Easy to build low-power GPS drifters with local storage and a cellular modem made from off-the-shelf components

Abstract

Drifters that track their position are important tools in studying the hydrodynamic behavior of rivers. Drifters that can be tracked in real time have so far been rather expensive. Recently, due to the rise of the open-hardware revolution and the associated Arduino ecosystem, both GPS receivers and cellular modems have become available at lower prices to "tinkering scientists", i.e., scientists that like to build their own measurement devices as much as is possible. This article serves two goals. Firstly, we provide detailed instructions on how to build a low-power GPS drifter with local storage and cellular model that we tested in a fieldwork on the confluence of the Chindwin and Ayeyarwady rivers in Myanmar. The device was designed from easily connected off-the-shelf components, allowing construction without a background in electrical engineering. The instructions allow fellow geoscientists to recreate the device. Secondly, we set the following question: has the open-hardware revolution progressed to the point that a low-power GPS drifter that wirelessly transmits its position can be made from open-hardware components by most geoscientists?. We feel this question is relevant and timely as more low-cost open-hardware devices are promoted, but in practice applicability is often restricted to the "tinkering engineer". We argue that because of the plug-and-play nature of the components geoscientists should be able to construct these type of devices. However, to get such devices to operate at low power levels that fieldwork often demands requires detailed (micro)electrical expertise.