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The accuracy of the results of satellite measurements is influenced by many factors. One of them is the multipath phenomenon resulting from reflections of the satellite signal, mainly from objects in the vicinity of the GNSS antenna. The multipath remains a domain source of ranging errors in satellite positioning. Despite the groups of multipath mitigation methods, it is impossible to totally eliminate the influence of this error on the measurement results. This error has two main effects in the case of carrier phase differential positioning. First, the multipath increases the initial search space for correct ambiguities. Secondly, the accuracy of the vector solution between the reference station and the rover receiver is affected. The authors of this article analyzed the presence of multipath in the Polish network of permanent GNSS stations ASG-EUPOS. Data from the year 2021 were used for the analysis. Two computational strategies were adopted to determine the multipath. The pseudorange multipath observable combination (MP) for L1, L2 and L5 signals was used for code measurements. In the case of the carrier phase, multipath analyses of double-differenced L1, L2, and L5 carriers between neighbouring stations were performed. Based on the research, the average multipath level for the Polish GNSS reference stations network was determined. Stations where the levels of particular combinations exceed the assumed values were successively determined. Finally, multipath models in the form of sidereal maps were created. Based on these models, six stations were identified and recommended for further analysis concerning the impact of multipath on GNSS measurements. [ABSTRACT FROM AUTHOR]

The study introduces the concept of regional GPS orbit determination, whereby GPS satellite positions are determined using GPS measurements from locally or regional distributed stations. The importance and characteristics of regional GPS orbit are briefly discussed. The technique used to determine the regional GPS satellite position is coined Inverse Single Point Positioning (ISPP). Code-based pseudorange is used and improved using residual correction model. Two designs of station distribution are selected in this study, which only cover stations in Malaysia and stations situated 8000 km from a reference point in Malaysia. The root-mean-squared-error (RMSE) of ISPP when compared against final ephemeris were 660.65 m and 27.61 m, while the 3D RMSE of positioning were 1.612 m and 1.324 m for the first and second designs, respectively, lower than the accuracy of broadcast ephemeris. Three parameters are identified as factors affecting accuracy of ISPP, namely geometry of station distribution, nature of measurement used, and technique of orbit determination. Further research will be required to fully realize a functional regional GPS orbit. [ABSTRACT FROM AUTHOR]

In recent years, there has been a drastic increase in navigation satellites. Due to the computational limitations of a global navigation satellite system (GNSS) receiver, such as limited tracking channels, bandwidth, and high-power consumption, selecting an optimal subset of satellites with a better geometric dilution of precision (GDOP) has become increasingly difficult. Moreover, the computation load on the receiver increases with multi-channel observation. However, a reduced subset of used satellites will significantly increase the receiver computation performance without compromising the positioning accuracy. This paper presents an end-to-end neural network (NN) architecture based on PointNet and VoxelNet to provide an optimal satellite subset from a multi-constellation with a minimum GDOP. The architecture is based on per-satellite parameters obtained from the global positioning system (GPS) and navigation with the Indian Constellation (NavIC) satellites. Experimental results indicate that the input channel with satellite positions, Doppler, acquisition peak metric, elevation, and azimuth angles provides the best outcome in terms of performance. This method can reduce the computation burden and time by 40–50% when used in the receiver. [ABSTRACT FROM AUTHOR]

For users of Precise Point Positioning (PPP), Multi-GNSS Advanced Orbit and Clock Augmentation PPP signals provide corrective data. When using the PPP approach and/or PPP-Ambiguity Resolution (AR) method, the QZSS signal provides globally applicable error corrections on satellite orbit, clock offset, and code/phase biases. In addition, from FY2024, as a part of the MADOCA-PPP technology demonstration, wide-area ionospheric correction data will be provided for the Asia-Oceania region. A software estimator of precise satellite information developed by JAXA, Multi-GNSS Advanced Demonstration Tool for Orbit and Clock Analysis (MADOCA), allows u-blox CO99-ZED-F9P and MSJ 3008-GM4-QZS utilizing MADOCA-PPP to be used in GNSS applications that need sub-decimetre precision but don't have to be expensive. Errors caused by positioning satellites are computed by using observation data from domestic and overseas GNSS monitoring station networks such as IGS and MIRAI, and obtained correction data is transmitted from QZSS signal to provide highly precise positioning augmentation services that can be used in the Asia-Oceania Region. Users may utilize the PPP technique for high-precision locating by employing a GNSS receiver that supports the QZSS signals. This paper describes an experiment carried out with the static method to combine GPS, GLONASS, and QZSS signals in the project site (ISHI, USUD and MIZU stations in Japan). This paper examines the GPS/GLONASS/QZSS obtainable accuracy. These obtained results indicate that integrating GPS system with GLONASS and QZSS is favoured for surveying applications. It appears that integrating GPS/GLONASS/QZSS (MADOCA precise ephemeris file) static measurements in the study area between 0-4 millimetres accuracy can be guaranteed on all occasions. [ABSTRACT FROM AUTHOR]

The paper presents the analysis of single-point GPS positioning results obtained from smartphones, using code observations on the L1 and L5 frequencies. In this research we used two Huawei P30 Pro mobile phones and one geodetic receiver (Javad Alpha) acting as the reference receiver. Smartphones were placed at an equal distance of 0.5 m from this receiver. Such a close distance was specially planned by the authors in order to achieve identical observation conditions. Thus, it was possible to compare the accuracy of GPS positioning using pseudoranges on the L1 and L5 frequencies for individual observation epochs. The analysis was carried out from static GPS positioning, using the results from the open-source RTKLib software. In general, the usefulness of code measurements on the L5 frequency to determine the GPS position made it possible to increase the accuracy by several times with respect to the positions determined using the C/A code on the L1 frequency. Average errors of horizontal and vertical coordinates were about 70 % lower for the GPS solution using the L5 code observations than using the L1 code observations. Based on statistical analysis, a horizontal accuracy of about 0.45 m and vertical accuracy of about 1.8 m (STDEV) with only five GPS satellites may be obtained using a smartphone with L5 code observations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sports watches provide coordinates in the WGS84 reference system. • The majority of sports watches can track only two GNSS systems simultaneously. • The positioning accuracy is not always better for multi-GNSS watches. • The accuracy in sports watches for 2D positions is robust at the few-meter level. • The accuracy of height measurements in sports watches is low and unstable in some cases. Sports watches come equipped with Global Navigation Satellite System (GNSS) receivers capable of tracking GPS, GLONASS, and Galileo, and thus, can be considered low-cost GNSS receivers. In our research, we conducted three distinct experiments to evaluate the accuracy of 1) positioning, 2) distance determination, and 3) height determination based on sports watches using different GNSS combinations: GPS, GPS + GLONASS, and GPS + Galileo. For positioning, a professional GNSS receiver served as the reference. To determine height, we used a laser rangefinder. The assessment of distance measurement utilized a full-size athletics track. A noteworthy outcome of this study is that the increased cost of sports watches does not consistently correlate with higher GNSS positioning accuracy. The most accurate 2D results are achieved by the Polar M430 for the GPS case with the mean positioning error of 1.74 m, and the Garmin Fenix 6 PRO for GPS + GLONASS case with the mean error of 1.43 m. [ABSTRACT FROM AUTHOR]