The Impact of Ionospheric Variations on GNSS Measurement Accuracy : “A comparison of Rapid and Detailed Point Measurement under different Ionospheric conditions”

The ionosphere is a significant source of error when it comes to GNSS measurement. This is especially true during the periods of high solar activity such as the anticipated solar maximum. The solar maximum is said to be taking place during the years of 2024 and 2025. Since this study is made during 2025 the purpose is to see how much this affects the measurements. More specifically this study investigates how much the different ionospheric variations impact on the accuracy of NRTK measurements, and this is made by using two common methods such as rapid measurement (1 second) and detailed measurement (60 seconds). These methods will be compared to each other to see if there are any differences in measurements uncertainty, and to see if it’s possible reaching the goals from HMK:s standard for positional uncertainty (standardosäkerhet). These measurements will be taking place during different ionospheric conditions (green, yellow and red zones) using SWEPOS ionosphere monitor. For these measurements a reference point was established using double-set observations to ensure high precision. Data was collected over two days during both daytime and nighttime to ensure that all necessary data were collected from all various ionospheric zones. Measurements over the reference point was made using Trimble R10-2 receiver connected to SWEPOS NRTK. The study found that both rapid and detailed point measurements achieved acceptable accuracy in Northing and Easting coordinates across all ionospheric conditions. However, a systematic height discrepancy of 18 - 19 cm was observed. This was likely due to the reference network errors, rather than disturbances connected to the ionosphere. The decision was made to compare all heights to the mean height for all measurements, instead of the height from the reference point. As a result, to these changes the mean height difference was reduced to 8 millimeters. Analyses conducted using ANOVA showed no significant difference between the two measurement methods in any of the various zones. In terms of reaching the criteria of the HMK´s requirements for NRTK, both methods fulfilled the criteria for gross errors and positional uncertainty in the horizontal plane. The findings suggest that if correct equipment and methodology is used, measurements can achieve acceptable results that are reliable. For future studies extended observation time could be used and using a single setup for all measurements.