| acoustic device that determines the velocity of particles in the water volume by measuring the Doppler shift in the transmitted or scattered signal
Note 1 to entry: There are two classes of acoustic Doppler current profiler, based on backscattering or transmission.
Note 2 to entry: In the transmission-type of acoustic Doppler current profiler, bi-static measurements are typically made at distances of order of magnitude 10 cm along the beam's direction of propagation, but the signal actually represents the three-dimensional velocity of a small parcel of water, though it is considered to represent a point measurement.
Note 3 to entry: To determine a vertical profile of current with the transmission-type of acoustic Doppler current profiler, the device is lowered, or raised, through the water column, making a series of local measurements.
Note 4 to entry: In the backscattering-type of acoustic Doppler current profiler, a vertical profile of current can be determined remotely. The range of measurements is often of the order of tens to hundreds of metres depending on the acoustic transmission frequency.
Note 5 to entry: Note that the use in underwater acoustics of the words "transmit", "transmitter" and "transmission" to describe the process of sound radiation by a source is commonplace, but this deviates from the usage prescribed in IEV 702-02-05 where the words "emit", "emitter" and "emission" are preferred.
Note 6 to entry: This note applies to the French language only.