Ocean Sound Speed Profile Measurement Using Echo Arrival Times

In many underwater acoustic applications, knowing the sound speed profile (SSP) is essential because it affects how acoustic signals travel and their strength. Currently, the SSP is measured directly by assessing sound speed or the related parameters of temperature, salinity, and depth. This paper discusses a method for remotely estimating the SSP using underwater acoustics. We introduce a pulse-echo technique that employs a narrow beam directional transmitter and two receivers to determine the sound speed. Our method relies on measuring the travel times of echo signals. Using synthetic signals modeled through a ray tracing approach, we show the effectiveness of our technique. The time of flight for the received signals is calculated using a cross-correlation technique. Comparisons of the estimated SSP with the assumed profile used to generate the synthetic signals confirm our method's accuracy.