Oversampling MAVS for reduction of vortex-shedding velocity-sensing noise

Reduction of vortex-induced velocity-sampling noise was demonstrated in an acoustic travel-time current meter, MAVS, by oversampling and averaging bursts of 20Hz measurements every 0.5s sampling interval during tows in the Woods Hole Oceanographic Institution flume. A characteristic vortex size of 7.37cm (from frequency and tow speed) translated into narrow band spectral peaks of velocity fluctuation with frequency proportional to tow speed. A selection of burst-sampling intervals during which 20Hz measurements were averaged was tuned to the profiling speed of the moored profiler upon which the MAVS was to be mounted. Burst-sampling improved the signal to noise ratio by almost a factor of 3 with a 4-point burst every 0.5s at 30cm/s tow (profiling) speed. This closely matched the dominant 4.3Hz vortex at 30cm/s tow speed.