Elevation mask and type of receiver effects on points positioning accuracy

The main goal of our research was to investigate the influence of the elevation mask, vectors length, GNSS receivers type (single or dual frequency), and observation duration on positioning accuracy in satellite geodetic networks using only GPS and both GPS/GLONASS signals. Methods. As the initial information the results of 10 days GNSS observation from 35 permanent stations in France (www.rgp.ing.fr) was taken. These results of observation were used for design three networks: first two contained 12 stations, and third – 11. An average distance between stations varies from 21,9 km to 24,1 km. The satellite observation processing was carried out by Trimble Business Center with changing such parameters as: observation duration – 24, 12, 6, 3, 2, 1, 0,5 and 0,25 hrs; elevation mask – 0º, 5º, 10º, 15º, 20º, 30º and 40º; GNSS receiver types (single or dual frequency). Beside that every network was processed for only GPS signals and for both GPS and GLONASS signals. The total amount of such sessions was 12096. The comparison of real coordinates of stations with the coordinates of the same stations, resulting from such adjustments, allows us to compute RMS of the positioning for such different adjustment conditions. Results. The RMS analysis revealed the lowest positioning accuracy for single- and dual-frequency receivers for sessions lasting from 0,25 to 12 hours and elevation angle 40º. The best results should expect for elevation mask 20–30º and sessions duration from 1 to 12 hours. Observing two systems satellites (GPS i GLONASS) for single- and dual-frequency receivers the best results achieved sessions duration from 1 to 12 hours and elevation angle 30º, while the worst accuracy achieved for elevation mask from 0º to 15º, and also for sessions duration less than 1 hour using an elevation mask angle of 40°. For the session durations of 0,5 – 0,25 h. the highest positioning accuracy is for elevation mask of 15–20° (for dual-frequency receivers). Additionally the investigations showed that for dual-frequency receivers with sessions duration from 3 to 24 hours there is no difference which signals are observed GPS or both GPS and GLONASS. Scientific novelty and practical significance. The studies of efficient elevation mask increasing with the presence of a larger number of GNSS-satellites and large amount of satellite observations makes obtained results more reliable, compared to the results obtained by other researchers. The result allows adopting the optimal mask angle in the establishing of satellite geodetic networks with use of single- and dual-frequency receivers, when observing GPS system only and when combined GPS/GLONASS observations.