基于小波变换的ICESAT-GlAS波形处理

ICESAT-GLAS data processing based on wavelet transform

小波变换在信号处理方面的优势越来越明显,但是小波中的小波基不是唯一的,所以采用不同的小波基即使处理同一组数据其结果也会不同。为了确定那种小波基更适合于大光斑激光雷达,通过对MATLAB中常用的小波基参数特性的比较分析最终确定选用Daubechies小波基和Symlets小波基,并分别通过对ICESAT-GLAS波形进行小波分解、阈值处理和小波重构来实现波形去噪过程。结果表明:用Symlets小波基中的sym7小波基比用Daubechies小波基中的db1小波基去噪后波形信噪比要高,而均方根误差则比用Daubechies小波基中的db1小波基的低,由此看来Symlets小波基中sym7小波基更适合于处理大光斑激光雷达波形数据。

The advantage of wavelet transform on signal processing is increasingly obvious.Since the wavelet basis isn＇t unique,the results derived from the same data by different wavelet basis may be various.In order to know which wavelet basis is appropriate for ICESAT-GlAS data,this paper chooses Daubechies wavelet basis and Symlets wavelet basis according to the comparison and analysis on the characteristics of eight common wavelet basis parameters in MATLAB,and achieves the denoised wave by the decomposition,setting threshold function,and re-constructing to the data about the shape of echo wave from ICESAT-Glas.The conclusions are the SNR of the data processing using Sym7 of Symlets wavelet basis is higher than that using db1 of Daubechies wavelet basis,while the RMS error is lower than that using db1.Thus,Sym7 wavelet is the right one to process the data of ICESAT-GlAS.