Abstract:To improve the detection accuracy of shortwave signals in complex electromagnetic environments and address the issues of weak signal features, severe background noise interference, and significant signal scale variations that lead to insufficient detection precision, a shortwave signal detection algorithm based on YOLOv11n was investigated. An improved shortwave signal detection algorithm, named AFM-YOLO, was proposed. The algorithm deeply integrates the AssemFormer module with C3K2 in the backbone network to construct the C3K2_AssemFormer module, combining the local feature extraction capability of convolutions with the global context modeling advantage of Transformers to enhance feature preservation for weak signals. A frequency-domain-based self-attention solver (FSAS) module was introduced, leveraging the efficiency of frequency-domain computation to reduce the complexity of the attention mechanism and improve the model's feature discrimination capability in noisy environments. A multi-branch auxiliary feature pyramid network (MAFPN) structure was designed in the neck network, employing a bidirectional fusion mechanism to strengthen the interaction between shallow-layer detail information and deep-layer semantic information, thereby improving the detection capability for multi-scale signals. Experimental validation was conducted on a self-built dataset containing ten types of shortwave signals, including ANDVT, 2GALE, and LINK11. The results indicate that AFM-YOLO achieves mAP50 and mAP50-95 scores of 93.5% and 88.3%, respectively, representing improvements of 3.7 and 10.6 percentage points over the baseline YOLOv11n model. The precision rate increased by 3.5 percentage points to 94.5%, and the recall rate increased by 5.9 percentage points to 91.2%. The proposed algorithm can effectively enhance the detection accuracy of shortwave signals in complex electromagnetic environments.