# Designation of the Quality of EGNOS+SDCM Satellite Positioning in the Approach to Landing Procedure
## 4 Results  
Section 4 presents the results of the conducted research. Firstly, the results of the measurement weights determined with use of Equation (2) are presented. The values of measurement weights obtained from a single SDCM ranged from 0.125 to 0.2, while those from EGNOS solution ranged from 0.111 to 0.166. To analyse the results presented in Figure 5, it is worth referring to the results shown in Figure 3, i.e., to the number of GPS satellites with SDCM and EGNOS corrections. One may say that, as the measurement weight increases, the number of GPS satellites use in the EGNOS or SDCM solutions decreases. This correlation is also true for the reverse direction, so that, as the number of GPS satellites tracked by the receiver increases, the measurement weight decreases, as it is described in Equation (2). It should also be noted that the relation described by the mathematical Equation (2) changes exponentially. Then, Figure 6 illustrates the obtained values of standard deviation calculated with use of Equation (3). The values of the \((\delta B,\ \delta L,\ \delta h)\) parameters are determined for the resultant coordinates of the aerial vehicle in the Multi-SBAS solution. The maximum values of the \((\delta B,\ \delta L,\ \delta h)\) parameters are, respectively: for component B up to 0.25 m, for component L up to 0.22 m, and for component h up to 0.62 m. The analysis of the results presented in Figure 6 reveals that the highest values of standard deviation were obtained for the vertical component h. Moreover, the standard deviations of \(\delta B\) were approximately 60% lower than values of \(\delta h\) results. On the other hand, the standard deviations of \(\delta L\) were approximately 65% lower than those of the \(\delta h\) parameter. Figure 7 shows the results of Multi-SBAS positioning accuracy for the position of the aerial vehicle. The obtained values of the accuracy of positioning with use of multi-system SBAS solutions were obtained from Equation (4). These results were expressed in form of ellipsoidal coordinates BLh. Obviously, it should be noted that in order to determine the positioning accuracy, the resultant coordinates of the aerial vehicle obtained from the Multi-SBAS solution were compared with the reference position of the flight calculated with use of the RTK-OTF differential technique. The accuracy of the determination of the geodetic latitude B from the Multi-SBAS solution during the landing approach procedure ranged from \(-\)1.58 m to +0.33 m, whereas the mean accuracy for the geodetic latitude component B equalled \(-\)0.65 m. On the other hand, for the geodetic longitude L, the positioning accuracy ranged from \(-\)1.62 m to +0.40 m, with a mean value of \(-\)0.50 m. The accuracy of positioning the vertical component h from the Multi-SBAS solution ranged from +0.45 m to +3.38 m. The mean value of positioning accuracy along the h axis equalled +2.18 m. The comparison of the resulting values of the \((dB,\ dL,\ dh)\) parameters revealed that the accuracy values \(dB\) were approximately 70% lower than the obtained results of \(dh\) position errors. Additionally, the values of accuracy of \(dL\) were 77% lower than the \(dh\) position errors. Important parameters that must be determined in the accuracy analysis are the RMS errors. The values of these errors were calculated from the formulas provided in Equation (5). Based on the conducted research, it was determined that the lowest values of the RMS error were obtained along the L axis, and the highest one for the vertical component h. The values of the obtained RMS errors are presented in Table 2.  
Figure 5: The values of measurement weights from each SBAS solution. Figure 6: The values of standard deviations for resultant position of aircraft. Figure 7: The values of position errors. Additionally, the vector of coordinate shift \(dr\) on a 3D plane was determined for the accuracy parameter, according to Equation (6).