The patented sensor measures a vertical turbidity profile through the water / sediment interface, and estimates the level of the bottom with sub-millimeter resolution. The SM3 is also offers burst sampling of the level. The SM4 instead features nephelometric turbidimeters, fluorescence meters, accelerometer, conditions-based monitoring, and UV anti-fouling.
To convert the turbidity data to suspended sediment concentration (SSC) one must take a sample of the latter. The Nilsson sampler is a light-weight (11 kg) sampler that nonetheless is useful in up to 200 cm/s stream velocity.