Assessment of forecast Vienna Mapping Function 1 for real-time tropospheric delay modeling in GNSS

2019 ◽  
Vol 93 (9) ◽  
pp. 1501-1514 ◽  
Author(s):  
Yubin Yuan ◽  
Lucas Holden ◽  
Allison Kealy ◽  
Suelynn Choy ◽  
Paweł Hordyniec
Keyword(s):  
Real Time ◽  
Mapping Function ◽  
Tropospheric Delay

scholarly journals Stochastic modelling of residual tropospheric delays / by Hassan Elobeid Ibrahim

2021 ◽  
Author(s):  
Hassan Elobeid Ibrahim
Keyword(s):  
Real Time ◽  
Mapping Function ◽  
Stochastic Modelling ◽  
Convergence Time ◽  
Data Series ◽  
Tropospheric Delay ◽  
Limiting Factor ◽  
Residual Component ◽  
Station Coordinates ◽  
Tropospheric Corrections

Real-time and near real-time precise point positioning (PPP) requires shorter solution convergence time. Residual tropospheric delay, which exists as a result of the limitations of current tropospheric correction models, is a limiting factor for fast PPP convergence. To overcome the limitations of existing tropospheric models, we proposed a new approach. In this approach, the bulk of the tropospheric delay is accounted for using an empirical model, while the residual component is accounted for stochastically. The analysis of many daily tropospheric residuals data series for stations spanning North America shows that the residual component can be accounted for using an exponential cosine model. A random walk (RW) model was also developed and used along with the NOAA tropospheric corrections with Vienna Mapping Function 1. It is shown that the RW improved the accuracy of station coordinates within the PPP convergence time by a few centimetres.

scholarly journals Stochastic modelling of residual tropospheric delays / by Hassan Elobeid Ibrahim

2021 ◽  
Author(s):  
Hassan Elobeid Ibrahim
Keyword(s):  
Real Time ◽  
Mapping Function ◽  
Stochastic Modelling ◽  
Convergence Time ◽  
Data Series ◽  
Tropospheric Delay ◽  
Limiting Factor ◽  
Residual Component ◽  
Station Coordinates ◽  
Tropospheric Corrections

Real-time and near real-time precise point positioning (PPP) requires shorter solution convergence time. Residual tropospheric delay, which exists as a result of the limitations of current tropospheric correction models, is a limiting factor for fast PPP convergence. To overcome the limitations of existing tropospheric models, we proposed a new approach. In this approach, the bulk of the tropospheric delay is accounted for using an empirical model, while the residual component is accounted for stochastically. The analysis of many daily tropospheric residuals data series for stations spanning North America shows that the residual component can be accounted for using an exponential cosine model. A random walk (RW) model was also developed and used along with the NOAA tropospheric corrections with Vienna Mapping Function 1. It is shown that the RW improved the accuracy of station coordinates within the PPP convergence time by a few centimetres.

An analysis of BDS-3 real-time PPP: Time transfer, positioning, and tropospheric delay retrieval

Measurement ◽  
2021 ◽  
Vol 172 ◽  
pp. 108871
Author(s):  
Yulong Ge ◽  
Shaoxin Chen ◽  
Tao Wu ◽  
Caoming Fan ◽  
Weijin Qin ◽  
...  
Keyword(s):  
Real Time ◽  
Tropospheric Delay ◽  
Time Transfer

scholarly journals A New Zenith Tropospheric Delay Grid Product for Real-Time PPP Applications over China

Sensors ◽  
2017 ◽  
Vol 18 (2) ◽  
pp. 65 ◽  
Author(s):  
Yidong Lou ◽  
Jinfang Huang ◽  
Weixing Zhang ◽  
Hong Liang ◽  
Fu Zheng ◽  
...  
Keyword(s):  
Real Time ◽  
Tropospheric Delay ◽  
Zenith Tropospheric Delay

scholarly journals QoS to QoE Mapping Function for Iptv Quality Assessement Based on Kohonen Map: A Pilot Study

2020 ◽  
Vol 21 (3) ◽  
pp. 181-190
Author(s):  
Jaroslav Frnda ◽  
Marek Durica ◽  
Mihail Savrasovs ◽  
Philippe Fournier-Viger ◽  
Jerry Chun-Wei Lin
Keyword(s):  
Real Time ◽  
Service Providers ◽  
Mapping Function ◽  
Video Stream ◽  
Assessment Method ◽  
End User ◽  
Quality Perception ◽  
Video Assessment ◽  
Kohonen Map

AbstractThis paper deals with an analysis of Kohonen map usage possibility for real-time evaluation of end-user video quality perception. The Quality of Service framework (QoS) describes how the network impairments (network utilization or packet loss) influence the picture quality, but it does not reflect precisely on customer subjective perceived quality of received video stream. There are several objective video assessment metrics based on mathematical models trying to simulate human visual system but each of them has its own evaluation scale. This causes a serious problem for service providers to identify a critical point when intervention into the network behaviour is needed. On the other hand, subjective tests (Quality of Experience concept) are time-consuming and costly and of course, cannot be performed in real-time. Therefore, we proposed a mapping function able to predict subjective end-user quality perception based on the situation in a network, video stream features and results obtained from the objective video assessment method.

scholarly journals Evaluation of Wet Mapping Functions Used in Modeling Tropospheric Propagation Delay Effect on GPS Measurements

2017 ◽  
Vol 11 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Sobhy Abdel-Monam Younes
Keyword(s):  
A Priori ◽  
Mapping Function ◽  
Propagation Delay ◽  
Radiosonde Data ◽  
Tropospheric Delay ◽  
Delay Effect ◽  
Gps Measurements ◽  
Mapping Functions ◽  
Significant Bias ◽  
Mapping Techniques

Background:The author compares several methods to map the a priori wet tropospheric delay of GNSS signals in Egypt from the zenith direction to lower elevations.Methods and Materials:The author compared the following mapping techniques against ray-traced delays computed for radiosonde profiles under the assumption of spherical symmetry: Saastamoinen, Hopfield, Black, Chao, Ifadis, Herring, Niell, Moffett, Black and Eisner and UNBabc mapping functions. Radiosonde data were computed from radiosonde stations at the Egyptian stations; in the south of Egypt, near the Mediterranean Sea, and near the Red Sea over a period of 5 years (2000-2005), most of the stations launched radiosonde twice daily, every day of the year. Moreover, data is received from the Egyptian Meteorology Authority.Results and Conclusion:The results indicate that currently, the saastamoinen mapping function should be used for all geodetic applications in Egypt, and if necessary, the Chao and Moffett mapping functions can serve as an acceptable replacement without introducing a significant bias into the station position.

scholarly journals Sensitivity of GNSS tropospheric gradients to processing options

2019 ◽  
Vol 37 (3) ◽  
pp. 429-446 ◽  
Author(s):  
Michal Kačmařík ◽  
Jan Douša ◽  
Florian Zus ◽  
Pavel Václavovic ◽  
Kyriakos Balidakis ◽  
...  
Keyword(s):  
Real Time ◽  
Elevation Angle ◽  
Mapping Function ◽  
Global Navigation Satellite Systems ◽  
Gradient Estimates ◽  
Post Processing ◽  
Data Set ◽  
Mapping Functions ◽  
Gradient Mapping

Abstract. An analysis of processing settings impacts on estimated tropospheric gradients is presented. The study is based on the benchmark data set collected within the COST GNSS4SWEC action with observations from 430 Global Navigation Satellite Systems (GNSS) reference stations in central Europe for May and June 2013. Tropospheric gradients were estimated in eight different variants of GNSS data processing using precise point positioning (PPP) with the G-Nut/Tefnut software. The impacts of the gradient mapping function, elevation cut-off angle, GNSS constellation, observation elevation-dependent weighting and real-time versus post-processing mode were assessed by comparing the variants by each to other and by evaluating them with respect to tropospheric gradients derived from two numerical weather models (NWMs). Tropospheric gradients estimated in post-processing GNSS solutions using final products were in good agreement with NWM outputs. The quality of high-resolution gradients estimated in (near-)real-time PPP analysis still remains a challenging task due to the quality of the real-time orbit and clock corrections. Comparisons of GNSS and NWM gradients suggest the 3∘ elevation angle cut-off and GPS+GLONASS constellation for obtaining optimal gradient estimates provided precise models for antenna-phase centre offsets and variations, and tropospheric mapping functions are applied for low-elevation observations. Finally, systematic errors can affect the gradient components solely due to the use of different gradient mapping functions, and still depending on observation elevation-dependent weighting. A latitudinal tilting of the troposphere in a global scale causes a systematic difference of up to 0.3 mm in the north-gradient component, while large local gradients, usually pointing in a direction of increasing humidity, can cause differences of up to 1.0 mm (or even more in extreme cases) in any component depending on the actual direction of the gradient. Although the Bar-Sever gradient mapping function provided slightly better results in some aspects, it is not possible to give any strong recommendation on the gradient mapping function selection.

scholarly journals Analysis and Comparison of GPS Precipitable Water Estimates between Two Nearby Stations on Tahiti Island

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5578
Author(s):  
Fangzhao Zhang ◽  
Jean-Pierre Barriot ◽  
Guochang Xu ◽  
Marania Hopuare
Keyword(s):  
Mapping Function ◽  
Precipitable Water ◽  
Satellite System ◽  
Tropospheric Delay ◽  
Horizontal Distance ◽  
International Gnss Service ◽  
Weighted Mean Temperature ◽  
The Difference ◽  
Global Navigation Satellite ◽  
The Impact

Since Bevis first proposed Global Positioning System (GPS) meteorology in 1992, the precipitable water (PW) estimates retrieved from Global Navigation Satellite System (GNSS) networks with high accuracy have been widely used in many meteorological applications. The proper estimation of GNSS PW can be affected by the GNSS processing strategy as well as the local geographical properties of GNSS sites. To better understand the impact of these factors, we compare PW estimates from two nearby permanent GPS stations (THTI and FAA1) in the tropical Tahiti Island, a basalt shield volcano located in the South Pacific, with a mean slope of 8% and a diameter of 30 km. The altitude difference between the two stations is 86.14 m, and their horizontal distance difference is 2.56 km. In this paper, Bernese GNSS Software Version 5.2 with precise point positioning (PPP) and Vienna mapping function 1 (VMF1) was applied to estimate the zenith tropospheric delay (ZTD), which was compared with the International GNSS Service (IGS) Final products. The meteorological parameters sourced from the European Center for Medium-Range Weather Forecasts (ECMWF) and the local weighted mean temperature ( T m ) model were used to estimate the GPS PW for three years (May 2016 to April 2019). The results show that the differences of PW between two nearby GPS stations is nearly a constant with value 1.73 mm. In our case, this difference is mainly driven by insolation differences, the difference in altitude and the wind being only second factors.

Single station GNSS tomography as a replacement of mapping function for high precision troposphere radio wave delay correction

2020 ◽  
Author(s):  
Feng Peng ◽  
Li Fei ◽  
Jean-Pierre Barriot ◽  
Yan Jianguo ◽  
Zhang Fangzhao ◽  
...  
Keyword(s):  
Radio Wave ◽  
Time Resolution ◽  
Mapping Function ◽  
Satellite Tracking ◽  
Tropospheric Delay ◽  
High Time Resolution ◽  
Signal Delay ◽  
Mapping Functions ◽  
Single Station ◽  
Delay Correction

<p>With its relatively low cost, high availability and continuous observation ability, zenith delays from GPS combined with mapping function have been used in satellite tracking media calibration since early 2000. The mapping functions are used to model elevation dependency of radio wave delays in the troposphere. It assumes that the ratio of signal slant delay over zenith delay is less variable w.r.t time and location than the signal delay itself. Thus the parameters of signal delay elevation dependency can be modeled and unknowns of the tropospheric delay were reduced. However, the parameterization comes with a loss of accuracy. For example, the state-of-art VMF series mapping functions have a time resolution of 6 hours, which means variations that took place in less than 6 hours are smoothed. Nowadays GPS has evolved to multi-constellation GNSS with many more satellites in visibility. Here we propose a single station GNSS tomography algorithm for radio wave delay correction by directly using slant delays. This algorithm can extract the information of the troposphere variations in all the signal directions of GNSS observations with high time resolution. Thus it will be beneficial to the radio wave delay correction of precise satellite tracking. We assess the performance of this algorithm with a collocated water vapor radiometer.</p>

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