基于对数自适应算法的大气噪声抑制及其传输系统仿真

Simulation of atmospheric noise suppression and transmission system based on logarithmic adaptive algorithm

为有效分析大气噪声等冲击性噪声对水下超低频通信的影响和改进对数自适应算法的有效性,搭建turbo码(MSK)传输系统,利用传输系统中的误比特率曲线性能作为评价指标,这种评价方法与传统算法收敛性曲线相比,更能真实客观地反映通信质量。但需要指出,在特定信噪比条件下研究雷电等冲击性噪声时,会出现加噪声后通信质量变好的情况,这与实际情况不符,因此需要在对雷电的噪声模型进行分析讨论后,对合适模型的噪声功率进行合理的理想化处理。经实验验证,若保持误比特率10-4不变,加入雷电噪声后需要额外4.5 dB左右的功率,运用对数自适应算法处理后可以节约这些功率。

A turbo code(MSK)transmission system is built to effectively analyze the influence of impact noises(atmospheric noise,etc.)on the underwater ultra⁃low frequency communication and improve the effectiveness of logarithmic adaptive algorithm.The curve performance of bit error rate(BER)in the transmission system is used as the evaluation index.In comparison with the convergence curve of the traditional algorithm,this evaluation method can reflect the communication quality more truly and objectively.However,when studying impulse noises(lightning,etc.)under a specific signal⁃to⁃noise ratio(SNR)condition,the communication quality will become better after adding noise,which is inconsistent with the actual situation.Therefore,after analyzing and discussing the noise model of lightning,it is necessary to idealize the noise power of the appropriate model reasonably.The experimental results show that,if the BER is kept at 10-4,the additional power of about 4.5 dB is needed after adding the lightning noise,which can be saved by the logarithm adaptive algorithm.