Low Cost and IoT Magnetometer for Underwater Applications

Abstract

Magnetometers are essential tools in our understanding of Solar-Terrestrial interactions. Solar activity, such as solar storms or solar energetic particles (SEP), may damage our infrastructure and lead to energy and communications blackouts, potentially generating a huge economic burden. With the help of magnetometers we can analyse changes in the Earth’s magnetic field, and, thus, mitigate the negative effects of space weather. Although we have sophisticated instruments to measure the Earth’s magnetic field we are still limited by the amount of area we can cover. Commercially available scientific magnetometers are expensive, hence, making it challenging to deploy large numbers of them throughout the globe. In addition, maintaining them requires time, effort, knowledge, and money. Furthermore, accessing the data is not always straightforward. Having a broad coverage of magnetic instruments around the globe may help us understand not only solar-terrestrial interactions, but it may also help us understand the Earth’s inner core, animal migration behaviour, or other unknowns such as the influence of the solar cycle variation on the Earth’s climate, or the polarity flip of the Earth’s magnetic field. This will consequently help us prevent and mitigate the effects of natural disaster.

This thesis aims to develop a breadboard prototype of a high-quality, low-cost, and easily replicable magnetometer for underwater applications that provides real-time data access in order to facilitate worldwide deployment of magnetic instruments and help achieve global coverage of magnetic field observations. The prototype includes three low-cost single-core fluxgate magnetic sensors in conjunction with six low-pass-filters and a 24-bit analog-to-digital converter, and an Arduino board as a microcontroller. It allows real-time data access through the use of a cellular network and an IoT (Internet of Things) analytics platform, and it aims to enable underwater capability by tracking the magnetometer movements in the water and by further applying a coordinate frame transformation.

The observations show that while a resolution smaller than 0.1 nT is possible, higher quality sensors, such as ring-core fluxgate sensors, are needed if increased accuracy and precision are desirable. The simulation results show that the algorithm implemented for correcting the difference in orientation of the instrument with re- spect to the Earth’s frame of reference, would accurately correct the measured field while moving underwater. These results demonstrate that a low-cost high-quality instrument with real-time data transmission is possible, thus, facilitating global deployment of magnetometers, and as a result, the increase of world coverage of magnetic observations.