# GNSS Multipath Detection Using Continuous Time-Series C/N0
## 5 Discussion  
In this section, the results of the three tests are summarized and briefly discussed. Figure 22 presents a comparison of the RMS errors in the horizontal direction in the three locations for the DGNSS. Figure 23 compares the correct fix rates in the three locations for the RTK-GNSS. The approximate distances between the buildings on either side of the road in the three locations were 43, 41, and 12 m in the order of the experiments. As shown in these two figures, our new multipath detection method was very effective in improving the DGNSS as well as the RTK-GNSS. As depicted in Figure 10, the residuals of the satellites in the least-squares method were checked. If the absolute residual of the satellite was the maximum and was over 10 m, the satellite was repeatedly removed from the positioning. Without this step, the performance of the normal DGNSS was substantially worse than the results shown in Figures 14 and 17 in the case of the relatively long distance between the buildings on either side. In reality, the maximum number of residual checks in a single epoch was 8 in both locations 1 and 2. Errors over 50 m continued for a long time without the residual check step. In this sense, the residual check in the least-squares method was effective in challenging environments surrounded by many high-rise buildings. However, a limitation existed in removing satellites with large pseudo-range errors because large errors still remained, and the method was not effective in the third location because the errors owing to the NLOS signals were not large. For the case of the new approach in the three different locations, the number of residual checks in a single epoch was almost 0. As the large errors were mostly reduced following the proposed time-series C/N\({}_{0}\) check, the residual check was not as necessary. Even if satellites with large errors remained after using the new approach, it was easy to detect the satellites because the residual check works very effectively if only one or two satellites exhibit large errors. According to the RTK-GNSS results in Figure 23, the correct fix rate was significantly improved at all locations. This is because the RTK-GNSS requires the accuracy of the absolute position based on the pseudo-ranges to be within several meters. If the absolute position deviates by over 10 m, it is impossible to resolve correct ambiguities. Figure 21: DGNSS horizontal errors using new method. Figure 24 compares the RMS errors in the horizontal direction in the three locations for the DGNSS using the new method. The results using three different periods were also compared. As discussed in Section 3, we had to set the periods during which the satellite was not used for positioning after the C/N\({}_{0}\) decreased below the threshold. The lengths of the period were set to 180, 240, and 300 s. As can be observed from Figure 24, the difference among the three periods was not substantial. We assert that a longer period will be required to remove the satellite properly in the case of a short delay of the multipath to the direct path. As illustrated in the case of 12 m between the buildings on each side, a longer period enables the accuracy of the DGNSS to be improved. Figure 25 compares the RMS errors in the horizontal direction at the three locations for the DGNSS using the new method. The results using five different thresholds were also compared. The period was set 240 s. As discussed in Section 3, we had to set the threshold to detect which satellite was not used for positioning. Five thresholds were set 6, 8, 10, 12, and 14 dB-Hz, respectively. As can be observed from Figure 25, RMS errors in all cases were less than the normal DGNSS. Although the best threshold cannot be decided by using these results alone, it seems to be that the favorable range of the threshold was from 8 to 1 dB-Hz. In the case of 12 m between the buildings on each side, the strict threshold setting was allowed.