Network-RTK - A comparative study of service providers currently active in Sweden

Sammanfattning: Network-RTK is a method of relative measuring using GNSS that provides users in alarge area with an easy way obtaining low uncertainties in their measurements. Regularnetwork-RTK does not meet the requirements of the Swedish Transport Administration(STA) regarding its larger and/or more complex projects, leading to the concept ofproject-based network-RTK being introduced in Sweden by the STA, in collaborationwith the network-RTK service provider SWEPOS back in 2004. This concept improvesupon regular network-RTK by decreasing the uncertainties and increasing reliabilitieswithin the project area. SWEPOS has since the collaboration back in 2004 supplied theSTA with project-based network-RTK services.The market is not the same today as it was in 2004 and there are more service providersactive in Sweden. This thesis intends to find out if this new market means that there areother alternatives to SWEPOS with regards to the STA’s requirements for project-basednetwork-RTK. This is done through a technical comparison of the different serviceprovider’s measurement uncertainties and their measurement accuracies as well as acomparison of their surrounding infrastructure and the subjective user experience.Similar studies have been conducted before (Edwards et al., 2010) (Martin andMacGovern, 2012) (Saeidi, 2012), but never in Sweden nor with SWEPOS as one of theservice providers as it is only available in Sweden. Neither have they had a focus onmeasurement uncertainties and accuracies in a project-based network-RTK net. Theyhave all concluded that there were no significant differences between any of the serviceproviders compared, in both the measurement uncertainties and accuracies.For the technical part of this thesis, measurements were conducted at four sites: two atdifferent locations within the area of a former, STA project-site, one within the regularnet and the final site outside the entire net, with the amount of collected data varying forthe different sites. Five different GNSS receivers of different brands were used for themeasurements to make it as general as possible.The results show that there are slight differences in the height uncertainty, but the scopeof this thesis does not permit the full correlation study needed to determine if thesedifferences are significant. There does not seem to be any differences in the accuracies ofthe service provider. Some of the sites with less data collected show contradictoryevidence to this statement, but it is deemed that these deviations are more likely relatedto something other than the service providers, such as human interference or errors.Large differences exist in the user experience and surrounding infrastructure, an areawhere SWEPOS at the moment has a clear lead. This is believed to be due to SWEPOSprimarily being a network-RTK service provider and thus allocating more resources andpersonnel, whilst the other service providers also serve as equipment vendor andmaintainers.Combining the two comparison parts leads to the overall conclusion that with theservice providers in their current state with the requirements of the STA specified intheir current state, only SWEPOS is a viable alternative as a supplier of project-basednetwork-RTK. But this is something that could change with relative ease depending on ifthe other service providers allocate more resources.