## 6 Conclusions  
Dual-frequency smartphones and geodetic GNSS receivers were analyzed in different jamming conditions. The objectives of this study were to analyze the differences between the geodetic receivers and double-frequency smartphones on the quality of observations under severe interference and to evaluate the positioning performance of all the devices in difficult conditions for positioning. The first objective was to understand the main factors affecting the signal reception of smartphones under jamming conditions and to compare their responses with those of professional geodetic receivers. However, the main objective was to show the usefulness of smartphones in localizing jammers. Using the algorithm and the response of smartphones placed statically along the road, the localization of the jammer was tested for different devices. In addition, an analysis of the relative carrier-phase positioning for the smartphones and geodetic receivers was performed to gain insight into their robustness in accurately determining position during chirp jamming events. The results from this study led us to the following conclusions:  
* Carrier-phase smartphones continued receiving data even in high interference scenarios when the geodetic receivers failed. * The quality of positioning under jamming conditions deteriorated a great deal for the smartphones. * Various jammers have different effect on the signals from different constellations. * There is a significant discrepancy between the results obtained using RTKLIB and Leica Infinity software when the results are inconsistent with the real position. It can be concluded that smartphones have an advantage over professional geodetic receivers in jamming localization because they can receive signals from satellites even under jamming conditions; in such cases, geodetic receivers cancel the measurements to avoid incorrect positioning. However, it is important to remember that there is a lot of mispositioning in such cases and that only the CNR values of the GNSS receivers should be relevant for locating the interfering transmitter. Since the current study verified the localization of jammers using smartphones placed statically at the roadside, we are left with a major challenge for the future, which is to localize a jammer using devices operating in kinematic mode. Another important future evolution of this study may include the use and testing of hardware and software filters on professional GNSS receivers to mitigate interference effects, increase CNR values, and analyze the effects on positioning accuracy. Furthermore, the methods used in this study could be a starting point for an automated jammer-localization algorithm. This could be achieved in real time without any postprocessing software, since the CNR measurements can be obtained by other means, for instance, by inspecting the corresponding NMEA sentences (GSV in particular) that all the GNSS chipsets are able to provide. **Author Contributions:** Conceptualization, P.P.-P., M.B. and F.D. ; method, P.P.-P., M.B. and F.D. ; software and validation P.P.-P. and M.B. ; formal analysis, P.P.-P. and M.B. ; field tests: P.P.-P. and M.B; writing--original draft preparation, P.P.-P., F.D. and M.B. ; writing--review and editing, P.P.-P., M.B. and F.D. ; visualization, M.B. and P.P.-P.; project administration, P.P.-P. and F.D. All authors have read and agreed to the published version of the manuscript. **Funding:** The authors acknowledge the financial support of the Slovenian Research Agency (research core funding No. P2-0227 Geoinformation Infrastructure and Sustainable Spatial Development of Slovenia, and No. P2-0394, Modelling and Simulations in Traffic and Maritime Engineering). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.