Figure 20.

A. End view of the acoustic transducers on an Acoustic Backscatter Sensor (ABS), each of different frequency (for example at 1.0, 2.5 and 5.0 Mhz). The ABS transducers emit pulses of high frequency sound which are reflected by suspended sediments in the water column. The ABS provides a profile of the intensity of reflected sound that is proportional to the concentration of suspended sediments. The calibration is frequency and particle-size dependent.

B. Side view of an Acoustic Backscatter Sensor(ABS) mounted on a tripod.