1,721,129 research outputs found
Rivelazione e localizzazione di bersagli con radar multicanale da piattaforma in movimento
No full textSpectral slope-based approach for mitigating bistatic space-time adaptive processing clutter dispersion
No full textIn this study, the effects of bistatic clutter spectral dispersion on space-time adaptive processing (STAP) techniques are considered. A robust spectral slope-based approach is presented for mitigating the bistatic geometry-induced performance loss by pre-processing the secondary data used for covariance estimation. Owing to its capability to compensate both the clutter spectral centres misalignment and the trace slope variability over range, this approach is shown to yield further dispersion reduction with respect to previously proposed strategies, thus improving the performance of STAP. An adaptive version of the proposed approach is also introduced, which is able to extract the required parameters from the same data set used for the covariance matrix estimation, without requiring prior knowledge or ancillary data. The performance analysis against synthetic clutter data shows that the proposed slope-based compensation technique is rather robust with respect to the spectral trace shape and estimation errors, providing equal or better performance with respect to previously derived techniques, depending on the specific bistatic geometry
An alternating transmit approach for STAP with short antenna arrays
No full textThe approach of alternating the transmission between a leading and a trailing antenna sub-aperture from pulse to pulse (ALTX) is presented for radar systems equipped with digital beam forming. ALTX is shown to improve detection and DOA estimation performance with respect to standard transmission with the whole antenna aperture for systems with a short antenna array and a limited number of receiving channels
Polarimetric passive coherent location
No full textIn this paper the exploitation of different linear polarimetric channels is considered as a way to mitigate the effect of interfering sources and to improve the target detection capability in a FM radio-based passive radar. The signals emitted on same/adjacent frequency channels by potential transmitters (other than the illuminator of opportunity) located in the surveillance area are shown to significantly affect the performance of the considered system in terms of both disturbance cancellation and target detection. Moreover, it is verified that the achievable performance is dependent on the adopted polarization at both the reference and surveillance channel since employing vertically or horizontally polarized antennas might yield very different results. Therefore effective approaches are introduced to jointly exploit the diversity of information conveyed by different polarizations at both the reference and surveillance channels. The results are shown against a real data set collected by an experimental multi-channel passive radar prototype developed and fielded at the DIET Dept. of the University of Rome “La Sapienza” (Italy). A significant performance improvement is achieved with the proposed processing schemes that always provide better results than the standard processing of the signals collected at the best polarimetric reference and surveillance channels. Besides the expected improvement due to non-coherent integration of target echoes received on multiple channels, the proposed multi-polarimetric operation is shown to yield a remarkable improvement when operating in a severe interference scenario so that it can be regarded as practical solution for robust and effective PCL
Non-linear STAP filters based on adaptive 2D-FIR filters
No full textThis paper presents a non-linear adaptive approach to the cancellation of clutter echoes in modern AEW radar systems equipped with digital beamforming. Two new STAP schemes are conceived by using different non linear functions that are applied to the output of a bank of adaptive 2D FIR filters. The STAP schemes are shown to yield better detection performance than previously known schemes when operating in a non stationary clutter background containing interfering targets. Since they require a limited increase of the computational load, compared to the single 2D-FIR filters, the proposed schemes can be regarded as practical solutions for robust and effective STAP of radar data
A dual adaptive channel STAP scheme for target detection and DOA estimation
No full textThis paper presents a dual cancelled channel approach to the target detection and estimation with a digital beamforming radar. The proposed STAP (Space-Time Adaptive Processing) scheme is shown to yield comparable detection performance to previously known schemes and higher accuracy in the estimation of the target direction of arrival. Moreover, it has a lower computational cost, since it does not require the numerical maximization of a functional
Potenzialità delle antenne multicanale con elaborazione adattiva per radar da piattaforma spaziale del tipo di COSMO-SkyMed
No full textNon-coherent adaptive detection in passive radar exploiting polarimetric and frequency diversity
No full textThe joint exploitation of polarimetric and frequency diversity is considered in this study as a way to improve the target detection capability in a FM radio-based passive radar. The authors resort to a generalised likelihood ratio test approach and derive a fully adaptive multi-frequency polarimetric detector that optimally combines the signals simultaneously transmitted by a given illuminator of opportunity and received at different carrier frequencies by differently polarised surveillance antennas. The application of the proposed detection scheme to recorded live data demonstrates the effectiveness of the multi-frequency polarimetric operation in typical scenarios, besides the expected improvement due to non-coherent integration of target echoes received on multiple channels. In particular, it is shown to provide remarkable target discrimination capability against interfering sources as well as increased robustness with respect to the time-varying characteristics of the exploited signals of opportunity
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