Measurement of pH Water Based on Sensor, Arduino and Solar Cell in Laser Communication

We connected $\mathbf{p H}$ sensor and solar cell into Arduino Board to control data transmission via red laser communication or popular known as visible light communication (VLC). The sensor was calibrated through pH water solution measurement compared with conventional $\mathbf{p H}$ Meter. This sensor collected and then modulated $\mathbf{p H}$ data in Arduino to be sent via laser beam. The beam is captured by solar cell which acts as a photodetector in receiver. The received data will be demodulated in Arduino to be displayed in serial monitor to observe the communication performance. As the result, the link distance of laser communication can reach 35 m using 1-PWM and 15 m using 2-PWM, in freespace environment. When the transmission channel was changed into water environment, the link distance will decrease severely. The prototype output of this work will be a future self-powered modem for water surface and underwater monitoring system.