Tracking Performance in Endurance Racing Sports: Evaluation of the Accuracy Offered by Three Commercial GNSS Receivers Aimed at the Sports Market

Gløersen Ø., Kocbach J., Gilgien M.

Objective:
The study aimed to assess the accuracy and applicability of three commercially available global navigation satellite system (GNSS) receivers targeted for sports use in analyzing time performance during endurance racing sports, particularly cross-country skiing.

Methods:

The evaluated GNSS receivers included a 1 Hz wrist-worn standalone receiver (Garmin Forerunner 920XT, Gar-920XT), a 10 Hz standalone receiver (Catapult Optimeye S5, Cat-S5), and a 10 Hz differential receiver (ZXY-Go).
Validation was conducted against a geodetic, multi-frequency receiver providing differential position solutions with accuracy < 5 cm. Six volunteers skied four laps on a 3.05 km cross-country skiing track, with all four GNSS receivers measuring simultaneously. Deviations in position (horizontal plane, vertical, direction of travel) and speed (horizontal plane and direction of travel) were calculated. Time analysis was performed for all possible pairs of laps, calculating the time difference between any two skiers for each integer meter along the track. Results: Horizontal plane position errors were 2.09 m (Q3), 1.04 m (Q3), and 5.29 m (Q3) for ZXY-Go, Cat-S5, and Gar-920XT, respectively. Vertical precision was 2.71 m (IQR), 3.89 m (IQR), and 13.35 m (IQR) for ZXY-Go, Cat-S5, and Gar-920XT, respectively. Precision in horizontal plane speed was 0.038 m/s (IQR), 0.072 m/s (IQR), and 0.66 m/s (IQR) for ZXY-Go, Cat-S5, and Gar-920XT, respectively. Time analysis precision was 0.30 s (IQR), 0.13 s (IQR), and 0.68 s (IQR) for ZXY-Go, Cat-S5, and Gar-920XT, respectively. Error was inversely related to skiing speed, with larger errors occurring at lower speeds. Conclusion: The study found that the differential (ZXY-Go) and 10 Hz standalone (Cat-S5) receivers outperformed the wrist-worn receiver (Gar-920XT) in terms of horizontal position and speed calculations. All receivers provided sub-second accuracy in time analysis, except at very low skiing speeds.

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