Intercomparison between acoustic Doppler current profilers

Acoustic Doppler current meters have revolutionised current measurements and the number of instrument manufacturers is rapidly increasing. On the Scandinavian scene, mainly RD Instruments and NORTEK A/S try to win the favour of the large number of potential customers. Danish Hydraulic Institute has taken the opportunity to investigate the possible differences in measuring performance between the two products and deployed a WorkHorse 300 from RDI as well as an ADP 500 from NORTEK on the seabed within 50 meters from the authors´ long term monitoring site in Oresund in Denmark. A BroadBand ADCP from RDI has been measuring current at this site since 1992 and data from this instrument was taken as reference for the comparison between the WorkHorse and the ADP. The comparison revealed that although the two instruments aim at the same field of application and although they are comparable in price, there is a significant difference in performance. The main contributor to this difference is the different processing techniques employed by the two instruments. The paper documents that the broadband technique is superior to the narrowband in terms of precision and power consumption but the improvements comes at the cost of vertical measuring range