Use of Variable Threshold Detection in Time of Arrival Measurements for SBL Underwater Acoustic Positioning Systems

Underwater acoustic positioning systems (UAPSs) are used to know the positions of underwater vehicles and sensors. In short baseline (SBL) acoustic positioning systems, the three-dimensional position is localized by the measured distances, where the distance is obtained by estimating the time of arrivals (TOAs). In underwater acoustics, the TOA measurement errors are caused by acoustic reflection and ambient noise. The typical TOA measurement is done by detecting the time location of the maximum correlation peak. This peak detection causes a measurement error when the first peak is not the maximum amplitude. We propose the variable threshold detection to keep high positioning accuracy in highly reflective and noisy environments. The results of our simulation and experiment have proved the effectiveness of the proposed method.