Ricerc@Sapienza

Passive radar, or Passive Coherent Location (PCL), has reached a stage of maturity for stationary PCL receivers exploiting stationary transmitters of opportunity. The next logical step is to place PCL receivers on moving platforms. Mounting PCL receivers on airborne platforms poses a challenge to the system designer.

The aim of the work is to investigate the performance of two localization techniques based on WiFi signals: the WiFi-based passive radar and a device-based technique that exploits the measurement of angle of arrival (AoA) and time difference of arrival. This paper focuses specifically on the accuracy of the AoA measurements. As expected, the results show that for both techniques the AoA accuracy depends on the signal-to-noise ratio also in terms of the number of exploited received signal samples.

This paper addresses the problem of clutter cancellation and slowly moving target detection in digital video broadcast-terrestrial-based passive radar systems mounted on moving platforms. First, we show that conventional processing approaches based on the availability of multiple receiving channels might be ineffective in the considered scenarios due to the impossibility to control the employed waveform of opportunity.

This paper addresses the problem of direct signal interference (DSI) and clutter cancellation for passive radar systems on moving platforms using displaced phase centre antenna (DPCA) approach in the presence of receive channels imbalance. First, we show that using the signal emitted by the illuminator of opportunity as a source for channels calibration might be ineffective when DSI and clutter echoes have different directions of arrival. Then, a calibration approach is presented, based on supervised selection of clutter areas in the range-Doppler map.

This paper addresses the problem of clutter cancellation for ground moving target indication (GMTI) in multi-channel passive radar on mobile platforms. Specifically, the advantages of a space-time adaptive processing (STAP) approach are presented, compared to a displaced phase centre antenna (DPCA) approach, in the case of an angle-dependent imbalance affecting the receiving channels. The schemes are tested against simulated clutter data.

This paper addresses the problem of direct signal interference (DSI) and clutter cancellation for passive radar systems on moving platforms employing displaced phase centre antenna (DPCA) approach. Attention is focused on the development of signal processing strategies able to compensate for the limitations deriving from amplitude and phase imbalances that affect the two channels employed on receive.

In this paper, we report the latest developments obtained with the FM-based configuration of the AULOS® passive radar system designed by Leonardo SpA for air surveillance applications. Specifically, aiming at improving the target detection capability of the sensor, a robust disturbance cancellation technique is adopted. Moreover, to counteract the time-varying performance of the single FM channel we consider the joint exploitation of multiple FM radio channels.

The last results obtained with the Eco-friendly dual-band AULOS® passive radar sensor carried out within the long-term collaboration between Sapienza University of Rome and Leonardo S.p.A. are here reported. Specifically, FM and DVB-T signals are parasitically exploited for air and maritime surveillance applications. A significant effort concerned the development of signal processing techniques to be efficient in both the investigated applications. To this purpose, the recent processing techniques developed by the research group of Sapienza have been applied.

In this paper we address the problem of target’s range migration in passive bistatic radar exploiting long coherent integration times with fairly wideband signals of opportunity. We resort to the well-known Keystone Transform (KT) to compensate for the range walk effect and to take advantage of a higher coherent integration gain against targets with non-negligible radial velocity.

In this paper, we consider the exploitation of a DVB-T based Passive Radar for simultaneous short and long range surveillance of drones and aircrafts, respectively. In detail, an airport terminal area surveillance application is considered and the effectiveness of the employed sensor is investigated with reference to the two search tasks to be accomplished simultaneously. For the purpose of our analysis, experimental data have been collected by means of the DVB-T based AULOS® passive sensor developed by Leonardo S.p.A against both a very small RCS drone and conventional air traffic.