Design of a pseudo-holographic distributed time-of-flight sonar range-imaging system

The design of an audible sonar distributed sensor time-of-flight range imaging system is investigated, sonar being chosen as a substitute for optical range imaging due to cost and simplicity of implementation. The distributed range imaging system proposed is based on the holographic principle where the sensors detect the self interference of the reflected sound from the scene, and the Fourier analysis computes the reflected object profile. An approximate linearised model used in related holographic imaging techniques is found to be inappropriate for the design, and qualitative assessment of simulations show that removing the linearisation dramatically improves image reconstruction. Quantitatively the nonlinear reconstruction improves the RMSE by a factor of 1.3-2.1 times. The full nonlinear reconstruction is slow, and mathematical development lead to 15 fold reduction in computation time.