Research On LFM Singal Processing By Single Vector Hydrophone And FRFT

Presently，it is a very practicality and popularity engineering application that usingsingle vector hydrophone as sonar receiver at domain of underwater acoustic. Single vecorhydrophone signal processing becomed a very important problem and research field atdomain of underwater acoustic signal processing.Linear Frequency-Modulated (chirp,LFM) signal detection and azimuth estimation isa important subject for passive sonar signal processing.For LFM signal, it can not improveSNR that only reduce process bandwidth. For single vector hydrophone,the space gain islimited,the detection and azimuth estimation capability for LFM signal will fall at lowSNR.The basic principles of vector signal processing are reviewed at first in this thesis.Then,this thesis analyzed method of popularity LFM signal processing in common useused in processing LFM as single vector hydrophone, such as Short Time FourierTransform(STFT),Wigner Ville Distribution (WVD),Wavelet Transform(WT),FractionalFourier Transform (FRFT),and analyzed those predominance and shortcoming.At basin onthose analyse,this thesis advance a method that use FRFT in single vector signalprocessing. First,this method estimate the careless value of chirp ratio approximately intime-frequency domain for reducing confines of fracional order,and then filter LFMsignle in fracional order field, advance LFM signle’s SNR, estimate the exactitude value ofchirp ratio approximately and using FRFT at the LFM signle,and then estimate the signalazimuth by acoustic intensity in fracional order field.As result of emulate data and ocean examination data processing,those methodswould effectively increase the capability that single vector hydrophone detection andazimuth estimation for LFM signal.At one moment,this method used STFT for pre-processaccord flow of modern times sonar signle processing,and compute quantity is on the smallside.This method has basically solved compute quantity hugeness matter for FRFT processLFM signle search in2-D time-frequency plane,this method has application value onengineering practice.