1. Basic Concepts. 2. Nonparametric Methods. 3. Parametric Methods for Rational Spectra. 4. Parametric Methods for Line Spectra. 5. Filter Bank Methods. 6. Spatial Methods. Appendix A: Linear Algebra and Matrix Analysis Tools. Appendix B: Cramer-Rao Bound Tools. Appendix C: Model Order Selection Tools. Appendix D: Answers to Selected Exercises. Bibliography. References Grouped by Subject. Subject Index.

/pdf/spectral-analysis-of-signals-4dbupf9m4n.pdf

Spectral analysis of signals

We consider the problem of locating and orienting a network of unattended sensor nodes that have been deployed in a scene at unknown locations and orientation angles. This self-calibration problem is solved by placing a number of source signals, also with unknown locations, in the scene. Each source in turn emits a calibration signal, and a subset of sensor nodes in the network measures the time of arrival and direction of arrival (with respect to the sensor node's local orientation coordinates) of the signal emitted from that source. From these measurements we compute the sensor node locations and orientations, along with any unknown source locations and emission times. We develop necessary conditions for solving the self-calibration problem and provide a maximum likelihood solution and corresponding location error estimate. We also compute the Cramer-Rao bound of the sensor node location and orientation estimates, which provides a lower bound on calibration accuracy. Results using both synthetic data and field measurements are presented.

/pdf/a-self-localization-method-for-wireless-sensor-networks-38oq6a92ev.pdf

A Self-Localization Method for Wireless Sensor Networks

Multi-rate asynchronous sub-Nyquist sampling (MASS) is proposed for wideband spectrum sensing. Corresponding spectral recovery conditions are derived and the probability of successful recovery is given. Compared to previous approaches, MASS offers lower sampling rate, and is an attractive approach for cognitive radio networks.

Wideband Spectrum Sensing With Sub-Nyquist Sampling in Cognitive Radios

Field biologists use animal sounds to discover the presence of individuals and to study their behavior. Collecting bio- acoustic data has traditionally been a difficult and time- consuming process in which researchers use portable microphones to record sounds while taking notes of their own detailed observations. The recent development of new deploy- able acoustic sensor platforms presents opportunities to develop automated tools for bio-acoustic field research. In this work, we implement an AML-based source localization algorithm, and use it to localize marmot alarm-calls. We assess the performance of these techniques based on results from two field experiments: (1) a controlled test of direction-of- arrival (DOA) accuracy using a pre-recorded source signal, and (2) an experiment to detect and localize actual animals in their habitat, with a comparison to ground truth gathered from human observations. Although small arrays yield ambiguities from spatial aliasing of high frequency signals, we show that these ambiguities are readily eliminated by proper bearing crossings of the DOAs from several arrays. These results show that the AML source localization algorithm can be used to localize actual animals in their natural habitat, using a platform that is practical to deploy.

/pdf/an-empirical-study-of-collaborative-acoustic-source-25rx2a77uq.pdf

An empirical study of collaborative acoustic source localization

An accurate dynamic ultrasonic hybrid localization system is presented for autonomous navigation of indoor mobile robots using multiple ultrasonic distance measurements and an extended Kalman filter (EKF). The ultrasonic sensor subsystem is composed of several ultrasonic transmitters (Txs) attached to the ceiling at known positions and several ultrasonic receivers equilaterally located on the top of the mobile robot, which has a moving speed that is not negligible. An EKF-based algorithm with a state/observation vector composed of the robot pose (or the position and the orientation) is presented using odometric and ultrasonic distance measurements. A dynamic distance estimation method is proposed to track the estimates of ultrasonic distance information from available Txs of interest using both odometric information from the robot and actual ultrasonic distance measurements. This continuous dynamic distance estimation allows persistent use of the hybrid self-localization algorithm to accurately determine the pose of the robot. The experimental results with various trajectories clearly show that the proposed method is much more accurate than only the hybrid self-localization algorithm (without the dynamic distance estimation method).

Dynamic Ultrasonic Hybrid Localization System for Indoor Mobile Robots

We consider array geometries whose direction-of-arrival (DOA) estimation performance is isotropic. An isotropic array is one whose Cramer-Rao bound (CRB) on the DOA of a single source is uniform for all angles. For both planar arrays and volume arrays we derive necessary and sufficient conditions on array element locations so that the array is isotropic. We also present several designs of isotropic planar and volume arrays. The results apply to both narrowband and wideband scenarios. We analyze the special case where a planar array is used to estimate the DOA of three-dimensional (3-D) source. Finally, we compare isotropic array performance to the best possible array performance.

/pdf/on-the-geometry-of-isotropic-arrays-2wutmqc5p7.pdf

On the geometry of isotropic arrays

We consider the role of array geometry on the Direction of Arrival (DOA) estimating performance of the array where the impinging signal is wideband. We define the criteria under which the planar and volume arrays are isotropic, and derive the necessary and sufficient conditions on the location of array elements so that the array has isotropic performance. We also present several designs of isotropic planar and volume arrays and give example geometries.

On the geometry of isotropic wideband arrays

: We consider the role of array geometry on the Direction of Arrival (DOA) estimating performance of the array where the impinging signal is wideband We concentrate on arrays that have isotropic performance An isotropic array is one whose Cramer Rao bound (CRB) on the DOA of a single source is uniform for all angles We derive the necessary and sufficient conditions on the location of array elements so that the array is isotropic Both planar arrays and three dimensional arrays are considered We also present several designs of isotropic planar and volume arrays and give example geometries

/pdf/optimal-array-geometries-for-wideband-doa-estimation-4x4ei6luv1.pdf

Ulku Baysal

Papers

On the geometry of isotropic arrays

On the geometry of isotropic wideband arrays

Optimal Array Geometries for Wideband DOA Estimation