Assessing absolute and relative accuracy of recreation-grade and mobile phone GNSS devices: a method for informing device choice

The affordability/availability and portability of recreation-grade receivers and mobile devices, compared with commercial survey Global Navigation Satellite Systems (GNSS), commonly referred to as Global Positioning System, make them worthy of consideration for student fieldwork and research. While empirical evidence of the relative accuracy of low-cost GNSS receivers in open areas is currently limited, initial findings suggest that levels of relative accuracy, as opposed to absolute accuracy, make these devices an inexpensive and manageable technology for measuring the relative location of land features. Given the current speed at which GNSS technology advances, it is important to have an appreciation of any proposed device's accuracy. This paper presents a method for evaluating the levels of absolute and relative accuracy of various devices, which can inform the choice of device for particular survey-based projects. It can also be used to indicate a best practice' approach to using GNSS devices in a research and study context, through an assessment of the factors influencing levels of relative accuracy, such as the length of time a device is left to settle before recording a point. In addition, this method can be a useful exercise in and of itself for helping students better understand absolute and relative accuracy, the capabilities of their own mobile hardware, and the potential use of recreation-grade and mobile devices in a range of scenarios both within and beyond the academy.