The former Ocean Physics Group led by Rob Pinkel, which has now grown into MOD, has long led the development of Doppler sonars, which measure the velocity of ocean flows by the phase shift of sound back-scattered from material within it.
A series of developments from the 1970’s led to the development of the commercial ADCPs that are now ubiquitous, and to the primary two Doppler operated by our group today:
The Revelle Hydrographic Sonar System (HDSS), a high power, two-frequency system that gives excellent vertical resolution in the upper 250 m and excellent range (~1000m) without sacrificing vertical resolution (Figure 1).
And our Phased-array Doppler sonars (PADS, Figure 2) which form swaths of beams, giving radial velocity in a fan or wedge (animation below). In Figure 2, our PADS was mounted on Research Platform FLIP, imaging surface waves as they propagated past.