out of their home. In this case, the brain can not only be a normal smart phone, but also can monitor parameters such as the temperature at home. On the other hand, when people are at home, they will be allowed to put their phones on the robot car. By invoking the system, they will have an assist-robot. This assist-robot will act as a new interface in the smart home by following people and recognizing their voice commands in order to take notes, to read notes and to control smart home devices. This thesis also implements face recognition to improve the communication between users and the interface. Test results show that our proposed system is well accepted.

Abstract In time delay estimation the correlator or, equivalently, matched filter estimator is widely used. Examples of its usage can be found in the global positioning system (GPS), radars and code division multiple access (CDMA) communication systems. Although widely used its performance is not studied in general case until recently. Partially this study is done in this thesis. If interfering signals like multipath or multiple access signals exist in addition to additive white Gaussian noise, as in GPS and CDMA, the correlator is not a maximum likelihood (ML) estimator. However, it is known that the correlator produces consistent estimates in the existence of multipath interference if the delay separation is larger than the correlation time of the signal (in direct sequence spread spectrum applications such as GPS and CDMA, the correlation time approximately equals the chip duration of the spreading code). It also performs well in the existence of multiple access interference (MAI), if the powers of the MAI signals are equal to the power of the desired signal. In this thesis the asymptotic distribution of the correlator estimator is derived in multisignal environments. Using the result, it can be analytically shown, that in these benign interference cases the exact ML estimator and the correlator estimators perform equally well in the sense that their asymptotic covariance matrices are equal. The thesis also verifies the well known result that if the signals are orthogonal, then the correlator and ML estimators perform equally. In addition, the correlator's asymptotic performance is investigated also in the inconsistent case by slightly extending the earlier results found in the literature. Also the resolution of the correlator estimator is investigated. It is numerically shown that the correlator estimator can produce consistent estimators even if the delay separation is less that the chip duration, which is commonly believed to be the resolution limit of the correlator. This can happen in fading channels where the multipath amplitudes are uncorrelated or just slightly correlated. This result seems to be fairly unknown. In addition to the classical ML estimator, where all the unknowns are assumed to be deterministic, also an improved ML estimator is investigated. This other ML estimator is obtained by assuming that the amplitudes are Gaussian distributed. It is an improved estimator in the sense that its asymptotic covariance, say CML, is less positive definite than that of the classical ML estimator CCML, i.e., CCML-CML is positive semidefinite. More importantly, this result is valid independent of the fact are the amplitudes really deterministic or Gaussian. This well known result is shown in this thesis to be valid also if the signals contain more than one unknown parameter, which occurs, for example, in direction-of-arrival estimation when two angles per arrival are to be estimated.

Since smart homes will be more and more popular in the future, the needs of finding a friendly, comfortable and smart interface between users and home environments are growing. However, conventional interfaces have reached their limits. So, this paper describes a new concept of interface in a home environment. This work is distinguished by building a separable smart robot. A smart phone is used as a brain, and a robot car is used as a body. With the system, people will be allowed to carry the robot's brain when they are out of their home. In this case, the brain can not only be a normal smart phone, but also can monitor parameters such as the temperature at home. On the other hand, when people are at home, they will be allowed to put their phones on the robot car. By invoking the system, they will have an assist-robot. This assist-robot will act as a new interface in the smart home by following people and recognizing their voice commands in order to take notes, to read notes and to control smart home devices. This thesis also implements face recognition to improve the communication between users and the interface. Test results show that our proposed system is well accepted.

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<p> We study the Coulomb effect on the proton-proton low-energy scattering parameters when all other effects are represented by a separable potential.</p> <p> For this purpose, we present a formulation for the scattering of two particles via a separable potential. We treat the same problem when any potential, particularly a Coulomb potential or a separable potential, is added to the separable potential. The properties of scattering from a separable potential plus a (local or non-local) potential lead us to the possibility of obtaining a one term separable potential equivalent to a two term separable potential, and a model for the nuclear potential as a sum of a separable potential and a non-separable potential.</p> <p> We determine, to the first order in Me^2/β where β^-1 is the range of the separable potential, the parameters for Yamaguchi's and Naqvi's separable potentials from proton-proton scattering data. We use these parameters to calculate the low-energy proton-proton scattering parameters when the Coulomb interaction is removed. Our results show that the shape dependence of these parameters are somewhat larger than obtained by Heller et al in their investigation on local potentials. Implications of our results concerning the charge symmetry and charge independence of the nuclear forces are discussed.</p> / Thesis / Master of Science (MSc)

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