Analytical and mathematical modeling of long-range UAV telemetry systems under electromagnetic

Abstract

Reliable and interference-resilient telemetry links are essential for ensuring stable command and control of Unmanned Aerial Vehicles (UAVs), particularly in environments characterized by electromagnetic congestion or deliberate jamming. Conventional 2.4 GHz FHSS-based systems, such as AFHDS 2A used in FlySky controllers, generally require positive signal-to-noise ratios to maintain link integrity, which significantly limits their operational range and robustness. In contrast, modern telemetry architectures such as ExpressLRS (ELRS), which employ LoRa/FLRC waveforms with substantial processing gain, are capable of sustaining communication even under negative SNR conditions. This fundamental distinction motivates the need for a rigorous comparative evaluation of both technologies under realistic interference scenarios. This study presents a unified analytical and mathematical modeling framework for assessing the performance of long-range UAV telemetry systems subjected to electromagnetic and jamming interference. Two UAV platforms were constructed for this purpose: one using an ELRS-based telemetry module and the other equipped with a traditional FHSS-based FlySky FS-i6 system. The analysis incorporates three-dimensional UAV propagation modeling, altitude-dependent path-loss characterization, processing-gain-enhanced SNR estimation, jamming-aware SINR behavior, and modulation-specific BER/PER formulations. A new metric—Robustness Index (RI)—is introduced to provide a quantitative comparison of link resilience across architectures.
Analytical results reveal that ELRS offers up to an order-of-magnitude improvement in link budget, extended operational range, and stronger resilience to interference, enabling reliable telemetry at distances approaching 10 km. Conversely, FHSS-based systems demonstrate performance degradation and link collapse beyond approximately 1–1.5 km. The findings offer a methodological foundation for designing UAV telemetry systems capable of reliable operation in contested electromagnetic environments.