Fixed Echo Rejection in Sodar Using Noncoherent Matched Filter Detection and Gaussian Mixture Model-Based Postprocessing
Fixed Echo Rejection in Sodar Using Noncoherent Matched Filter Detection and Gaussian Mixture Model-Based Postprocessing
复制标题
使用非相干匹配滤波器检测和基于高斯混合模型的后处理修复声雷达中的回声抑制
DOI：
10.1175/jtech-d-18-0095.1
复制
发表时间：
2019
影响因子：
2.2
通讯作者：
Kendrick P
中科院分区：
文献类型：
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作者：
Kendrick P
多普勒声雷达是一种用于对低行星边界层进行声学遥感的技术。声雷达通常用于测量风廓线;然而，它们受到噪声（声学和电学）和来自固定物体的回波造成的问题的困扰，这可能会使径向速度估计值产生偏差。研制了一台具有64个独立通道的双基地声雷达。该设备可以实现灵活的波束形成;波束可以以与频率无关的相同角度倾斜，这是大多数商业设备的限制。本文提出了一种基于多频步进线性调频脉冲的风廓线声雷达信号处理算法。采用非相干匹配滤波器对回波信号进行分析。非相干匹配滤波器将来自多个频率的径向速度估计组合成单个优化。为了识别和分离后向散射源、噪声源和固定回波源，采用随机模式识别技术高斯混合建模对非相干匹配滤波数据进行后处理。该方法允许识别和分离不同的随机过程。在识别之后，噪声和固定回波分量被去除，并且产生干净的风廓线。该技术与传统的基于频谱的径向速度估计方法进行了比较，并证明了在抑制固定回波分量方面的改进;这是位于复杂地形和城市环境中时声雷达性能的主要限制之一。
Doppler sodar is a technology used for acoustic-based remote sensing of the lower planetary boundary layer. Sodars are often used to measure wind profiles; however, they suffer from problems caused by noise (both acoustic and electrical) and echoes from fixed objects, which can bias radial velocity estimates. An experimental bistatic sodar was developed with 64 independent channels. The device enables flexible beamforming; beams can be tilted at the same angle irrelevant of frequency, a limitation in most commercial devices. This paper presents an alternative sodar signal-processing algorithm for wind profiling using a multifrequency stepped-chirp pulse. A noncoherent matched filter was used to analyze returned signals. The noncoherent matched filter combines radial velocity estimates from multiple frequencies into a single optimization. To identify and separate sources of backscatter, noise, and fixed echoes, a stochastic pattern-recognition technique, Gaussian mixture modeling, was used to postprocess the noncoherent matched filter data. This method allowed the identification and separation of different stochastic processes. After identification, noise and fixed echo components were removed and a clean wind profile was produced. This technique was compared with traditional spectrum-based radial velocity estimation methods, and an improvement in the rejection of fixed echo components was demonstrated; this is one of the major limitations of sodar performance when located in complex terrain and urban environments.