Jonathan Bosse

Passive geolocalization of radio transmitters: Algorithm and performance in narrowband context

Passive localization commonly consists of a two steps strategy. In the first step, intermediate parameters, often called measurements (such as angles of arrival (AOA), times of arrival (TOA), etc.) are measured on several base stations equipped with sensor arrays. In a second step, the transmitted intermediate parameters are then used to estimate the position at a central processing unit. Such approach is suboptimal. To overcome this limitation, one step algorithms were recently proposed. They exploit simultaneously all received signals of all base stations seen as a global array in order to provide the source positions directly. In this paper, we propose an original one step algorithm called global MUSIC approach (GMA). The GMA offers better performance in narrowband context. Moreover it does not require the use of filter banks in the wideband signal context, contrary to the recently proposed direct position determination (DPD). GMA appears to outperform the DPD in wideband context. We also investigate in this paper by means of a Cramer-Rao bound analysis the potential gain achievable by a one step approach compared to a conventional two steps approach. Finally, numerical results illustrate the improvement of the proposed method compared to existing techniques in terms of location error and robustness to the time-bandwidth product.

A space time array processing for passive geolocalization of radio transmitters

The problem of passive localization is commonly solved by independently measuring intermediate parameters (such as angles of arrival (AOA), times of arrival (TOA)…) on several multiple sensors base stations in a first step. In a second step, the transmitted parameters are then used to estimate the position. Recently, studies proposed new promising one step algorithms based on stacked multiple station observations vectors gathering all received signals of all base stations. This strategy leads naturally to a wideband estimation problem, solved in this paper by an alternative space-time processing. The proposed algorithm is compared to existing techniques and the corresponding Cramer-rao bound.

Matching pursuit via continuous resolution cell rejection in presence of unresolved radar targets

In this article a new matching pursuit algorithm with continuous radar resolution cell rejection is proposed. It allows matching pursuit to work well even if more than one target is present in some resolution cell (unresolved targets) of the radar matched filter: it prevents its tendency to generate spurious sidelobes or miss a weaker target hidden in stronger target sidelobes. The FMCW radar case is particularly investigated which offers a very natural and computationally inexpensive solution to the problem that can also be applied in spectral analysis. The extension of the proposed approach to any radar waveform is also investigated.

Off-grid target detection with normalized matched subspace filter

The problem of off-grid target detection with the normalized matched filter (NMF) detector is considered. We show that this detector is highly sensitive to off-grid targets. In particular its mean asymptotic detection probability may not converge to 1. We then consider two solutions to solve this off-grid problem. The first solution approximates the Generalized Likelihood Ratio Test (GLRT) by oversampling the resolution cell; this solution may be computationally heavy and does not permit to compute a theoretical detection threshold. We then propose a second solution based on the matched subspace detection framework. For Doppler steering vectors, the subspace considered is deduced from Discrete Prolate Spheroidal Sequence vectors. Simulation results permit to demonstrate interesting performance for off-grid targets.

A glance on geographical positioning

Geographical positioning has attracted considerable interest during the last decades due to the potential of such an information for civilian applications as well as for military applications. This paper recalls the main issues and solutions in some localization problems depending on the experimental context. It offers a brief review and evokes recent directions in which studies are led. This paper is an introduction paper for the special session “Advances in geographical positionning” in CAMSAP 2011. It provides a common framework for the research papers which will be presented in the session.