Estimation accuracy analysis of zenith tropospheric delays obtained by precise point positioning technique

Abstract Because of the dynamics of the GPS technique used in different domains like geodesy, near real-time GPS meteorology, geodynamics, the precise point positioning (PPP) becomes more than a powerful method for determining the position, or the delay caused by the atmosphere. The main idea of this method is that we need only one receiver – preferably that have dual frequencies pseudorange and carrier-phase capabilities – to obtain the position. Because we are using only one receiver the majority of the residuals that are eliminated in double differencing method, we have to estimate them in PPP. The development of the PPP method allows us, to use precise satellite clock estimates, and precise orbits, resulting in a much more efficient way to deal with the disadvantages of this technique, like slow convergence time, or ambiguity resolution. Because this two problem are correlated, to achieve fast convergence we need to resolve the problem of ambiguity resolution. But the accuracy of the PPP results are directly influenced by presence of the uncalibrated phase delays (UPD) originating in the receivers and satellites. In this article we present the GPS errors and biases, the zenith wet delay and the necessary time for obtaining the convergence. The necessary correction are downloaded by using the IGS service.

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Analysis of web-based online services for GPS relative and precise point positioning techniques

Boletim de Ciências Geodésicas ◽

10.1590/s1982-21702013000200003 ◽

2013 ◽

Vol 19 (2) ◽

pp. 191-207 ◽

Cited By ~ 14

Author(s):

Taylan Ocalan ◽

Bahattin Erdogan ◽

Nursu Tunalioglu

Keyword(s):

Precise Point Positioning ◽

Gps Data ◽

Accuracy Analysis ◽

Engineering Applications ◽

Online Services ◽

Data Set ◽

Web Based ◽

Test Study ◽

Processing Software ◽

Point Positioning

Nowadays, Global Positioning System (GPS) has been used effectively in several engineering applications for the survey purposes by multiple disciplines. Web-based online services developed by several organizations; which are user friendly, unlimited and most of them are free; have become a significant alternative against the high-cost scientific and commercial software on achievement of post processing and analyzing the GPS data. When centimeter (cm) or decimeter (dm) level accuracies are desired, that can be obtained easily regarding different quality engineering applications through these services. In this paper, a test study was conducted at ISKI-CORS network; Istanbul-Turkey in order to figure out the accuracy analysis of the most used web based online services around the world (namely OPUS, AUSPOS, SCOUT, CSRS-PPP, GAPS, APPS, magicGNSS). These services use relative and precise point positioning (PPP) solution approaches. In this test study, the coordinates of eight stations were estimated by using of both online services and Bernese 5.0 scientific GPS processing software from 24-hour GPS data set and then the coordinate differences between the online services and Bernese processing software were computed. From the evaluations, it was seen that the results for each individual differences were less than 10 mm regarding relative online service, and less than 20 mm regarding precise point positioning service. The accuracy analysis was gathered from these coordinate differences and standard deviations of the obtained coordinates from different techniques and then online services were compared to each other. The results show that the position accuracies obtained by associated online services provide high accurate solutions that may be used in many engineering applications and geodetic analysis.

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Multiple Ambiguity Datum Precise Point Positioning Technique Using Multi-Constellation GNSS: GPS, GLONASS, Galileo and BeiDou

Positioning ◽

10.4236/pos.2015.63004 ◽

2015 ◽

Vol 06 (03) ◽

pp. 32-43 ◽

Cited By ~ 1

Author(s):

Mahmoud Abd Rabbou

Keyword(s):

Precise Point Positioning ◽

Positioning Technique ◽

Point Positioning

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Analysis on the Impacts of Slant Tropospheric Delays on Precise Point Positioning

Applied Sciences ◽

10.3390/app9224884 ◽

2019 ◽

Vol 9 (22) ◽

pp. 4884

Author(s):

Chunbao Xiong ◽

Lina Yu ◽

Lewen Zhao

Keyword(s):

Carrier Phase ◽

Precise Point Positioning ◽

Three Dimensional ◽

Dimensional Accuracy ◽

Tropospheric Delay ◽

Horizontal Gradients ◽

Beidou System ◽

Point Positioning ◽

Tropospheric Corrections ◽

Tropospheric Delays

Tropospheric delay is one main factor affecting the accuracy of precise point positioning (PPP) ambiguity-float and fixed solutions. Investigations mainly focused on evaluating the contributions of tropospheric corrections to the accuracy and reliability of PPP solutions. The tropospheric corrections generally contained the zenith tropospheric delay (ZTD) and the horizontal gradients estimated from relative positioning or PPP. However, the estimated tropospheric delays can be partly absorbed by the carrier phase residuals if the stochastic model is not well-defined. Therefore, along with the ZTD and horizontal gradients, the carrier phase residuals from PPP backward filter are considered to reconstruct slant tropospheric delay (STD). Based on the proposed STD model, its marginal effects on GPS PPP were investigated. Results indicated that the consideration of carrier phase residuals for STD modeling can improve the three-dimensional accuracy to 0.5 cm/1 cm/1.2 cm in the South/North/Up (N/E/U) components. Then, the effects of internal and external STD corrections on PPP float and fixed solutions were analyzed. Compared to the ZTD + gradients augmentation, STD corrections from the same station could improve the PPP accuracy by 51%/51%/60%; the large improvements were because the multipath error and observation noise were eliminated. In comparison, the improvement was 14%/28%/31% using external STD corrections, which indicated the effects of unmodeled tropospheric errors in the phase residuals. The ambiguity-fixing results indicated that the fixing rate of PPP ambiguity was increased by 30% with STD augmentation. As the BeiDou System (BDS) suffered longer convergence than that of GPS, the benefits of STD modeling to the BDS observations were also validated. Overall, the results validated the performance of STD-augmented PPP, which demonstrated the potential application of high-accuracy troposphere products.

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