Evaluation of positioning accuracy with the use of sports watches equipped with GNSS modules

It is difficult to imagine today's world without Global Navigation Satellite Systems (GNSS). The dynamic development of GNSS has contributed to the fact that current users are able to use four global systems that use more than 120 satellites. This progress was related not only to the space segment but also to the user segment. Modern technology and miniaturization have resulted in the users' disposal of different types of GNSS receivers, including geodetic receivers, gaining popularity low-cost receivers, or other devices using the GNSS signal, such as smartphones, sports trackers, or sports watches.

Modern sports watches are equipped with many sensors, among which GNSS chipsets play an important role. Those GNSS chipsets make it possible to determine the distance traveled and other related parameters that are important from the point of view of athletes. The most modern constructions can track several constellations at the same time. However, it is difficult to find reliable information to determine the actual quality of positioning by these low-cost GNSS receivers. Most of the works use comparative methods of watches and visual analysis of the route covered. Due to the above-mentioned gap in this area, the positioning quality of leading manufacturers of sports watches was assessed in this study.

Ten sports watches from Garmin, Polar, and Suunto were assessed in the study regarding the geodetic grade GNSS Trimble receiver. The watches were evaluated in three experiments: field positioning experiment, distance accuracy experiment conducted on the athletics track, and the accuracy of the altitude determination conducted on the 37 m high tower. The tests were performed for all the GNSS system options available in watches. The best positioning quality was obtained for the Polar M430 watch that uses only GPS for which almost all recorded epochs obtain positioning accuracy better than 5 m. When measuring distance, most watches had a result that was less than 1% from the theoretical value. Garmin Vivoactive 4s achieved the best results in height determination. For 11 different measured levels, located about 3 m apart, it obtained an average difference equal to 0.48 m. The results show also that the use of the additional GNSS system degrades the obtained results in some cases.