Searched for: author:"Van der Veen, A.J."
(1 - 20 of 99)

Pages

document
van der Veen, A.J. (author), Wijnholds, SJ (author), Mouri Sardarabadi, A. (author)
Radio astronomy is known for its very large telescope dishes but is currently making a transition towards the use of a large number of small antennas. For example, the Low Frequency Array, commissioned in 2010, uses about 50 stations each consisting of 96 low band antennas and 768 or 1536 high band antennas. The low-frequency receiving system...
book chapter 2019
document
Rajan, R.T. (author), Leus, G.J.T. (author), van der Veen, A.J. (author)
The estimation of the coordinates of nodes their proximity (or distance) measurements, is a principal challenge in numerous fields. Conventionally, when localizing a static network of immobile nodes, non-linear dimensionality reduction techniques are applied on the measured distances to obtain the relative coordinates up to a rotation and...
journal article 2019
document
Kazaz, T. (author), Rajan, R.T. (author), Janssen, G.J.M. (author), van der Veen, A.J. (author)
Achieving high resolution time-of-arrival (TOA) estimation in multipath propagation scenarios from bandlimited observations of communication signals is challenging because the multipath channel impulse response (CIR) is not bandlimited. Modeling the CIR as a sparse sequence of Diracs, TOA estimation becomes a problem of parametric spectral...
conference paper 2019
document
Kazaz, T. (author), Coutiño Minguez, M.A. (author), Janssen, G.J.M. (author), Leus, G.J.T. (author), van der Veen, A.J. (author)
Synchronization and ranging in internet of things (IoT) networks are challenging due to the narrowband nature of signals used for communication between IoT nodes. Recently, several estimators for range estimation using phase difference of arrival (PDoA) measurements of narrowband signals have been proposed. However, these estimators are based...
conference paper 2019
document
Abdikivanani, B. (author), Hendriks, R.C. (author), van der Veen, A.J. (author), de Groot, N.M.S. (author)
Finding the hidden parameters of the cardiac electrophysiological model would help to gain more insight on the mechanisms underlying atrial fibrillation, and subsequently, facilitate the diagnosis and treatment of the disease in later stages. In this work, we aim to estimate tissue conductivity from recorded electrograms as an indication of...
journal article 2019
document
Naghibzadeh, S. (author), Repetti, Audrey (author), van der Veen, A.J. (author), Wiaux, Yves (author)
Current and future radio telescopes deal with large volumes of data and are expected to generate high resolution gigapixel-size images. The imaging problem in radio interferometry is highly ill-posed and the choice of prior model of the sky is of utmost importance to guarantee a reliable reconstruction. Traditionally, one or more...
conference paper 2018
document
Naghibzadeh, S. (author), van der Veen, A.J. (author)
Image formation in radio astronomy is a large-scale inverse problem that is inherently illposed. We present a general algorithmic framework based on a Bayesian-inspired regularized maximum likelihood formulation of the radio astronomical imaging problem with a focus on diffuse emission recovery from limited noisy correlation data. The...
journal article 2018
document
Mouri Sardarabadi, A. (author), van der Veen, A.J. (author)
Many subspace-based array signal processing algorithms assume that the noise is spatially white. In this case, the noise covariance matrix is a multiple of the identity and the eigenvectors of the data covariance matrix are not affected by it. If the noise covariance is an unknown arbitrary diagonal (e.g., for an uncalibrated array), the...
journal article 2018
document
Mouri Sardarabadi, A. (author), van der Veen, A.J. (author), Koopmans, L.V.E. (author)
For subspace estimation with an unknown colored noise, Factor Analysis (FA) and its extensions, denoted as Extended FA (EFA), are good candidates for replacing the popular eigenvalue decomposition (EVD). Finding the unknowns in (E)FA can be done by solving a non-linear least square problem. For this type of optimization problems, the Gauss...
conference paper 2018
document
Mouri Sardarabadi, A. (author), van der Veen, A.J. (author), Koopmans, Leon V.E. (author)
Having an accurate calibration method is crucial for any scientific research done by a radio telescope. The next generation radio telescopes such as the Square Kilometre Array (SKA) will have a large number of receivers which will produce exabytes of data per day. In this paper we propose new direction-dependent and independent calibration...
conference paper 2018
document
Mouri Sardarabadi, A. (author), Leshem, A. (author), Van der Veen, A.J. (author)
Aims. Image formation for radio astronomy can be defined as estimating the spatial intensity distribution of celestial sources throughout the sky, given an array of antennas. One of the challenges with image formation is that the problem becomes ill-posed as the number of pixels becomes large. The introduction of constraints that incorporate a...
journal article 2016
document
Xie, Y. (author), Janssen, G.J.M. (author), van der Veen, A.J. (author)
A clock synchronization scheme is crucial for obtaining accuracy in time-based positioning systems. Existing clock synchronization schemes are mostly based on a simplified linear clock model, which unfortunately have a poor long-term synchronization accuracy. Assuming a two-way time transfer protocol, we propose a novel clock synchronization...
conference paper 2016
document
Naghibzadeh, S. (author), Mouri Sardarabadi, A. (author), van der Veen, A.J. (author)
Image formation using the data from an array of sensors is a familiar problem in many fields such as radio astronomy, biomedical and geodetic imaging. The problem can be formulated as a least squares (LS) estimation problem and becomes ill-posed at high resolutions, i.e. large number of image pixels. In this paper we propose two regularization...
conference paper 2016
document
Rajan, R.T. (author), Boonstra, A.J. (author), Bentum, M. (author), Klein-Wolt, M. (author), Belien, F. (author), Arts, M. (author), Saks, N. (author), Van der Veen, A.J. (author)
The past decade has seen the advent of various radio astronomy arrays, particularly for low-frequency observations below 100 MHz. These developments have been primarily driven by interesting and fundamental scientific questions, such as studying the dark ages and epoch of re-ionization, by detecting the highly red-shifted 21 cm line emission....
journal article 2015
document
Sarijari, M.A.B. (author), Abdullah, M.S. (author), Janssen, G.J.M. (author), Van der Veen, A.J. (author)
The growing number of wireless devices for in-house use is causing a more intense use of the spectrum to satisfy the required quality-of-service such as throughput. This has contributed to spectrum scarcity and interference problems particularly in home area networks (HAN). Cognitive radio (CR) has been recognized as one of the most important...
journal article 2015
document
Rajan, R.T. (author), Van der Veen, A.J. (author)
Synchronization and localization are critical challenges for the coherent functioning of a wireless network of mobile nodes. In this paper, a novel joint non-linear range and affine time model is presented based on two way time stamp exchanges, extending an existing affine time-range model. For a pair of nodes, a closed form pairwise least...
conference paper 2013
document
Bentum, M.J. (author), Verhoeven, C.J.M. (author), Boonstra, A.J. (author), Van der Veen, A.J. (author), Gill, E.K.A. (author)
OLFAR, Orbiting Low Frequency Antennas for Radio Astronomy, will be a space mission to observe the universe frequencies below 30 MHz, as it was never done before with an orbiting telescope. Because of the ionospheric scintillations below 30 MHz and the opaqueness of the ionosphere below 15 MHz, a space mission is the only opportunity for this as...
conference paper 2009
document
Wang, Y. (author), Leus, G. (author), Van der Veen, A.J. (author)
A complete detection, channel estimation, synchronization, and equalization scheme for a transmitted reference (TR) ultra-wideband (UWB) system is proposed in this paper. The scheme is based on a data model which admits a moderate data rate and takes both the interframe interference (IFI) and the intersymbol interference (ISI) into consideration...
journal article 2009
document
Djapic, R. (author), Leus, G. (author), Van Der Veen, A.J. (author), Trinda, A. (author)
Ultra-wideband (UWB) wireless communication systems are based on the transmission of extremely narrow pulses, with a duration inferior to a nanosecond. The application of transmit reference (TR) to UWB systems allows to side-step channel estimation at the receiver, with a tradeoff of the effective transmission bandwidth, which is reduced by the...
journal article 2006
document
Dang, Q.H. (author), Trindade, A. (author), van der Veen, A.J. (author), Leus, G. (author)
journal article 2006
Searched for: author:"Van der Veen, A.J."
(1 - 20 of 99)

Pages