An Acoustic Doppler Current Profiler is referred to by the acronym ADCP, however, the name ADCP is a trademark of RD Instruments. Other manufacturers, herefore, use different trademark names. Acoustic Doppler Current Profiler instruments are used to measure the speed of water across an entire water column and also at equal intervals over the water column.

Generally the instrument is mounted vertically - facing upwards or downwards. However, the technology makes it possible for manufacturers to cater to different applications. For instance, the instrument can also be mounted horizontally, to measure the current profile from one side to the other side of a waterway. A number of instruments are particularly suitable for vessel (hull) mount. When interfaced to surface positioning systems you can take constant current profiles from the water column when sailing.

The various applications require the manufacturer to develop techniques to adhere to specific circumstances which the instrument has to measure. For instance, for vessel mount systems, the instrument should be capable of tracking the bottom profile (bottom track). Instruments equipped with surface tracking devices are able to accurately measure the currents in surface layers even when the water level changes due for example, to tide. The technology also has resulted in further development of algorithms which allow computing wave spectrum data from Current Profiler data.

Due to the typical applications and hence their specifications, a direct comparison is difficult to make between the available current profilers. In general, all instruments are able to measure small scale current at various distances up to 800m from the instrument. Obviously the systems which operate at low frequencies provide the biggest range while high frequency systems yield more precise data.

Incorporating additional sensors such as Turbidity, Oxygen, etc. makes the instrument very valuable for applications where environmental data at the instrument location is to be collected as well. It is up to you to find out which system suits your application requirements best.

Hydro international is much indebted to all the manufacturers who contributed to our Product Survey and answered the many questions about their systems.