摘要
声多普勒流速剖面仪（ＡＤＣＰ）信号是一非平稳水声混响过程。我们用自适应格形滤波器估计它的谱。应用了三种程序，它们分别是随机梯度（ＳＧ）、快速卡尔曼滤波（ＦＫ）和递归最小二乘（ＲＬＳ）。在最佳参数的情况下给出了学习曲线。由这些学习曲线我们认为ＲＬＳ是最好的。它的收敛速度可与ＦＫ相比拟。但它的均方误差（ＭＳＥ）较小。用ＲＬＳ程序估计了ＡＤＣＰ信号的谱。随着运动介质非平稳性的增加，功率谱峰的数目可以是一、三或二，它们分别相应于介质运动的准平稳区、非平稳区或强非平稳区。这些与运动介质演化谱理论和Ｗｉｇｎｅｒ－Ｖｉｌｌｅ谱理论一致。在这些理论中，非平稳因子Ａ和特征宽度Ｂ两个都重要。当相应于散射体容积元的时间间隔Ｔ小于Ｂ时，可以设功率谱显示单峰特征，当Ｔ在Ｂ附近时，功率谱中有三个峰，当Ｔ大于Ｂ时，可以采用有两个峰的功率谱。
The spectra of acoustic Doppler Current profiler (ADCP) signal which is a non-stationaryunderwater sound reverberation process are estimated by adaptive lattice filter. Three programs, i. e.,stochastic gradient (SG), fast Kalman (FK) and recursive least square (RLS), are used. Learning curvesare given in the case of optimum parameters. From these curves we can conclude that, RLS program is thebest one. Its convergence speed is comparable with the one of FK, but its mean square error (MSE) is smaller than that of FK and SG. The speCtra of ADCP signal are estimated with RLS program. The number ofpower speCtrum Peaks may be one, three or two with increasing non-stationarity of medium movement,wthch correspond to the quasi-stationary area, non-stationary area and strong non-stationary area of medium movement, resistively. They are consistent with the theory of evolutionary spectra and Wigner-Villespectra of moving medium.In these theories, both the non-stationary factor A and characteristic width B are significant. When thetime interval T corresponding to the volume element of the scatters is smaller than B, we can suppose thatthe power speCtrum displays a single Peak characteristic, when T is in the neighbour of B, there are threePeaks in power speCtrum, and when T is latgen than B, we may use the power speCtrum which displays atwo Peak characteristics.
出处
《声学学报》
EI
CSCD
北大核心
1995年第2期81-87,共7页
Acta Acustica
