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Sökning: swepub > (1990-1994) > Ottersten Björn

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1.
  • Wahlberg, Bo, et al. (författare)
  • Robust Signal Parameter Estimation in the Presence of Array Perturbations
  • 1991
  • Ingår i: Proc. of 1991 International Conference on Acoustics, Speech, and Signal Processing, 1991. ICASSP-91.. - Linköping : IEEE. ; , s. 3277-3280
  • Konferensbidrag (refereegranskat)abstract
    • Signal parameter estimators which are less sensitive to perturbations in the array manifold are presented. A parametrized stochastic model for the array uncertainties is introduced. The unknown array parameters can include the individual gain and phase responses of the sensors as well as their positions. Based on this model, a maximum a posteriori (MAP) estimator is formulated. This results in a fairly complex optimization problem which is computationally expensive. The MAP estimator is simplified by exploiting properties of the weighted subspace fitting method. An approximate method that further reduces the complexity is also presented, assuming smallarray perturbations. A compact expression for the MAP Cramer-Rao bound (CRB) on the signal and arrayparameter estimates is derived. A simulation study indicates that the proposed robust estimation procedures achieve the MAP-CRB even for moderate sample sizes.
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2.
  • Ottersten, Björn, 1961-, et al. (författare)
  • Asymptotic Robustness of Sensor Arrary Processing Methods
  • 1990
  • Ingår i: Proceedings of the 1990 International Conference on Acoustics, Speech and Signal Processing. - Linköping : IEEE Signal Processing Society. ; , s. 2635-2638
  • Konferensbidrag (refereegranskat)abstract
    • Methods for estimating the parameters of narrowband signals arriving at an array of sensors are analyzed. Asymptotic results for several estimators have recently appeared in the literature. With few exceptions, the previous analysis requires the incident signal waveforms to be Gaussian random variables. These results are shown to be valid under much more general conditions, i.e. the actual distribution of the signal waveforms does not affect the asymptotic properties of the parameter.
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3.
  • Ottersten, Björn, 1961-, et al. (författare)
  • Robust Source Localization Based on Local Array Response Modeling
  • 1992
  • Ingår i: Proceedings of the 1992 IEEE International Conference on Acoustics, Speech and Signal Processing. - Linköping : IEEE. - 0780305329 ; , s. 441-444 vol.2
  • Konferensbidrag (refereegranskat)abstract
    • Many practical applications of signal processing require accurate determination of signal parameters from sensor array measurements. Most estimation techniques are sensitive to errors in the array response model. Thus, reliable array calibration schemes are of great importance. A paradigm for generating an array model from noise corrupted calibration vectors is developed. The key idea is to use a local parametric model of the sensor responses. The potential improvement using the suggested scheme is demonstrated on real data collected from a full-scale hydroacoustic array.
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4.
  • Viberg, Mats, et al. (författare)
  • A statistical perspective on state-space modeling using subspace methods
  • 1991
  • Ingår i: Proceedings of the 30th IEEE Conference on Decision and Control. - Linköping : Linköping University. - 0780304500 ; , s. 1337-1342
  • Konferensbidrag (refereegranskat)abstract
    • The authors investigate aspects of subspace-based state-space identification techniques from a statistical perspective. They concentrate their efforts on a simple approach which is based on finding the range-space of the observability matrix of a state-space representation. The system description is then found using the shift-invariance property of the observability matrix. It is shown that this results in a consistent system description for multivariable output-error models if the measurement noise is white in time and independent from output to output. The asymptotic covariance of the estimated poles of the system is also derived. In the test case studied, the subspace technique performs comparably with the statistically efficient PE (prediction error) method, whereas the IV (instrumental variable) method does notably worse. Hence, the subspace technique may be a strong candidate for determining initial values for the optimization in the efficient PE method.
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6.
  • Ottersten, Björn, et al. (författare)
  • Analysis of Algorithms for Sensor Arrays with Invariance Structure
  • 1990
  • Ingår i: Proceedings of the 1990 International Conference on Acoustics, Speech and Signal Processing. - Linköping : Linköping University. ; , s. 2959-2962
  • Konferensbidrag (refereegranskat)abstract
    • The problem of estimating signal parameters from sensor array data is addressed. If the array is composed of two identical subarrays, (i.e. one invariance) the ESPRIT algorithm is known to yield parameter estimates in a very cost efficient manner. Recently, the total least squares (TLS) version of ESPRIT has been formulated in a subspace fitting framework. In this formulation, the ESPRIT concept is easily generalized to arrays exhibiting more than one invariance. The asymptotic properties for this class of algorithms are derived. The estimates are shown to be statistically efficient under certain assumptions. The case of a uniform linear array is studied in more detail, and a generalization of the ESPRIT algorithm is proposed by introducing row weighting of the subspace estimate.
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7.
  • Ottersten, Björn, 1961-, et al. (författare)
  • Analysis of Subspace Fitting and ML Techniques for Parameter Estimation from Sensor Array Data
  • 1992
  • Ingår i: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1053-587X .- 1941-0476. ; 40:3, s. 590-600
  • Tidskriftsartikel (refereegranskat)abstract
    • It is shown that the multidimensional signal subspace method, termed weighted subspace fitting (WSF), is asymptotically efficient. This results in a novel, compact matrix expression for the Cramer-Rao bound (CRB) on the estimation error variance. The asymptotic analysis of the maximum likelihood (ML) and WSF methods is extended to deterministic emitter signals. The asymptotic properties of the estimates for this case are shown to be identical to the Gaussian emitter signal case, i.e. independent of the actual signal waveforms. Conclusions concerning the modeling aspect of the sensor array problem are drawn.
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8.
  • Ottersten, Björn, 1961-, et al. (författare)
  • Direction-of-Arrival Estimation for Wideband Signals using the ESPRIT Algorithm
  • 1990
  • Ingår i: IEEE Transactions on Acoustics, Speech and Signal Processing. - : IEEE Signal Processing Society. - 0096-3518. ; 38:2, s. 317-327
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel direction-of-arrival estimation algorithm is proposed that applies to wideband emitter signals. A sensor array with a translation invariance structure is assumed, and an extension of the ESPRIT algorithm for narrowband emitter signals is obtained. The emitter signals are modeled as the stationary output of a finite-dimensional linear system driven by white noise. The array response to a unit impulse from a given direction is represented as the impulse response of a linear system. The measured data from the sensor array can then be seen as the output of a multidimensional linear system driven by white noise sources and corrupted by additive noise. The emitter signals and the array output are characterized by the modes of the linear system. The ESPRIT algorithm is applied at the poles of the system, the power of the signals sharing the pole is captured, and the effect of noise is reduced. The algorithm requires no knowledge, storage, or search of the array manifold, as opposed to wideband extensions of the MUSIC algorithm. This results in a computationally efficient algorithm that is insensitive to array perturbations. Simulations are presented comparing the wideband and ESPRIT algorithm to the modal signal subspace method and the coherent signal subspace method.
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9.
  • Ottersten, Björn, et al. (författare)
  • Local Modeling and Robust Estimation for High-Resolution Direction Finding
  • 1991
  • Ingår i: Proceedings of the 25th Asilomar Conference on Signals Systems and Computers. - Linköping : Linköping University. - 0818624701 ; , s. 1005-1009 vol.2
  • Konferensbidrag (refereegranskat)abstract
    • Many signal processing applications are concerned with estimating signal parameters with high accuracy from sensor array measurements. To obtain accurate location estimates, knowledge of the array response is required. Most estimation techniques are sensitive to perturbations in the array model and array calibration is often necessary. The authors discuss the issue of generating the array response parameterization from a finite number of noise-contaminated calibration vectors. An estimation technique based on local parametric modeling of the array response is proposed. The potential improvement using the suggested scheme rather than an ideal array model is demonstrated on real data collected from a full-scale hydroacoustic array. It is shown that, by applying the proposed technique together with a standard direction-of-arrival estimation procedure, a significant reduction in estimation bias can be obtained.
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10.
  • Ottersten, Björn, 1961-, et al. (författare)
  • Performance Analysis of the Total Least Squares ESPRIT Algorithm
  • 1991
  • Ingår i: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1053-587X .- 1941-0476. ; 39:5, s. 1122-1135
  • Tidskriftsartikel (refereegranskat)abstract
    • The asymptotic distribution of the estimation error for the total least squares (TLS) version of ESPRIT is derived. The application to a uniform linear array is treated in some detail, and a generalization of ESPRIT to include row weighting is discussed. The Cramer-Rao bound (CRB) for the ESPRIT problem formulation is derived and found to coincide with the asymptotic variance of the TLS ESPRIT estimates through numerical examples. A comparison of this method to least squares ESPRIT, MUSIC, and Root-MUSIC as well as to the CRB for a calibrated array is also presented. TLS ESPRIT is found to be competitive with the other methods, and the performance is close to the calibrated CRB for many cases of practical interest. For highly correlated signals, however, the performance deviates significantly from the calibrated CRB. Simulations are included to illustrate the applicability of the theoretical results to a finite number of data.
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  • Resultat 1-10 av 57

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