| Popis: |
GNSS observations are carried out in static mode/ Differential global navigation satellite system (DGNSS) and dynamic mode / Real time Kinematics (RTK) mainly. RTK mode of observation is useful in case of navigation whereas in order to determine very precise positioning, static / DGNSS/ DGPS mode is recommended. In this study, we have examined the quality of DGNSS survey of an urban city in India over ~300 Ground Control Points. Survey is carried out in DGNSS mode with dual frequency mode. All the observations were recorded using GPS, GLONASS , Galileo and Beidu with GDOP values in the range of 1.4 to 2.5. Beidu was used in broadcast ephemeris mode whereas for other constellations, precise orbit ephemeris were obtained from International GNSS service (IGS) site as per the observation day and month. Further, all the data was post processed in the SW suite and positional and vertical accuracies of millimeter to few centimeter level were obtained. This paper describes the approach of Ground Control Point (GCP) identification, surveying, methodology, use of CORS network and data post-processing in order to achieve such a precise accuracies in the urban city. |
