Ricerc@Sapienza

This paper investigates the target detection capability of a Passive Forward Scatter Radar (PFSR) exploiting a DVB-T transmitter as illuminator of opportunity. Specifically, it is shown that conventional processing schemes adopted in PFSR might suffer from significant performance degradation when dealing with OFDM waveforms of opportunity compared to the case of FM radio broadcast. In fact, a non-negligible increase of the disturbance background is observed in the final spectrogram, which yields an undesired masking effect on weak target echoes.

Research in passive radar has moved its focus towards passive radar on moving platforms in recent years with the purpose of moving target indication and ground imaging via synthetic aperture radar. This is also fostered by the progress in hardware miniaturization, which alleviates the installation of the required hardware on moving platforms. Terrestrial transmitters, commonly known as illuminators of opportunity in the passive radar community, usually emit the signals in the Very High Frequency (VHF) or Ultra High Frequency (UHF) band.

Polarimetric diversity has been recently shown to significantly improve the target detection performance in passive radar systems, if properly exploited to mitigate the competing interference. An adaptive processing scheme is presented in this work, leveraging the information conveyed using multi-polarized receiving antennas and modeling the disturbance as a multichannel autoregressive process.

In this paper we investigate the two-dimensional target localization and motion parameters estimation capabilities of a near Forward Scatter (NFS) Radar system with a dual receiving antenna. Taking advantage of the low-cost Crystal Video Detector (CVD) commonly adopted in Forward Scatter Radar (FSR) configurations, in this work we propose a short-time CVD to test for target detection.

This paper presents results of an experimental trial aimed at detecting a car and a flying drone, passively, by exploiting transmissions of opportunity from a staring Holographic radar. Results show that targets could be successfully detected using a low-cost passive receiver prototype. This may be considered a first step towards a radar network that could provide more comprehensive coverage, over a wider area, against a broader set of target types and without requiring additional spectral resources.

The focus of this work is on the estimation of the motion parameters of moving targets by means of a dual receive antenna Forward Scatter Radar (FSR) configuration. For this purpose (i) the Doppler signature spectrogram for the single node FSR configuration and (ii) the time delay technique based on the cross-correlation between the signals acquired by a FSR system comprising two different receivers, are both analysed for the joint estimation of the baseline crossing point and of the cross baseline velocity.

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.

The exploitation of the Global Navigation Satellite Systems (GNSS) as transmitters of opportunity in passive radar systems for maritime surveillance is particularly attractive because of the main advantages consisting in a global coverage (even in open sea) and in the availability of multiple sources (different satellites and constellations). The main drawback stays in the restricted power budget provided by navigation satellites. This characteristic makes necessary to conceive, define and develop detection techniques able to overcome such limitation.

The possibility of obtaining cross-range profiles of aerial targets is contemplated in this paper by applying inverse synthetic aperture radar (ISAR) techniques against FM-based passive radar data. The considered application is shown to pose a number of limitations, mostly related to the very long coherent processing interval required to attain a reasonable cross-range resolution. To mitigate such limitations, a suitable two-stage ISAR processing scheme is proposed for the estimation of the target motion induced phase history and its compensation.

This paper investigates the feasibility of using the Global Navigation Satellite Systems (GNSS) as transmitters of opportunity in a passive bistatic radar system for maritime target detection applications. To this purpose, the experimental test bed was developed, and the practical campaign was conducted for maritime data acquisition with the new Galileo satellites and a ferry as the target.