Investigation of the two pulse correlation sonar technique for water current measurement

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dc.contributor.authorHuber, Benedikt Theodoren_US
dc.date.accessioned2024-08-14T17:26:01Z
dc.date.available2024-08-14T17:26:01Z
dc.date.copyright1986en_US
dc.date.issued1986
dc.degree.departmentDepartment of Physics
dc.degree.departmentDepartment of Physics and Astronomy
dc.degree.levelMaster of Science M.Sc.en
dc.description.abstractIn this thesis the use of the two pulse correlation sonar technique for measuring water currents in the ocean is investigated. New theoretical analysis is developed to study the operation of the two pulse correlation sonar, including in particular, different de­-modulation techniques, the effect of cross-pulse interference on the correlation coeffi­cients and correlation accuracy estimates. New theory shows that the effect of having two acoustic pulses in the water at the same time is equivalent to having a single pulse acoustic signal returning from ran­dom scatterers with a signal to noise ratio of one. The peak of the spatial correlation function of the scattered signal is lowered by the presence of this noise. A new treat­ment of spread spectrum pulses, used to reduce the interpulse interference, is shown to be only of limited usefulness. Literature does not mvest1gate the effect of the low signal to noise ratio on the spatial correlation function, for different demodulation techniques. Different demodula­tion techniques evaluated in this thesis, namely complex demodulation, clipped com­plex demodulation and amplitude demodulation are affected differently by the low sig­nal to noise ratio and will result in different spatial correlation functions. The theoretical accuracy of the water velocity estimate is determined by two fac­tors. The height of the correlation peak and the accuracy of each correlation value. The height of the correlation peak is determined by the signal to noise ratio and by the demodulation technique, while the accuracy of the correlation values is determined by the bandw1dth-mtegrat1on time product of the time series that is correlated The peak of the correlation function for water volume return drops to O.5 for complex demodulation, while 1t drops to O.25 for amplitude and clipped complex de­modulation, which has not been previously shown m available literature. If the two returning pulses are well separated in time, such as a signal returning from the bot­tom, then the correlation peak for all three demodulation techniques is equal to one. The new theoretical predictions of correlation sonar performance for vol­ume scatterers are confirmed with a series of experiments earned out in Saanich Inlet, British Columbia and using a computer model of the correla­tion sonar. Theory and experiments confirm that a current measuring two pulse correlation sonar can be constructed and will give accurate velocity estimates.en
dc.format.extent134 pages
dc.identifier.urihttps://hdl.handle.net/1828/18235
dc.rightsAvailable to the World Wide Weben_US
dc.subjectUN SDG 14: Life Below Wateren
dc.titleInvestigation of the two pulse correlation sonar technique for water current measurementen_US
dc.typeThesisen_US

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