Advances in Doppler sonar technology

There has been significant recent progress in the development of Doppler sonar systems for marine research. Major advances include the development of side-scan Doppler systems for surface wave, ship wake and Langmuir cell research, the development of coded pulses for improved sonar precision, and the development of phased array Doppler sonar for 3D (x,y,t) imaging of flow fields. Major challenges remain to understand the detailed behavior of the physical and biological scatterers on which these systems rely. Further effort is required to develop instruments which are robust with respect to clutter from river bottoms, ice keels, etc. As these issues are resolved, the role of acoustic remote sensing in both environment monitoring and scientific research should expand.