Real-time Wave Monitoring on Coastal Areas Using LPWAN-Based Embedded Systems

A new embedded system is presented for real-time wave monitoring on coastal areas using SigFox communication. SigFox is a Low-Power Wide-Area Network technology that has been rarely used in coastal marine monitoring. The system is based on the low-power TD1205P module that includes a microcontroller, an accelerometer, a GNSS receiver and a SigFox transceiver. Each hour, the module estimates the wave's maximum height ($H$max) and mean period (Tz), determines the GPS position, and wirelessly transmits the data through the SigFox network. The procedure for wave parameter estimation is based on the zero-upcrossing method using the vertical acceleration data. It was experimentally validated by attaching the embedded system to a moored buoy and comparing $H$max and Tzwith that provided by a seafloor acoustic wave and current profiler, used as a reference. Results over a period of two months show a good match for $H$max but less for Tz, which crosscorrelation values at zero lag of about 0.85 and 0.5, respectively. Power tests of the embedded system were also performed resulting in a lifetime estimation of 420 days with a battery pack of 3 Ah.