Ever noticed that the GPS location on your smartphone isn’t all that smart? For example, sometimes your smartphone claims you are in the duck pond when in fact you are on the other side of the park and can’t even see the duck pond? But now, thanks to a research conducted at the University of Otago, New Zealand, in collaboration with Curtin University, Australia, the accuracy of the global positioning system (GPS) in smartphones can be significantly improved.
By combining signals from four different Global Navigation Satellite Systems (GNSSs), Otago’s Dr Robert Odolinski and Curtin University colleague Prof Peter Teunissen, have demonstrated that it is possible to achieve centimeter-level precise positioning on a smartphone. According to Dr Odolinski, it’s all down to the mathematics they applied to make the most of the relatively low-cost technology smartphones use to receive GNSS signals, combining data from American, Chinese, Japanese, and European GNSS. They believe this new capability will revolutionize applications that require cm-level positioning.
According to him, to understand the new technology, a look back at the historical scientific context is needed. For decades, construction, engineering, cadastral surveying and earthquake monitoring have relied on high-cost, ‘dual-frequency’, GPS positioning to obtain centimeter-level location information. The challenge is that GPS signals, traveling from Earth-orbiting satellites to receivers on the ground, are disrupted along the way, and this generates errors which limit precision. The traditional solution is to combine GPS signals sent at two different frequencies to improve the positions, but the antennas and receivers required have been expensive, far beyond the reach of many who would benefit from the technology.
The new approach uses only one of two frequencies but collects data from more satellites, for what is called a “multi-constellation” GNSS solution. The extra data (and clever math) is used to improve the positions without adding cost. What Dr Odolinski and Prof Teunissen have now shown is that this approach can work in smartphones too, producing competitive results compared to dual-frequency GPS solutions. Dr Odolinski believes that countries and industries of all sizes can benefit from using smartphones as GNSS receivers, and is confident commercial application and development will lead on from this research. This significant reduction in costs when using smartphones can increase the number of receivers that can be deployed, which will revolutionize a range of disciplines requiring centimeter-level positioning, including precise car navigation, surveying, and geophysics (deformation monitoring), to name a few.
Paper: An Assessment of Smartphone and Low-Cost Multi-GNSS Single-Frequency RTK Positioning for Low, Medium and High Ionospheric Disturbance Periods
