Direction of arrival estimation using a cluster of beams in a cone-shaped digital array radar'

In this paper some potential system and processing advantages of conformal cone shaped digital array radar have been investigated, in particular in relation to potential alternative approaches for angle estimation with respect to the traditional monopulse. First of all potential benefit in terms of reduction of the number of radiating elements is shown when a conical array is considered with respect to a traditional system formed by four planar arrays, if a coverage of 360° must be assured. Secondly, having in mind an innovative digital array system where the received signals are analog to digital converted at element level and the corresponding data are possibly transferred to a central elaboration unit, an alternative approach is investigated for angular estimation. In this paper we derive the theoretical expression of the Cramer Rao Lower Bound for elevation angle estimation using a cluster of beams; we compare the limit performance of the traditional approach for angle estimation based on Sum and Difference beams with the approach based on a crowded cluster of RX beams properly spaced. The approaches show approximately equivalent performance, making the second particularly interesting for those situations where monopulse is known to experience performance degradation, as low elevation angle estimation; in this particular case an example of cluster design is shown, where the direct signal from a low altitude target must compete with a specular multipath

Passive multifrequency forward-scatter radar measurements of airborne targets using broadcasting signals

This paper demonstrates the feasibility and effectiveness of forward-scatter radar (FSR) target detection based on the signals of opportunity made available by standard radio and TV broadcast transmission stations. This passive FSR (P-FSR) operation is obtained by means of a simple and robust correlation process based on self-mixing. This is shown to be very effective in extracting the characteristic FSR modulation produced by airborne targets, from the signals received from frequency modulated, digital audio broadcasting, and digital video broadcasting transmitters of opportunity. Target detectability is discussed as a function of the carrier frequency, the target size, and its height at the baseline crossing. Experimental results are shown using a wide variety of sources of opportunity, target types, baselines, and receiver configurations. The target signatures obtained from the different illuminators are compared and ways of extracting the kinematic parameters of the aircraft are discussed. This validates the claimed effectiveness and robustness of the P-FSR with the presented processing scheme

Sidelobe control for a MIMO radar virtual array

In this paper we address the control of the sidelobe level of the virtual array obtained by a coherent MISO (Multiple Input Single Output) or MIMO (Multiple Input Multiple Output) radar. This is useful for many practical radar systems that could exploit the wide virtual apertures provided by coherent MIMO array, but have a low sidelobe requirement. The solution is obtained by jointly selecting the taper function for the receiving array and the transmitter (TX) displacements to provide a final antenna pattern with the desired properties. Moreover we investigate how beamwidth and SNR change by varying the number of used TXs and the number of isotropic elements used for each TX. © 2013 IEEE

Antenna Sidelobes Level Control in Transmit Subaperturing MIMO Radar

This paper addresses the problem to design a transmitsubaperture multiple-input multiple-output (MIMO) radar showing beam clusters with controlled sidelobe level both for the Tx–Rx pattern experienced from target and clutter and for the Rx-only pattern experienced by external interferences. A design strategy is proposed that provides a MIMO scheme with the desired characteristics, together with a low computational cost and a sensibly narrower main beam than the corresponding single-input-multiple-output scheme. An analysis of the accuracy achievable by the proposed scheme is presented by means of Cram´er–Rao lower bound and Monte Carlo simulations. Moreover, an example application is shown using nonideal waveforms to show the practical effectiveness of this TS-MIMO scheme

Metformin prevented dopaminergic neurotoxicity induced by 3,4-Methylenedioxymethamphetamine administration

Metformin, a well-known antidiabetic drug, has recently been proposed to promote neurogenesis and to have a neuroprotective effect on the neurodegenerative processes induced by the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in models of Parkinson’s disease. Interestingly, metformin has antioxidant properties and is involved in regulating the production of cytokines released during the neuroinflammatory process. Several studies have reported that 3,4-methylenedioxymethamphetamine (MDMA), a recreational drug mostly consumed by young adults, produces a persistent loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) and caudate putamen (CPu) of mice. The aim of this study was to investigate the potential neuroprotective effect of metformin against short- and long-term neurotoxicity induced by MDMA and its role on MDMA-induced hyperthermia. Adult mice received metformin (2 × 200 mg/kg, 11-h intervals, administered orally), MDMA (4 × 20 mg/kg, 2-h interval, administered intraperitoneally), or MDMA plus metformin (2 × 200 mg/kg, 1 h before the first MDMA administration and 4 h after the last). On the second and third day, mice were treated with vehicle or metformin (1 × 200 mg/kg) and sacrificed 48 h and 7 days after the last MDMA administration. The neuroprotective effect of metformin on MDMA-induced dopaminergic damage was evaluated by dopamine transporter (DAT) and tyrosine hydroxylase (TH) immunohistochemistry in SNc and CPu. Metformin prevented the MDMA-induced loss of TH-positive neurons in the SNc and TH- and DAT-positive fibers in CPu, both at 48 h and 7 days after the last MDMA administration. These results show that metformin is neuroprotective against the short- and long-lasting dopaminergic neurodegeneration induced by MDM

Target motion estimation via multi-node forward scatter radar system

The focus of this study is on the estimation of the kinematic parameters of a moving target via a multiple-input-multiple output (MIMO) forward scatter radar (FSR) system. For this purpose, a crossing time-based estimation technique is proposed that exploits the information on the time instants at which the target crosses the individual baselines of multiple FSR nodes to retrieve the target motion parameters. First the accuracy of such technique is investigated from a theoretical point of view through Monte Carlo simulations and then the effectiveness of the proposed approach is demonstrated by applying it to measured MIMO FSR data. Shown results prove the practical applicability of the proposed technique and demonstrate the potential of MIMO FSR configuration