Underwater Wideband Signals Based On The Wavelet Transform

In underwater signal processing system, homing signals decide processing means and system performance. For gaining farside effecting distance and upper distinguish,we usually use wideband signals.But wideband signals are typically nonstationary signals, Fourier Transform is not suitable for this signals.In nonstationary signals processing,Time-Frequency analysis is effective to deal with the signals.In this paper we research underwater objects wideband signal detection and estimation mainly.For adapting to underwater nonstationary environment I select one of Time-Frequency tools - wavelet theory to solve signal detection and estimation.The major content is following:1. Discuss the Time-Frequency analysis, Short-Time Fourier Transform and wavelet theory.Also do some compare and analysis on wavelet theory and the traditional Fourier Transform.which is the base of the whole project.2. Study wideband signals definition and Wideband Ambiguity Function. Many typical wideband signals is analyzed qualitatively with Wideband Ambiguity.3. The computation structure of Continue Wavelet Transform is studied.Fast algorithms based on FFT and Mellin Transform are proposed,which can realize the fast wideband correlation processing.4. The wideband active signal detector based on Wavelet Transform is presented and simulation is given.The Two-Dimensional Cross-Correlation detector baseded on Wavelet Transform is introduced .The simulating result proves this detector is efficient.5. The wavelet estimating performance is analyzed form Time Delay estimation, Doppler estimation and Time Delay and Doppler joint estimation.for improving on estimating performance,The new wavelet estimator based on generalized correlation is presented. The simulating result proves this estimator is efficient.