This Phase I proposal is to establish the feasibility of developing a velocity log suited to navigation of small underwater vehicles that are required to transit to the littoral zone from deeper open ocean waters during clandestine operations. The instrument will measure three components of bottom- and water-relative velocity over a wide altitude range of less than 1 to greater than 1000 m. It will be accurate, small, light-weight, and use little average power. We propose an innovative hybrid design combining several technologies we have already developed. As correlation velocity log (CVL) technology is ideally suited to achieving high altitude bottom-tracking with a limited aperture, we will scale down and update our 22 kHz CVL to a frequency between 38 and 75 kHz. Accuracy and covertness concerns at low altitudes motivate us to add a Doppler velocity log transducer (probably a 2D phased array operating at 600 kHz), with shared electronics in the hybrid system minimizing size and weight. During Phase I we will design the hybrid velocity log sonar, validate the concept, and specify a prototype to be built and further developed in Phase II.
Keywords: Doppler Velocity Log, Correlation Velocity Log, Velocity-Aided Inertial Navigation, Dead-Reckoned Navigation, Underwater Vehicle, Bottom-Track Velocity, Sonar.
