Interference of Radar Detection of Drones by Birds

Abstract

Recently, consumer drones have encroached upon airports and pose a potential threat to aviation safety. Radar is an effective remote sensing tool to detect and track flying drones. Radar echoes from flying birds are assumed to be clutters when a radar is detecting drones. Yet, few studies have reported how radar echoes from flying birds interfere with the detection of drones, how similar radar cross section (RCS) and flight feature of birds and drones are, and why the flying birds cause trouble when radar identifies signals from the drone. In this study, we collected 3900 × 256 of Ku-band radar echoes of flying birds and consumer drones. The targets consist of a pigeon, a crane, waterfowl, and a DJI Phantom 3 Vision drone. We compared the maximum detectable range of birds and drones, the time series and the Doppler spectrum of radar echoes from the birds and the drone, considering oncoming and outgoing radar data with respect to radar location. The statistical results indicate that flying birds have similar RCS, same velocity range, similar signal fluctuation, and approximate signal amplitude. Our results of radar automatic target recognition (ATR) illuminate that the identification probability of airborne drones will be lower due to the interference of the radar signal by flying birds. Above all, these facts confirm that flying birds are the main cause of interference when a radar is detecting and identifying airborne drones.

Comparison of radar signatures based on flight morphology for large birds and small birds

“…Not all radar bands can capture those radar signatures. The radar scattering field begins with the relationship between radar wavelength and bird size, and there are three scattering regions to describe the scattering mechanism [26, 27]. If we want to recognise bird feet position in the air and classify radar echoes from a large bird and a small bird, the radar wavelength must be far smaller than the bird size; that means radar data come in the optic scattering region.…”

A Survey of Strategies, and Procedures for Detecting Drone Utilizing Sound, Radar, Thermal Infrared Sensor and Video Applications

“…This is because those systems frequently incorporate a built-in feature that works at reducing undesired echoes from small, slow, and low-flying objects, and as such fail to detect the drones in question. The small Radar Cross Sections (RCS) of medium-sized consumer drones are well described in [11], and the results show that flying birds have similar RCS, which can lead to false detection of such targets when attempting to detect drones.…”

Real-Time Drone Detection and Tracking With Visible, Thermal and Acoustic Sensors

“…However, detecting drones with systems designed for aircrafts is not straightforward because they often use techniques to reduce unwanted echoes from small, slow and low-flying objects, which is precisely what characterise drones. Also, the Radar Cross Sections (RCS) of medium-sized consumer drones are similar to birds, which can lead to false targets [31]- [33]. Nevertheless, several works have explored the use of micro-doppler characteristics of drones [34]- [37].…”