Wim van Rossum

Compressive CFAR radar detection

In this paper we develop the first Compressive Sensing (CS) adaptive radar detector. We propose three novel architectures and demonstrate how a classical Constant False Alarm Rate (CFAR) detector can be combined with l1-norm minimization. Using asymptotic arguments and the Complex Approximate Message Passing (CAMP) algorithm we characterize the statistics of the l1-norm reconstruction error and derive closed form expressions for both the detection and false alarm probabilities. We support our theoretical findings with a range of experiments that show that our theoretical conclusions hold even in non-asymptotic setting. We also report on the results from a radar measurement campaign, where we designed ad hoc transmitted waveforms to obtain a set of CS frequency measurements. We compare the performance of our new detection schemes using Receiver Operating Characteristic (ROC) curves.

Array aperture extrapolation using sparse reconstruction

In this paper we present some preliminary results on antenna array extrapolation for Direction Of Arrival (DOA) estimation using Sparse Reconstruction (SR). The objective of this study is to establish wether it is possible to achieve with an array of a given physical length the performance (in terms of accuracy, resolution and sidelobe level) of an equivalent larger array by using SR. The difference between our work and previous publications on DOA estimation using SR lies in the fact that we do not use SR as a beamformer, but instead we use the sparse solution for aperture extrapolation. We adopt an approach similar to the one of Swingler and Walker in [1], where the extrapolated sensor data are first tapered and then beamformed to suppress sidelobes of strong interfering targets, resulting in improved detection of weak targets.

Array calibration technique for a coherent MIMO radar

In this paper we present a technique to estimate the calibration coefficients of a coherent Multiple-Input Multiple-Output (MIMO) array radar built on a printed circuit board (PCB). Due to the integrated structure and the MIMO nature of the system, a direct measurement of each antenna element behavior cannot be performed. The proposed method is based on the evaluation of the calibration parameters from the signal reflected by dominant targets, located at different range bins, and it does not require the a priori knowledge of their angular positions. Experimental validation of the presented technique has been done and the related results are illustrated.

Random transmission scheme approach for a FMCW TDMA coherent MIMO radar

In this paper the authors analyze the use of Time Division Multiple Access (TDMA) applied to coherent Multiple-Input Multiple-Output (MIMO) radar systems. One of the main limitations in exploiting the orthogonal condition in the time domain for MIMO radars is the reduction of the unambiguous Doppler interval. With respect to frequency modulated continuous waveform (FMCW) systems, the authors present a possible solution which is based on the introduction of a random selection of the active transmitter. The analytical representation of the signal model is described and the simulated results of the proposed approach are shown.

Automatic detection of hostile behaviour

In current military operations threats should be monitored accurately. The use of sensors is indispensable for this purpose, for example with camera and radar systems. Using data from such systems we have studied automated procedures for extracting observable behavioral features of persons and groups, which can be associated with threats. We have analysed algorithms for identifying animals versus humans, and for determining the activity of detected humans. Secondly, geospatial algorithms are studied to determine people in suspicious places.

Near field resolution measurements with the leaky wave antennas

Leaky wave antennas operate in a wide frequency band, have a relatively high gain and high pulse fidelity. These properties are valuable for a GPR system, where often a trade-off between antenna efficiency and operational bandwidth has to be made. This paper presents laboratory measurements of near field resolution with two leaky wave antennas in a quasi-monostatic setup.

Space-Time Block Coding waveform for suppression of jamming in a MIMO radar

In a phased array radar which uses Multiple Input Multiple Output (MIMO) techniques, each (group of) element(s) transmits a different waveform. This extra degree of freedom in the design of a phased array radar potentially yields an advantage for improved suppression of sidelobe clutter and jamming. In this paper a Space-Time Block Coding (STBC) waveform for suppression of jamming in a MIMO radar is investigated and compared to space-coded waveforms such as TDMA and FDMA.

Scalable multifunction RF system concepts for joint operations

RF systems based on modular architectures have the potential of better re-use of technology, decreasing development time, and decreasing life cycle cost. Moreover, modular architectures provide scalability, allowing low cost upgrades and adaptability to different platforms. To achieve maximum benefit from modularity and scalability, the challenge is to define the front-end concept in such a way that it supports multiple functions and is applicable in multiple environments and platforms. This paper describes concepts for such modular systems that may be used for RF functions in maritime, airborne and land based systems. The first part discusses general scalability properties of various RF functions, the second part discusses example system concepts in a ‘joint’ scenario (land/sea/air). The focus of this paper is on X-Ku band systems: considering essential RF functions like radar and communication, and the types of platforms in maritime, land-based and airborne operations, this frequency range provides the highest potential for application in all these domains and platforms. Conceptual designs for weapon location radar, SAR/GMTI, surveillance radar and tactical data link are presented.