FAM和SSCA算法的matlab源程序-detection and identification of signal
FAM和SSCA算法的matlab源程序-detection and identification of signalFAM和SSCA算法的matlab源程序-detection and identification of signalDISCLAIMER NOTICEMTHIS DOCUMENT IS BESTQUALITY AVAILABLE. THECOPY FURNISHED TO DTICCONTAINED A SIGNIFICANTNUMBER OF PAGES WHICH DONOT REPRODUCE LEGIBLY.ilApproved for public release; distribution is unlimitedDETECTION AND IDENTIFICATION OF CYCLOSTATIONARY SIGNALSEvandro luiz da costaLieutenant Commander, brazilian NavyB.S., Instituto Militar de Engenharia, 1980Submitted in partial fulfillmentof the requirements for the degree ofMASTER OF SCIENCE IN ELECTRICAL ENGINEERINGANDMASTER OF SCIENCE IN ENGINEERING ACOUSTICSfrom theNAVAL POSTGRADUATE SCHOOLMarch 1996Author.Evandrodk da costaapproved byRQ求Ralph Hippenstiel, Thesis Co-AdvisorRoberto Cristi, Thesis Ca-AdvisoiHerschel. Loomis, Jr, hairmanDepartment of Electrical and Computer EngineeringArthony A. Atchley / ChairmanEngineering Acoustics Academic CommitteeABSTRACTPropeller noise can be modeled as an amplitude modulated(AM) signalCyclic Spectral Analysis has been used successfully to detect the presence ofanalog and digitally modulated signals in communication systems. It can also identithe type of modulation. Programs for Signal Processing based on compiledlanguages such as FORTRAN or C are not user friendly, and MATLAB basedprograms have become the de facto language and tools for signal processingengineers worldwideThis thesis describes the implementation in mAtlab of two fast methods ofcomputing the Spectral Correlation Density(SCD)Function estimate, the FFTAccumulation Method (FAM)and the Strip Spectral Correlation Algorithm( SSCA),toperform Cyclic Analysis. Both methods are based on the Fast Fourier transformFFT)algorithm. The results are presented and areas of possible enhancement forpropeller noise detection and identification are discussedTABLE OF CONTENTSINTRODUCTIONA MOTIVATION,P,中“····*s···:···:B BACKGROUNDC THESIS GOALSIL NOISE IN THE OCEAN··+A TYPES OF UNDERWATER NOISE25561. Ambient Noise番申2. Self noise3. Radiated noise8B RADIATED NOISE FROM SHIPS, SUBMARINES AND TORPEDOES.......8C PROPELLER NOISE10lI CYCLOSTATIONARY PROCESSING15A CYCLOSTATIONARIT15B THE CYCLIC AUTOCORRELATION FUNCTION (ACF)17C THE SPECTRAL CORRELATION DENSITY FUNCTION (SCD)18N. ESTIMATION OF THE SPECTRAL CORRELATION DENSITY FUNCTION23A FFT ACCUMULATION METHOD(FAM)25B STRIP SPECTRAL CORRELATION ALGORITHM(SSCA■D28V. EXPERIMENTAL RESULTSA. ANALOG-MODULATED SIGNALS311. Amplitude Modulated(AM)Signal===2-312. Pulse-Amplitude Modulated(PAM) Signal58B DIGITAL-MODULATED SIGNALS1. Amplitude Shift Keying(ASK) Signal中中非昏号即即号自唱即自曲音非带卡.最662. Binary-Phase Shift Keying(BPSK) Signal6了VI CONCLUSIONS81A SUMMARY81B SUGGESTIONS82APPENDIX A-CALCULATION OF THE SCD FUNCTION OF AN AMPLITUDE-MODULATED SIGNAL83APPENDIX B-FUNCTION AUTOFAM95APPENDIX C-FUNCTION AUTOSSCA99APPENDIXD-FUNCTION CROSSFAM103APPENDIX E-FUNCTION CROSSSSCA109APPENDIX F-PLOTTING ROUTINES113LIST OF REFERENCES115INITIAL DISTRIBUTION LIST看音117INTRODUCTIONA. MOTIVATIONPropeller related acoustic signatures typically exhibit modulationcharacteristics. These modulation characteristics originate from the cavitationprocess that takes place in the water due to the cyclic movement of the propellerThe cavitation process is basically the collapse of air and vapor bubblesdue to variations in the static pressure. These variations in static pressure are aconsequence of the passage of the propeller blades through the water. Thismovement, cyclic in nature, causes amplitude modulation in the static pressureand as a consequence an amplitude-modulated(AM) signal can be detected in areceiverCyclostationary processing techniques have been used to detect andlentify analog and digital communication signals very successfully. Thesetechniques have the advantage of using a more realistic model for the signalthan the stationary model used in most of the more conventional signalprocessing techniquesB BACKGROUNDThe basic elements of cyclic spectral analysis are the time-variant cyclicperiodogram and the time-variant cyclic correlogram. These two functions form aFourier transform pair. This fact is known as the cyclic Wiener relation or thecyclic Wiener-Khinchin relation [Ref. 1: p. 49.1
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