Determining and improving the accuracy of orthometric and geodetic height with the NRTK system. case study of the Shamim system

fattaholmanan, ali; jazireiyan, iraj; asgari, jamal

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Volume 14, Issue 4 (6-2025)

JGST 2025, 14(4): 51-58

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Determining and improving the accuracy of orthometric and geodetic height with the NRTK system. case study of the Shamim system

Ali Fattaholmanan ^*

, Iraj Jazireiyan

, Jamal Asgari

Abstract: (330 Views)

In recent years, the use of real-time kinematic positioning networks has received much attention due to its advantages. The high accuracy and speed of positioning are the greatest advantages of these networks, so the use of observations in NRTK systems in study and implementation projects to determine the height component of points that are traditionally time-consuming and expensive is considered. In this article, the practical aspects of height determination by real-time positioning in the NRTK system have been examined. In the first part of the article, the aim is to investigate and determine the optimal time for conducting observations using the NRTK method and using the moving averaging technique to achieve the highest accuracy for the geodetic height of points. For this purpose, observations were made for 4 stations located in Isfahan city and were repeated for 20 minutes at a time rate of one second. Static observations of the stations were also carried out in order to extract their precise coordinates. In the second part, due to the availability of the geoid of Isfahan city, the accuracy of orthometric height obtained from instantaneous positioning in the NRTK system was evaluated. 33 benchmarks in the city of Isfahan, whose accurate alignment data were also available, were observed in the NRTK system to perform this evaluation. In the first part of the results, by calculating the RMSE of observations for each station, it was determined that the accuracy of observations increases with time. Based on the results of the calculations, it was determined that the accuracy of observations has the highest accuracy after 15 minutes from the start. From the start of receiving corrections until this time, the accuracy of observations has been increasing, and after that, the process of increasing accuracy almost stops. Therefore, by using the moving averaging technique for observations in the fifteenth minute time interval, an observation with higher accuracy can be achieved. By applying this technique, observations with lower accuracy are excluded from the calculations, so the final accuracy of observing the geodetic height of the desired point increases. In the second part of the results, by calculating the average RMSE of the benchmark observations, the final accuracy of determining orthometric height using the NRTK method in the study area was 0.0281 m. Achieving this accuracy in determining orthometric height of points makes it possible to avoid costly and time-consuming traditional leveling operations in many projects.

Article number: 4

Keywords: NRTK, RMSE, geodetic height, orthometric height, local geoid

Full-Text [PDF 790 kb] (145 Downloads)

Type of Study: Research | Subject: Geo&Hydro
Received: 2023/06/11

References

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fattaholmanan A, jazireiyan I, asgari J. Determining and improving the accuracy of orthometric and geodetic height with the NRTK system. case study of the Shamim system. JGST 2025; 14 (4) : 4
URL: http://jgst.issgeac.ir/article-1-1146-en.html

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Volume 14, Issue 4 (6-2025)

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