Signal Processing of Radar Echoes Using Wavelets and Hilbert Huang Transform

Abstract

Atmospheric Radar Signal Processing is one field of Signal Processing where there is a lot of scope for development of new and efficient tools for spectrum cleaning, detection and estimation of desired parameters. The wavelet transform and HHT (Hilbert-Huang transform) are both signal processing methods. This paper is based on comparing HHT and Wavelet transform applied to Radar signals. Wavelet analysis is one of the most important methods for removing noise and extracting signal from any data. The de-noising application of the wavelets has been used in spectrum cleaning of the atmospheric radar signals. HHT can be used for processing non-stationary and nonlinear signals. HHT is one of the timefrequency analysis techniques which consists of two parts: Empirical Mode Decomposition (EMD) and instantaneous frequency solution. EMD is a numerical sifting process to decompose a signal into its fundamental intrinsic oscillatory modes, namely intrinsic mode functions (IMFs). A series of IMFs can be obtained after the application of EMD. In this paper wavelets and EMD has been applied to the time series data obtained from the mesosphere-stratosphere-troposphere (MST) region near Gadanki, Tirupati for 6 beam directions. The Algorithm is developed and tested using Matlab. Moments were estimated and analysis has brought out improvement in some of the characteristic features like SNR, Doppler width, Noise power of the atmospheric signals. The results showed that the proposed algorithm is efficient for dealing non-linear and non- stationary signals contaminated with noise. The results were compared using ADP (Atmospheric Data Processor) and plotted for validation of the proposed algorithm.