| acoustic device that determines its own velocity by measuring the Doppler shift of echoes from the bottom|
Note 1 to entry: A Doppler velocity logger can be combined with an acoustic Doppler current profiler. When such a system is mounted on a moving ship, the bottom track velocity can be subtracted from the measured water velocity to give the net current profile.
Note 2 to entry: A correlation velocity logger is a related device that typically transmits two pulses at different positions. By virtue of being on a moving platform, the device uses the change in correlation between the two received signals to infer the platforms' velocity.