Active Time-reversal Based Target Localization In Complex Domain With DSLA

It is a challenge of underwater acoustic signal processing to detect a target in shallow water waveguide environments. In this dissertation, time-reversal transmit-receive interactive technology has been investigated based on DSLA (Double Spiral Line Array) for target three-dimensional localization to improve detection of a quiet target and enhance the perception of a small target.Active target detection faces the problem of reverberation suppression. This dissertation utilizes time reversal processing to suppress reverberation and improve echo-reverberation ratio. Time reversal processing (TRP) is equivalent to matched field processing with the known channel knowledge. However, the spatial temporal focusing of TRP is limited by environmental uncertainties. So robustness of time reversal processing has been investigated via iterative time reversal and time reversal operator decomposition.In fact, the marine environment and the acoustic field can be both characterized in the three-dimensional space. Target echoes contain three-dimensional location information of the target. Therefore, the DSLA can be used to localize the target in the three-dimensional space. In addition, the DSLA can obtain a large array gain and increase echo-reverberation ratio with more sensors in the limited physical aperture of an array.In complex domain, complete modeling of signal contains some properties such as improperty and noncircularity. So the information in the augmented domain can be used to further improve target detection capability. Target localization with high resolution can be achieved by combination of signal processing in complex domain and DSLA.Simulations and experimental results in a laboratory waveguide have demonstrated that target detection in complex domain with DSLA has higher three-dimensional accuracy in comparing with conventional active time reversal processing.