关键词: 无人机数据链, 带外电磁干扰, 3阶互调, 干扰效应

Abstract: To address the military demand for the prediction of the effect of complex electromagnetic environment of unmanned aerial vehicle (UAV) data links, a prediction model of third-order intermodulation (IM3) effects from out-of-band electromagnetic interference (EMI) in UAV data links is proposed. The model focuses on direct sequence spread spectrum (DSSS)-based UAV data links and introduces the IM3 effect factor and effect index of the out-of-band EMI based on the analysis of the IM3 effect mechanism. A measurement method for the effect factor is established by integrating theoretical derivations and effect experiments, and IM3 effect experiments of dual-source out-of-band interference injection are used to obtain the effect factor at out-of-band frequencies. To validate the model, effect index experiments of dual-source and three-source out-of-band interference injection are performed. The results show that the peak effect factor at positive frequency offsets reaches 142.89, while that at negative offsets is significantly lower at 54.52, demonstrating stronger resistance to IM3 interference on the negative frequency offset side. Furthermore, the deviation between experimental and theoretical values of the effect index is less than 1.41 dB, validating the accuracy of the proposed model and providing theoretical support for optimizing anti-interference strategies.

Key words: unmanned aerial vehicle data link, out-of-band electromagnetic interference, third-order intermodulation, interference effect