摘要
水声信道的典型特点是多途干扰强、多普勒频率偏移较大。水下移动目标因为多普勒的影响而无法实现正常的通信。本文提出了快速高精度多普勒估计算法(FHDSE),在保持多普勒频移高精度估计的同时,不需要很大的存储空间,同时计算复杂度较低,满足了相干水声通信系统的频率偏移的精度要求。FHDSE算法通过设计周期重复的多普勒估计信号,解决了水声多途信道的干扰;利用多组多普勒估计码,采用插值和加权平滑的方法,解决了相位卷叠现象,精确得估计出多普勒频率偏移。仿真和湖试结果均表明:该算法在载频为12KHz时,能够成功抵消12节航速引起的多普勒频移;信噪比8d B时,频偏精度达到0.25Hz。该算法在实际水声相干通信系统中得到很好的应用。
The UWA channel is characterized as a time-dispersive rapidly fading channel, which in addition exhibits Doppler instabilities. AUVs cannot communication due to the Doppler shift. This paper presents a fast high-precision Doppler shift estimation algorithm(FHDSE), which meets accuracy requirements of coherent acoustic communication system. This algorithm has the advantage of high precision of frequency offset estimation, while it requires small storage space and lower computational complexity. To solve the multipath channel interference, FHDSE introduces periodic Doppler compensating code. Meanwhile, it adopts interpolation and weighted smoothing method to solve the phase folding phenomenon and improve the precision of the Doppler frequency shift estimation. The simulation and lake trial data processing results show that: the algorithm can successfully offset Doppler shift caused by 12 knots and is suitable for coherent underwater acoustic communication. When the SNR is 8d B, the Doppler shift estimation precision is up to 0.25 Hz.
引文
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