A5011134257- Muon and positron interactions and applications
- Direction-of-Arrival Estimation Techniques
- Fusion materials and technologies
- Blind Source Separation Techniques
- Ion-surface interactions and analysis
- Radio Astronomy Observations and Technology
- Semiconductor materials and devices
- Nuclear Materials and Properties
- Speech and Audio Processing
- Antenna Design and Optimization
- Indoor and Outdoor Localization Technologies
- Silicon and Solar Cell Technologies
- Advanced Wireless Communication Techniques
- Wireless Communication Networks Research
- Advanced Adaptive Filtering Techniques
- Graphene research and applications
- Copper Interconnects and Reliability
- Matrix Theory and Algorithms
- Ultra-Wideband Communications Technology
- Advanced Materials Characterization Techniques
- Control Systems and Identification
- Metal and Thin Film Mechanics
- Millimeter-Wave Propagation and Modeling
- Nuclear Physics and Applications
- Antenna Design and Analysis
Delft University of Technology
2016-2025
Netherlands Institute for Radio Astronomy
2013
Istituto Nazionale di Ricerca Metrologica
2011
Stanford University
1996-2009
Technical University of Darmstadt
2007
University of Groningen
1990-2003
March of Dimes
2002
Materials innovation institute
1976-1994
Utrecht University
1972-1980
Rijksmuseum
1972
Iterative constant modulus algorithms such as Godard (1980) and CMA have been used to blindly separate a superposition of cochannel (CM) signals impinging on an antenna array. These certain deficiencies in the context convergence local minima retrieval all individual CM that are present channel. We show underlying factorization problem is, fact, generalized eigenvalue problem, may be solved via simultaneous diagonalization set matrices. With this new analytical approach, it is possible...
The program VEPFIT is presented which extrats the relevant parameters from positron measurements on implanted materials and layered structures. Measurements of Doppler Broadening parameter S positronium fraction F vs energy incident positrons are analyzed by means a semi‐linear fitting procedure. principles analysis method given performance artificially experimentally obtained data demonstrated. Fitting strategies outlined accuracy results discussed.
In multiple-input multiple-output (MIMO) systems, the use of many radio frequency (RF) and analog-to-digital converter (ADC) chains at receiver is costly. Analog beamformers operating in RF domain can reduce number antenna signals to a feasible baseband channels. Subsequently, digital beamforming used capture desired user signal. this paper, we consider design analog coefficients, for case narrowband signals. We aim cancel interfering domain, thus minimizing required ADC resolution. For...
A unified approach is presented to the related problems of recovering signal parameters from noisy observations and identifying linear system model observed input/output signals, both using singular value decomposition (SVD) techniques. Both known new SVD-based identification methods are classified in a subspace-oriented scheme. The SVD matrix constructed data provides key step robust discrimination between desired signals disturbing terms noise subspaces. that distinguished by way which...
In a multipath communication scenario, it is often relevant to estimate the directions and relative delays of each ray. We derive closed-form subspace-based method for simultaneous estimation these parameters from an estimated channel impulse response, using knowledge transmitted pulse shape function. The algorithm uses two-dimensional (2-D) ESPRIT-like shift-invariance technique separate phase shifts due delay direction incidence with automatic pairing two parameter sets. Improved...
In a parametric multipath propagation model, source is received by an antenna array via number of rays, each described arrival angle, delay, and fading parameter. Unlike the fading, angles delays are stationary over long time intervals. This fact exploited in new subspace-based high-resolution method for simultaneous estimation angle/delay parameters from multiple estimates channel impulse response. A computationally expensive optimization search can be avoided using ESPRIT-like algorithm....
The two key limiting factors facing wireless systems today are multipath interference and multiuser interference. In this context, a challenging signal processing problem is the joint space-time equalization of multiple digital signals transmitted over channels. We propose blind approach that does not use training sets to estimate channel. Instead, takes advantage spatial temporal oversampling techniques finite alphabet property determine user symbol sequences. channels with largely...
High-resolution parameter estimation techniques have been applied to jointly estimate multiple signal parameters. we consider the problem of determining directions and center frequencies a number narrowband sources in band interest. We present joint angle-frequency method, based on multidimensional ESPRIT algorithm. A perturbation error analysis gives bounds estimates provides optimal values for temporal spatial smoothing The is shown be consistent with simulation results.
A number of high-resolution direction finding methods for determining the two-dimensional DOA (directions arrival) a plane waves impinging on sensor array are discussed. The consists triplets sensors that identical, as an extension one-dimensional ESPRIT scenario to two dimensions. Algorithms yield correct parameter pairs while avoiding extensive search over separate sets devised.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Over the last two decades, radar-based contactless monitoring of vital signs (heartbeat and respiration rate) has raised increasing interest as an emerging added value to health care. However, until now, flaws caused by indoor multipath propagation formed a fundamental hurdle for adoption such technology in practical healthcare applications where reliability robustness are crucial. Multipath reflections, originated from one person, combine with direct signals multipaths other people...
Deterministic blind beamforming algorithms try to separate superpositions of source signals impinging on a phased antenna array by using the deterministic properties or channels such as their constant modulus directions-of-arrival. Progress in this area has been abundant over past ten years and resulted several powerful algorithms. Unlike optimal adaptive methods, algebraic methods discussed review act fixed block data give closed-form expressions for beamformers focusing structures. This...
Calibration of a sensor array is more involved if the antennas have direction dependent gains and multiple calibrator sources are simultaneously present. We study this case for with arbitrary geometry but identical elements, i.e. elements same gain pattern. A weighted alternating least squares (WALS) algorithm derived that iteratively solves independent complex their noise powers in sources. An extension problem where apparent source locations unknown, e.g., due to refractive propagation...
We aim to provide a critical appraisal of basic concepts underlying signal recording and processing technologies applied for (i) atrial fibrillation (AF) mapping unravel AF mechanisms and/or identifying target sites therapy (ii) detection, optimize usage technologies, stimulate research aimed at closing knowledge gaps, developing ideal technologies. Recording techniques assessment electrical activity during essential diagnosis guiding ablative including body surface electrocardiograms (ECG)...
Radio-astronomical observations are increasingly corrupted by RF interference, and online detection filtering algorithms becoming essential.To facilitate the introduction of such techniques into radio astronomy, we formulate astronomical problem in an array signal processing language, give to some elementary from that field.We consider two topics detail: interference rank estimation short-term covariance matrices, spatial subspace projection.We discuss experimental data collected at...
Joint diagonalization problems of Hermitian or non-Hermitian matrices occur as the final parameter estimation step in several blind source separation such ACMA, JADE, PARAFAC, and SOBI. Previous approaches have been Jacobi iteration schemes alternating projections. Here we show how joint problem can be formulated a (weighted) subspace fitting so that it solved using efficient Gauss-Newton optimization algorithm proposed for problem. Since good initial point is usually available, converges very fast.
An improved approach is presented for the analysis of positron beam Doppler broadening data. Instead analyzing energy-dependent shape parameter, so-called S(E) data, we combined and wing W(E) data by plotting them as a trajectory in S–W plane, using implantation energy running parameter. It shown that this plot particular interest qualitative interpretation Furthermore, it allows independent determination characteristic parameters different trapping layers without use numerical simulation...
Using oversampling and the finite-alphabet property of digital communication signals, it is possible to blindly identify an FIR channel carrying a superposition such provided they have same (known) period, certain rank conditions on data matrices are satisfied. In particular, this technique allows separation finite alphabet removal intersymbol interference, synchronization signals. An algorithm proposed tested simulated data.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...
LOFAR is a low-frequency radio astronomical array currently under development in The Netherlands. It designed to produce synthesis images of the most distant celestial objects yet observed. Due high redshift levels, observations must be at unusually low frequencies (30-240 MHz), over large apertures (100 km), using thousands antennas. At these frequencies, Earth's ionosphere acts as random refractive sheet which aperture induces source direction dependent gain and phase errors that estimated...