Time of arrival estimation using fast fourier transform overlap for underwater distance measurement

This paper presents an underwater acoustic distance measurement system based on Fast Fourier Transform (FFT) overlap. The low-cost underwater communication device is developed to achieve the objective. The time-of-arrival (TOA) technique is used to estimate the distance between the transmitter and receiver. The TOA estimation is derived based on the intensity of the received signal with frequency of interest. The extraction of the signal from the receiver is performed by using digital signal processing algorithms. FFT is used to convert the receiving signal from time domain into frequency domain for extracting the information of signal (relevant frequency and amplitude). Hence, TOA estimation can be obtained from the frequency information using overlap transform processing. This enables the increase of the TOA measurement resolution with the overlap technique. Trilateration algorithm is also employed as to determine the relative position of underwater target based on distance measurement. This approach is tested on shallow underwater to estimate the position of target. The experimental results are presented to demonstrate its capabilities.