시역전처리에서 센서배열 최적화 및 수중통신 적용

Abstract

Time reversal processing is useful in diverse areas, such as reverberation nulling, target echo enhancement and underwater communication. In underwater communication, the bit error rate has been improved significantly due to the increased signal to noise ratio by spatio-temporal focusing.

This dissertation deals with the optimization of array configuration in time reversal processing which can provide better performance with optimal number of array element. The formulation which is based on the genetic algorithm maximizing the contrast between the foci and area of interest as an objective function is applied to determine the optimal location of array element and optimal number of element. In addition, the developed algorithm was applied to the matched field processing with ocean experimental data for verification. The sea-going data and simulation showed almost 3dB improvement in the output power at the foci when the array elements were optimally distributed. The rule of thumb which is the optimal configuration of array as a function normalized depth and normalized spacing is derived in the event. It is shown that the optimal spacing of sensor at the time reversal processing is twice of wave length by the numerical simulation and the theory of normal mode in the shallow-water waveguide.

Lastly, the effect of optimal array configuration in underwater acoustic communication with passive time reversal is examined in order to assist developing underwater communication system. According to the simulation, the optimal configuration of the array is also observed in underwater communication.