高精度测频与舰船线谱频率稳定性研究

Research on High Accuracy Frequency Estimating and the Frequency Stability of Line Spectrums Radiated by Ships

随着水声技术的发展,水下甚低频信号分析越来越受到研究者的重视。甚低频线谱的稳定性分析对于线谱检测具有重要意义。低信噪比下,传统的自适应频率估计方法性能不理想,为了提高对线谱的检测能力和频率估计的精度,提出一种高精度频率估计器,利用相干累加自适应线谱增强器的方法从宽带噪声中提取单频线谱,进而用自适应频率估计器估计线谱频率。仿真研究证明该估计器在低信噪比时具有较高的频率估计精度。实验研究某舰船声辐射线谱的频率的稳定性,其频率不稳定性约在±0.01 Hz左右。

As the progress of underwater acoustic technology, very low frequency signal analysis attracts more and more interests. The stability analysis of very low frequency is quite important to line spectrum detection. Traditional adaptive frequency estimator cannot reach the qualification under low signal to noise ratio circumstance. To enhance the ability of line spectrum detection and increase the accuracy of frequency estimating, the adaptive frequency estimator was combined with an adaptive line enhancer with coherent adder. The simulation confirms its well performance of frequency estimating under low signal to noise ratio. Sea trial data analysis indicates that the very tow frequency line spectrums radiated by ships are quite stable and the frequency instability is within ±0.01 Hz.