**3. UWB in scientific articles**

Based on a recently published systematic review about the validity and reliability of LPS technology [9], and additional one added due to its recently publication [16], it may be summarized that three studies used UWB technology with 6 antennae around the field and, in general, 18 Hz [10, 17–19], and one used UWB technology with 8 anchors and 33 Hz [16]. All of them belong to three different manufacturer: Realtrack Systems [10, 17, 18], KINEXON [20], and Ubisense [19].

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*Review of Ultra-Wide Band in Team Sports DOI: http://dx.doi.org/10.5772/intechopen.94591*

Realtrack Sytems´ UWB (WIMU PRO™, RealTrack Systems, Almeria, Spain) was tested in indoor context to assess its validity, revealing 5.2 cm (0.97%) and 5.8 cm (94%) of mean absolute error (MAE) of all estimations in x- and y- position, respectively [17] (**Table 3**). The same system, in outdoor field showed a MAE of 9.57 cm in x-axis positioning and 7.15 cm in y-axis positioning [18] (**Table 3**). A third study assess the validity of an UWB during linear, circular and zig-zag drills in soccer training in walking and running intensities [10]. The authors showed a bias (%) of 0.55 to 5.85% for determining distance covered, and, moreover, a bias between −0.56 and 0.67 for determining mean velocity [10]. Additionally, this system has been compared with an GNSS revealing lower MAE than satellitebased system (**Table 3**). Athlete tracking technology is continually improving due to developments in microprocessors, data processing, and software [21]. Hence, Realtrack System have provide a new modified UWB with height antennae and 33 Hz, which has been recently compared against a real-measure [16]. The authors showed that the mean difference (MD) was less than 4 cm and in 95% of the cases was between 1 cm and 7 cm. the magnitude of the differences was expressed as 0.28% with real measures as the reference. %CV was less than 1% in all cases (**Table 3**). Despite the fact that Realtrack System (Almería, Spain) has published most of the article, an alternative brand of UWB (Ubisens Series 7000 compact tag) was also tested for its accuracy [19]. The authors also showed sufficient accuracy to test positions of players independently of the length of the recorded runs (**Table 5**). Summarizing, all manufacturers that provide UWB technology have showed acceptable accuracy levels for monitoring the position of players in team

Four studies [16–18, 20] aimed to assess the reliability of LPS based on UWB technology. Hoppe et al., (2018) assessed the reliability calculating the differences between the KINEXON ONE UWB devices of each positioning system (i.e. the between device reliability) though typical error. They found typical errors between 0.1 (criterion variable of 10 m jogging with jump) and 1.7 (criterion variable of 129.6 m entire circuit). The LPS revealed good reliability for the entire distance covered, walking over 10 m and sprinting with change of direction, sprinting over 30-m, sprinting over 5–20 m and theoretical maximal force and horizontal power [20]. In addition, Hoppe et al., [20] compared the results of GPS and UWB, and despite some contradictorily results, comparisons of reliability between the GPS

Regarding to the other commercial UWB based device from RealTrack Systems was tested for its intra- and inter-unit reliability [17]. These tests assisted with understanding the degree of error and the amount of variation between the units. A Mann– Whitney U test was performed to compare differences in the differently designed routes and between devices (i.e. the variation in data measured in one participant or another). Inter-unit reliability (i.e. the difference in using one device or another) was determined using Hopkins's reliability spreadsheet to calculate the percentage typical error of measurement and the intra-class correlation coefficient (ICC) values. The intra-unit reliability of UWB in mean velocity varied between 0.895 and 0.999 of ICC (95% of confidence interval) and the low and upper (for inter-unit variability) ranged between −0.09 and 0.42%. In the case of distance covered, the typical error of UWB varied between 0.94 and 4.87% and the lower and upper bias was between

**3.1 Validity of UWB technology**

sports settings (**Tables 3–5**).

**3.2 Reliability of UWB technology**

and LPS was mainly favorable to LPS [20].
