Real-time Frequency Offset Estimation and Demodulation Method of DroneID Signal

The DroneID signal transmitted by drones carries important information, including real-time coordinate position and ID serial number of the drone and controller. In recent years, adequate reception and demodulation of these signals have become focal points in unmanned aerial vehicle (UAV) monitor research. The actual DroneID signals exhibit low signal-to-noise ratio (SNR) and substantial frequency offsets, leading conventional demodulation techniques to suffer from low estimation accuracy of frequency offset and operational failure under significant frequency offset. This results in prolonged demodulation delays, high frame loss rates and high bit error rates (BER). This paper analyzes the time-frequency characteristics of DroneID signals, and proposes a novel frequency offset estimation and demodulation approach based on parallel streaming processing. By employing high-processing gain symbol for frequency offset measurement and executing frequency offset calculation and demodulation in parallel, real-time streaming processing is achieved, enhancing the accuracy of frequency offset estimation and the responsiveness of demodulation across frames. Simulation results demonstrate that under conditions of SNR at -14dB and frequency offset of 8kHz, the proposed method achieves frequency offset estimation accuracy of 1kHz, satisfying real-time demodulation needs for low SNR and large frequency offset signals.