Very good catch spooky, it was Shell and Flotation Tech (and others) that built and tested the first up/down looking ACDP system. That is the type system we shipped 8-14 imo. Now they use fiber optic instead of the modems.
Shell Global Solutions (US) and RD Instruments, working in co-operation with Floatation Technologies, Linkquest, and Evans-Hamilton, set about designing a downward/upward-looking system for offshore operations. A validation test for this configuration was performed in the Gulf of Mexico, where Shell Oil was drilling from the Transocean Sedco Forex Deepwater Nautilus semi-submersible in 1574m water depth. The rig was already fitted with an RDI 75kHz Vessel Mounted (VM) downward-looking ADCP mounted in the rig’s port pontoon some 9m below the surface. This current profiler provided real time data for the top 600 – 800m of water. #msg-31462841