Multiband passive radar for drones detection and localization

For many surveillance systems, a multisensory architecture is essential when aimingat providing accurate and reliable surveillance of critical infrastructures andprotected areas. This is certainly the case for airports, harbours, prisons and chemicalfacilities as well as for public places such as parking areas, train stations orstadiums, especially due to the new and emerging threat represented by commercialdrones and unmanned aerial vehicles (UAVs). In particular, their small size,low radar reflectivity and flexibility of manoeuvre make them especially difficult todetect, localize and classify. The potentials of passive radar (PR) in counter droneoperations, by exploiting different illuminators of opportunity (IOs), such as DVB-T,DAB, GSM, WiFi, GNSS (Global Navigation Satellite Systems) and DVB-S thatwere introduced in previous chapters, have been recently investigated in severalworks. The reported results demonstrate that such sensors could be effectivelyemployed for detecting and localizing small and medium drones up to a fewkilometres from the PR receiver when DVB-T transmissions are exploited.However, in urban areas and highly populated environments, where the use of thenon-invasive and green PR technology represents an attractive solution for enhancingthe security level, it is important to consider the possibility to exploit amultisensory system by integrating PR with multiple operational frequency bands.The integration of PRs operating at different frequency bands can be obtainedusing two approaches:1. A hardware integration can be conceived that provides a single multibandsensor, which exploits a common multichannel receiver, common datamemory and common processing techniques for different signals of opportunityand therefore greater frequency bandwidth.2. At functional level, where each sensor operates with independent receivingstructures but the outputs of the multiple sensors are combined to provideimproved performance.In the following sections, we proceed as follows. First, in Section 7.2, webriefly review the most attractive sources of opportunity for an anti-drone PRwith their characteristics and signal processing requirements. Three specificsources of opportunity are identified that appear to be well suited for a multibandoperation due to the complementarity of their characteristics. Therefore, weillustrate the concept of the multisensory system on the basis of the parasiticexploitation of such signals and discuss possible implementations and benefits.The different components of the multisensory system are then separatelyaddressed in Sections 7.3–7.5 which are devoted respectively to anti-drone PRbased on DVB-S satellite broadcast signals, DVB-T terrestrial TV and WiFi, inorder to analyse the specific characteristics of their sensors as well as their performance.This analysis also allows to identify hardware and signal processingrequirements for an effective implementation of the integrated multiband PRsystem.