SDI-12 based turbidity measurement system with field calibration capability

Turbidity is a measure of how much the material suspended in water decreases the passage of light through the water. In order to carry out accurate turbidity measurements, turbidity-measuring probes require periodic calibration. Classical calibration implies manual. procedures characterized by long calibration time, additional common errors and lower repeatability. The paper presents a distributed turbidity measurement system with field calibration capabilities. The main system elements are turbidity probes, one calibration unit RS232 compatible, three RS232 to SDI-12 converters and a notebook PC. The acquisition and control tasks of the turbidity measurement probes and field calibration unit are implemented using a microcontroller (PIC16F877).