Currently there is a strong interest in transported radar systems, in which the radar receiver can be mounted either on air or land vehicles. One of the main challenges of these systems is to properly filter the interferences produced by the so-called clutter, which refers to all the reflections given by non-moving scatterers located within the radar coverage.
In this perspective, the aim of the proposed project is to develop filtering techniques for clutter cancellation based on the use of Non-Uniform Linear Arrays (NULAs). These arrays are particularly suited for low-budget radar applications, due to their lightness and their low economic and computational costs.
The interest in transported radar systems is being fostered by industries such as the security and the automotive ones. On the one hand, the recent advancements in the development of unmanned vehicles has completely revolutionised the way of thinking about security systems, which in turn has generated great interest in the use of radar systems that have to deal with moving unmanned vehicles. On the other hand, the automotive industry has defined the concept of automotive radar: a radar that, in addition to classical tasks such as detection and tracking, has to be designed with a view to the avoidance of vehicle collisions.
Within the scope of the project, we also aim at validating the proposed cancellation techniques through experimental campaigns, exploiting a mechanical and electronic testing system that is already 90% developed. The experimental framework developed allows to test the filtering techniques in the case study of a passive radar exploiting DVB-T signals, moving the radar along with the entire acquisition system so as to simulate a vehicle with a previously configured speed pattern. This will allow us to test the proposed cancellation techniques in an extremely realistic environment, giving rise to strong and closed conclusions regarding the use of NULAs in state-of-the-art technologies.
As already mentioned, the main motivation to support this research project is the growing interest in civilian radar applications. In fact, applications such as autonomous driving, health monitoring and drone radiolocation are the new focus of the modern radar industry. The main issue in these cases is to fulfill all challenging use cases with satisfactory performance, while minimizing costs. As a matter of fact, civilian applications usually require low budget systems in which the economical and the computational costs should be reduced as much as possible. In this perspective, it is worth investigating signal processing techniques and design strategies that aim at minimizing them. The proposed project addresses this issue in at least three different ways.
Firstly, phased arrays are particularly suited for cost containment, as they might be realized using Commercial off-the-shelves (COTS) components, hence avoiding the use of ad hoc designed antennas. Furthermore, as previously mentioned, studying clutter cancellation techniques which can reach its maximum potential when applied to Non-Uniform Linear Arrays further moves towards the direction of low-budget systems. As a matter of fact, a performance study on NULAs as well as the identification of a design strategy for optimal non-uniform sensor distributions may allow to obtain performances which are comparable to those of ULA, without employing as many sensors. Hence, this might be particularly useful not only in keeping economic and computational costs under control, but also in reducing the size and the weight of the radar receiver, which may help to fulfill requirements typical of airborne or spaceborne applications.
Secondly, the proposed research aims at suggesting alternative clutter cancellation techniques, which could supplement the already existing ones. In this perspective, improving the performances of deterministic cancellation filters such as DPCA, allows to obtain satisfactory performances without necessarily resorting to adaptive techniques like STAP, which are computationally heavier.
Thirdly, both the simulations and the planned experimental campaigns are intended to address the case of a passive radar exploiting DVB-T frequencies. The great advantage of passive radar is that they do not need to transmit any signal, and hence they are able to preserve radar¿s functionalities without further occupying the already crowded electromagnetic spectrum. This is why passive radars are particularly suited for low-budget applications.