Jie Bin

Frequency-hopping (FH) communication is widely employed in modern wireless communication systems due to its strong resistance to interference. Accurate detection of FH signals is therefore essential for effective spectrum monitoring and reliable communication in complex electromagnetic environments. However, real-world electromagnetic environments are highly complex and dynamic, with substantial noise and multiple interfering signals coexisting. These conditions pose significant challenges to frequency-hopping signal detection, particularly in terms of low signal-to-noise ratios and co-channel interference. To address these challenges, this paper proposes a frequency-hopping signal detection method based on time–frequency cancellation and the Hough transform. The received signals are first preprocessed using time–frequency cancellation and singular value decomposition to suppress noise and fixed-frequency interference. Subsequently, the time–frequency characteristics of the preprocessed signals are extracted, and the time–frequency cancellation ratio is computed to perform an initial determination of the presence of frequency-hopping signals. To further reduce false detections caused by multiple interference sources, the Hough transform is applied to analyze the time–frequency spectrum in greater detail. By jointly exploiting the geometric and statistical characteristics of the signals, accurate detection of frequency-hopping signals is achieved. Experimental results demonstrate that the proposed method enables precise detection of frequency-hopping signals under challenging electromagnetic conditions.

In low-resource speech recognition, the performance of the Whisper model is often limited by the size of the available training data. To address this challenge, this paper proposes a training optimization method for the Whisper model that integrates Low-Rank Adaptation (LoRA) with the Optuna hyperparameter optimization framework. This combined approach enables efficient fine-tuning and enhances model performance. A dual-metric early stopping strategy, based on validation loss and relative word error rate improvement, is introduced to ensure robust convergence during training. Experimental data were collected from three low-resource languages in Xinjiang, China: Uyghur, Kazakh, and Kyrgyz. Compared to baseline LoRA fine-tuning, the proposed optimization method reduces WER by 20.98%, 6.46%, and 8.72%, respectively, across the three languages. The dual-metric early stopping strategy effectively shortens optimization time while preventing overfitting. Overall, these results demonstrate that the proposed method significantly reduces both WER and computational costs, making it highly effective for low-resource speech recognition tasks.