Design and Evaluation of a Compact Correlation Velocity Log for Small Underwater Vehicles

The correlation velocity log (CVL) is an acoustic navigation aid that exploits the spatial coherence of seafloor scattering to estimate the motion of an array relative to the seafloor. Accurate velocity estimation from a CVL is closely tied to the array geometry, requiring large and densely packed receive arrays in order to operate over a range of conditions. This paper presents an alternative operating paradigm, the spatial-temporal CVL, that blends both spatial and temporal velocity estimation techniques to allow accurate navigation from sparse arrays. By trading hardware complexity for signal processing complexity, a spatial-temporal CVL is well suited to small platforms that operate in shallow water for which other navigation aids may be unsuitable. A prototype array was developed and evaluated at Seneca Lake, New York over a range of operating conditions. The experimental results demonstrate the viability of this type of sensor as an acoustic navigation aid and illustrate some of the important considerations in the design.