UNB3m_pack: a neutral atmosphere delay package for radiometric space techniques

Leandro, Rodrigo; Langley, Richard B.; Santos, Marcelo C.

doi:10.1007/s10291-007-0077-5

Cited by 160 publications

(80 citation statements)

References 2 publications

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“…For both single and dual-PPP models, the UNB3 tropospheric model, consisting of the Saastamoinen vertical propagation delay model and Niell mapping function, is used to account for the dry tropospheric component (Leandro et al 2008). As The effects of ocean loading, Earth tide, carrier-phase windup, sagnac, relativity, and satellite antenna phasecenter variations are rigorously modeled as detailed in Kouba (2009).…”

Section: ( D T + D ) -C D T -C ( F ) + C [ S I S B ] + T + I + E (6)mentioning

confidence: 99%

Evaluation of Quad-Constellation GNSS Precise Point Positioning in Egypt

Manaily

Rabbou

El-Shazly

et al. 2017

Artificial Satellites

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ABSTRACT:Commonly, relative GPS positioning technique is used in Egypt for precise positioning applications. However, the requirement of a reference station is usually problematic for some applications as it limits the operational range of the system and increases the system cost and complexity On the other hand; the single point positioning is traditionally used for low accuracy applications such as land vehicle navigation with positioning accuracy up to 10 meters in some scenarios which caused navigation problems especially in downtown areas. Recently, high positioning accuracy can be obtained through Precise Point Positioning (PPP) technique in which only once GNSS receiver is used. However, the major drawback of PPP is the long convergence time to reach to the surveying grade accuracy compared to the existing relative techniques. Moreover, the PPP accuracy is significantly degraded due to shortage in satellite availability in urban areas. To overcome these limitations, the quad constellation GNSS systems namely; GPS.GLONASS, Galileo and BeiDou can be combined to increase the satellite availability and enhance the satellite geometry which in turn reduces the convergence time. In Egypt, at the moment, the signals of both Galileo and BeiDou could be logged with limited number of satellites up to four and six satellites for both Systems respectively. In this paper, we investigated the performance of the Quad-GNSS positioning in both dual-and single-frequency ionosphere free PPP modes for both high accurate and low cost navigation application, respectively. The performance of the developed PPP models will be investigated through GNSS data sets collected at three Egyptian cities namely, Cairo, Alexandria and Aswan.

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Section: ( D T + D ) -C D T -C ( F ) + C [ S I S B ] + T + I + E (6)mentioning

confidence: 99%

Evaluation of Quad-Constellation GNSS Precise Point Positioning in Egypt

Manaily

Rabbou

El-Shazly

et al. 2017

Artificial Satellites

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“…Strictly, the UNB3m model is not a specific T m model, but it can be used to calculate T m from the following equation (Leandro et al, 2008):…”

Section: B1 Unb3mmentioning

confidence: 99%

“…More details for these three models can be found in Appendix B. Note that UNB3m and GPT2w are not specific T m models even though they can output T m values (Leandro et al, 2008;Böhm et al, 2015). In addition, no comprehensive intercomparison with the same reference T m has been carried out among existing empirical T m models.…”

Section: Introductionmentioning

confidence: 99%

A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

Hé

Wang

et al. 2017

Atmos. Meas. Tech.

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Abstract. The Global Positioning System (GPS) is a powerful atmospheric observing system for determining precipitable water vapour (PWV). In the detection of PWV using GPS, the atmospheric weighted mean temperature (T m ) is a crucial parameter for the conversion of zenith tropospheric delay (ZTD) to PWV since the quality of PWV is affected by the accuracy of T m . In this study, an improved voxel-based T m model, named GWMT-D, was developed using global reanalysis data over a 4-year period from 2010 to 2013 provided by the United States National Centers for Environmental Prediction (NCEP). The performance of GWMT-D was assessed against three existing empirical T m models -GTm-III, GWMT-IV, and GTm_N -using different data sources in 2014 -the NCEP reanalysis data, surface T m data provided by Global Geodetic Observing System and radiosonde measurements. The results show that the new GWMT-D model outperforms all the other three models with a root-meansquare error of less than 5.0 K at different altitudes over the globe. The new GWMT-D model can provide a practical alternative T m determination method in real-time GPS-PWV remote sensing systems.

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“…The MLAMBDA algorithm is applied for ambiguity resolution (Chang et al 2005). The UNB3m model is used for a priori tropospheric delays computations (Leandro et al 2008). …”

Section: Functional Model Of Precise Positioningmentioning

confidence: 99%

Study on reliable GNSS positioning with intense TEC fluctuations at high latitudes

Sieradzki

Paziewski

2015

GPS Solut

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The study presents the influence of strong total electron content (TEC) fluctuations occurring at high latitudes on rapid static positioning. The authors propose an algorithm mitigating the impact of dynamic temporal changes in electron content using the rate of TEC corrections. It consists of modifying the observations using the measured rate of TEC variations and hence allows reducing the number of parameters to one ionospheric delay of a reference epoch per satellite and per session. An analysis was carried out for a typical quiet day in solar minimum on September 6, 2009 and a disturbed day during high solar activity on March 17, 2013. For a standard geometry-based relative model with weighted ionosphere and troposphere, the results confirmed the dramatic drop of ambiguity resolution efficiency during a violent space weather event. The results obtained for the new algorithm, however, demonstrate its wide applicability and a 10-fold improvement in ambiguity success rate during the disturbed day.

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UNB3m_pack: a neutral atmosphere delay package for radiometric space techniques

Cited by 160 publications

References 2 publications

Evaluation of Quad-Constellation GNSS Precise Point Positioning in Egypt

Evaluation of Quad-Constellation GNSS Precise Point Positioning in Egypt

A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

Study on reliable GNSS positioning with intense TEC fluctuations at high latitudes

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