## 3 Results
### Different Signal Reception
Older smartphones (Samsung S5 and Huawei P20) used on average 9.2 or 9.6 active satellites, while modern smartphones (Xiaomi Mi 10 light and Huawei P40) used up to 25.8 or 29.4 satellites for positioning at the same time in the experiment. If one also considers the frequency bands, the number increases to 40.0 and 48.8 bands, respectively. This means that a much higher potential was exploited, and more information was used to determine the position. Even smartphones that were identical or almost identical in construction differed from each other. However, the two identical single-frequency Xcover 4s smartphones showed very slight, non-significant differences. On the other hand, the Xiaomi MI 8 and Xiaomi MI 8 Pro, which were equipped with the same GNSS chip, differed significantly from each other in some cases. This is particularly evident when using the E5a frequency, of which the Xiaomi MI 8 Pro used the 1.7 (56%) band and the Xiaomi MI 8 the 3.5 (92%) band. The Xiaomi MI 8 used an average of 19 frequency bands to determine its position, whereas the Xiaomi MI 8 Pro used only 14.6 frequency bands under the same recording conditions. This significant difference cannot be explained without a deeper analysis of the hardware and software. A more detailed representation of the satellites in use and their proportions can be seen in Figure 5. It shows the relative frequency in relation to the satellites in use (not the frequency bands of the received positions). The relative frequency of the distribution of the satellites for the smartphones is highly diversified. In Figure 5, blue indicates smartphones with multi-frequency capabilities, and red indicates smartphones that can only receive the L1/G1/E1/B1c bands. The recorded time periods, the time stamps, and the recording conditions are identical for all smartphones. It is evident that the new models,such as the Huawei P40 and the Xiaomi Mi 10 light, use significantly more satellites for positioning, with the former having more than 20 satellites in use over almost the entire study period. This is more than the maximum number for most other smartphones. One explanation for this is the improved hardware, which brings about improved performance with new generations of smartphones and thus a higher number of satellites that can be used. Figure 5(a) clarifies this relationship using the satellites in use, which were measured in this study in relation to their release dates. In particular, the newer models from 2020 show very high values. This is mainly due to the consistent simultaneous use of all four available constellations. If the different frequency bands are added, this difference becomes even more apparent (Figure 5(b)). It is noticeable in Figure 5 that the Xiaomi Mi 8 and the Xiaomi Mi 8 pro both have two-peaked distributions. Both smartphones had partial initialisation problems below the canopy and provided no or only limited position data over more extended periods during the measurements. This was mainly a result of the different canopy cover. If the overshadowing were stronger, then the NAVSTAR GPS would dominate in terms of position detection and Galileo. BeiDou satellites are hardly used anymore, resulting in a number of satellites in use, which are similar to those used by the older models. The Xiaomi Mi 8 pro uses either between 5 and 12 satellites or between 18 and 23 satellites, and the values in between are almost non-existent. The Xiaomi Mi 8, in particular, often had problems with positioning under the canopy, which only provided positions on average around 77% of the time to the other smartphones under the canopy (see Table 4). In the satellite distribution of the Huawei P 20, a phenomenon occurs that significantly lowers every uneven satellite value. This cannot be explained technically and will undoubtedly affect the smartphone's evaluation software. In Figure 7, the skyplots illustrate the mean carrier-to-noise-density ratio C/N\({}_{0}\) of satellites in use for the different smartphones as a function of azimuth and elevation.