Positioning accuracy:
In order to validate the positioning accuracy of the Pozyx Creator system, extensive tests have been performed using mm-accurate ground truth data. The tests were performed within an office space of 7m x 9m with a person holding the tag upwards in his hand and moving around. For this test, four anchors were used, placed at the edges of the area at roughly 2m height. Test were made using ultra-wideband channel 5, preamble length 1024, prf 64MHz, and bitrate 110kbps. Similar results can be expected on different channels with different bitrates or prf. Shorter preamble lengths may slightly reduce the accuracy. One test was performed in an open area with no obstacles, i.e. the line-of-sight (LOS) test. A second test was performed with two anchors consistently blocked with metal racks filled with bottles of water, this is the non-line-of-sight (NLOS) test. Two algorithms available on the Pozyx tag were compared: the UWB_ONLY algorithm and the TRACKING algorithm, both for 3D positioning. In the figure below, the cumulative distribution function of the horizontal (xy) positioning error is shown in millimeter for both algorithms.

Fig. Experimentally measured positioning error (in xy-plane).
From this figure, it can be seen that both algorithms perform similarly. For both algorithms, the average horizontal error in LOS is 92mm and 140mm in NLOS. The average vertical error was typically larger which is expected as a result of the poor anchor placement (all in the same plane at only 2m height). In the figures below, a scatter plot of this test is shown for each algorithm.

Fig. experimentally measured positioning trajectory using the TRACKING algorithm.

Fig. experimentally measured positioning trajectory using the UWB_ONLY algorithm.
Although both algorithms perform similarly on average, it can be seen that, in general, the TRACKING algorithm provides a much smoother trajectory, whereas the UWB_ONLY algorithm provides more jittery results. This is because the TRACKING algorithm uses previous position estimates in its estimation which smooths the result. It is suggested to use the TRACKING algorithm when performing continuous positioning. In scenarios where the position is only obtained once, or at very low update rates (multiple seconds or minutes), it is suggested to use the UWB_ONLY algorithm.
Note that the accuracy may be lower outside the area covered by the anchors. Furthermore, the best performance is obtained with the antennas in an upright position. For a better accuracy in the vertical direction it is suggested to place the anchors at different heights, sufficiently higher and lower than the height of the tag. This reduces the geometric dilution of precision (GDOP) as much as possible.