Development of an Unmanned Aerial System for Radio Frequency Source Localization

Abstract

Radio-based direction finding is an old concept for manned aircraft where a pilot manually flies towards the directed bearing. However, it is a relatively new field of study for unmanned aerial systems like quad-rotors especially motivated by the desire of making the homing process autonomous. In this study, the received signal strength method to localize the radio source has been applied and tested. The proposed method employs a UAS equipped with a radio frequency (RF) receiver to get RSSI readings from the RF source. The obtained RSSI measurements at three receiving locations are converted to approximate distances from the transmitter using a log-distance path loss model, and the localization algorithm based on trilateration is run onboard the microcomputer to localize the radio transmitter. Through simulations and experiments, the performance of the suggested method is assessed. The verification mission employing the suggested technique localized the RF source with a distance error of 15.8 meters and an angle error of 8.62 degrees, at best, whereas the actual UAS-based flight localized it to the distance accuracy of 25 meters, and the angle accuracy of 8.32 degrees at a test domain of 100 meters radius.