Protection and Safety of Small UAS in Complex Electromagnetic Environments: Modeling and Experiments

Abstract

The survivability of small Unmanned Aerial Systems (sUAS) in high-intensity radio frequency (HIRF) environments is a significant characterization that determines the operability in critical environments. The existing sUAS system designs do not consider the complexity of adversary electromagnetic environments, such as Radio Frequency (RF) interference, electromagnetic interference (EMI), Counter-UAS (C-UAS) electromagnetic attack (EA), and other potential sources of noises in the radio frequency spectrum. This study aims to identify practical approaches for improving the resilience of existing small UAS against HIRF. These improvements are to be evaluated through both controlled laboratory experiments and in situ flight testing. The initial investigation of this study focuses on identifying the weak spots of the existing flight vehicles, from the propeller, motors, and controllers, as well as the internal electronics, especially the RF communication systems and power supplies. The second step emulates the HIRF environment expected in multiple domains (such as air, sea, or ground airport) in laboratory environments. A lab-based emulation test bed is introduced with higher power and better configurations than the previous work [2,3] and installed for the new emulation experiments. The third step performs careful power level calibrations and measures the effects of laboratory-produced HIRF environment on the commercial radios acquired for testing. These results are then compared to the theoretical models. The system setup and size focus on the S-band (2.4 GHz ISM band) radio links, electronic components, onboard GPS, and navigational sensors. This approach is frequency agnostic and can be applied to any radio frequencydevice. From this study, three levels of mitigation are introduced. (1) Minimal protection. (2) Shielding solution. (3) Shielding and EMI filtering solution. Laboratoryand in-situ testing provide evidence of the effectiveness of these mitigation methods in promoting the survivability and operability of sUAVs in HIRF environments near high-power radars. Meanwhile, laboratory testing generates a vendor-independent radio behavior model that may be used for prediction and comparison of radio performance in RFI/EMI/HIRF conditions