scholarly journals Reply to Comment on Choi et al. Correlation between Ionospheric TEC and the DCB Stability of GNSS Receivers from 2014 to 2016. Remote Sens. 2019, 11, 2657

2020 ◽  
Vol 12 (21) ◽  
pp. 3510
Author(s):  
Byung-Kyu Choi ◽  
Dong-Hyo Sohn ◽  
Sang Jeong Lee
Keyword(s):  
Clear Correlation ◽  
Electron Content ◽  
Total Electron ◽  
Differential Code Bias ◽  
Ionospheric Variability ◽  
Ionospheric Total Electron Content ◽  
Gnss Receivers ◽  
Code Bias ◽  
Receiver Dcb

Choi et al. (2019) suggested that ionospheric total electron content (TEC) and receiver differential code bias (rDCB) stability have a strong correlation during a period of two years from 2014 to 2016. This article is a response to Zhong et al. (2020), who pointed out that the long-term variations of the GPS DCBs are mainly attributed to the satellite replacement rather than the ionospheric variability. In this issue, we investigated the center for orbit determination in Europe (CODE) Global Ionosphere Maps (GIM) products from 2000 to 2020. In this study, changes in TEC and receiver DCB (rDCB) root mean squares (RMS) at Bogota (BOGT) station still have a clear correlation. In addition, there was a moderate correlation between satellite DCB RMS and rDCB RMS. As a result, we suggest that rDCB can be affected simultaneously by GPS sDCB as well as ionospheric activity.

scholarly journals Comment on Choi et al. Correlation between Ionospheric TEC and the DCB Stability of GNSS Receivers from 2014 to 2016. Remote Sens. 2019, 11, 2657

2020 ◽  
Vol 12 (21) ◽  
pp. 3496 ◽  
Author(s):  
Jiahao Zhong ◽  
Jiuhou Lei ◽  
Xinan Yue
Keyword(s):  
Satellite System ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Variability ◽  
Gnss Receivers ◽  
Code Bias ◽  
Receiver Dcb ◽  
Global Navigation Satellite ◽  
Long Term Variations

Choi et al. (2019) analyzed the correlation between the ionospheric total electron content (TEC) and the Global Navigation Satellite System (GNSS) receiver differential code bias (DCB) and concluded that the long-term variations of the receiver DCB are caused by the corresponding variations in the ionosphere. Unfortunately, their method is problematic, resulting in conclusions that are not useful. The long-term variations of the Global Positioning System (GPS) DCBs are primarily attributed to the GPS satellite replacement with different satellite block series under the zero-mean constraint condition, rather than the ionospheric variability.

scholarly journals Validation and application of optimal ionospheric shell height model for single-site TEC estimation

2018 ◽  
Author(s):  
Jiaqi Zhao ◽  
Chen Zhou
Keyword(s):  
Estimation Error ◽  
Shell Height ◽  
Practical Method ◽  
Electron Content ◽  
International Gnss Service ◽  
Total Electron ◽  
Dense Networks ◽  
Gnss Receivers ◽  
Code Bias ◽  
Height Model

Abstract. We recently proposed a method to establish optimal ionospheric shell height model based on the international GNSS service (IGS) station data and the differential code bias (DCB) provided by Center for Orbit Determination in Europe (CODE) during the time from 2003 to 2013. This method is very promising for DCB and accurate total electron content (TEC) estimation by comparing to traditional fixed shell height method. However, this method is basically feasible only for IGS stations. In this study, we investigate how to apply the optimal ionospheric shell height derived from IGS station to non-IGS stations or isolated GNSS receivers. The intuitional and practical method to estimate TEC of non-IGS stations is based on optimal ionospheric shell height derived from nearby IGS stations. To validate this method, we selected two dense networks of IGS stations located in US and Europe region. Two optimal ionospheric shell height models are established by two reference stations, namely GOLD and PTBB, which are located at the approximate center of two selected regions. The predicted daily optimal ionospheric shell heights by the two models are applied to other IGS stations around these two reference stations. Daily DCBs are calculated according to these two optimal shell heights and compared to respective DCBs released by CODE. The validation results of this method present that 1) Optimal ionospheric shell height calculated by IGS stations can be applied to its nearby non-IGS stations or isolated GNSS receivers for accurate TEC estimation. 2) As the distance away from the reference IGS station becomes larger, the DCB estimation error becomes larger. The relation between the DCB estimation error and the distance is generally linear.

scholarly journals MGR-DCB: A Precise Model for Multi-Constellation GNSS Receiver Differential Code Bias

2015 ◽  
Vol 69 (4) ◽  
pp. 698-708 ◽  
Author(s):  
Mohamed Abdelazeem ◽  
Rahmi N. Çelik ◽  
Ahmed El-Rabbany
Keyword(s):  
Total Electron Content ◽  
Satellite System ◽  
Mean Difference ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
International Gnss Service ◽  
Total Electron ◽  
Differential Code Bias ◽  
Gnss Receiver ◽  
Code Bias

In this study, we develop a Multi-constellation Global Navigation Satellite System (GNSS) Receiver Differential Code Bias (MGR-DCB) model. The model estimates the receiver DCBs for the Global Positioning System (GPS), BeiDou and Galileo signals from the ionosphere-corrected geometry-free linear combinations of the code observations. In order to account for the ionospheric delay, a Regional Ionospheric Model (RIM) over Europe is developed. GPS observations from 60 International GNSS Servoce (IGS) and EUREF reference stations are processed in the Bernese-5·2 Precise Point Positioning (PPP) module to estimate the Vertical Total Electron Content (VTEC). The RIM has spatial and temporal resolutions of 1° × 1° and 15 minutes, respectively. The receiver DCBs for three stations from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) are estimated for three different days. The estimated DCBs are compared with the MGEX published values. The results show agreement with the MGEX values with mean difference and Root Mean Square Error (RMSE) values less than 1 ns. In addition, the combined GPS, BeiDou and Galileo VTEC values are evaluated and compared with the IGS Global Ionospheric Maps (IGS-GIM) counterparts. The results show agreement with the GIM values with mean difference and RMSE values less than 1 Total Electron Content Unit (TECU).

scholarly journals Advantages of Uncombined Precise Point Positioning with Fixed Ambiguity Resolution for Slant Total Electron Content (STEC) and Differential Code Bias (DCB) Estimation

2020 ◽  
Vol 12 (2) ◽  
pp. 304 ◽  
Author(s):  
Jin Wang ◽  
Guanwen Huang ◽  
Peiyuan Zhou ◽  
Yuanxi Yang ◽  
Qin Zhang ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Ambiguity Resolution ◽  
Precise Point Positioning ◽  
Electron Content ◽  
Total Electron ◽  
Differential Code Bias ◽  
Ionosphere Modeling ◽  
Code Bias ◽  
Point Positioning ◽  
Slant Total Electron Content

The determination of slant total electron content (STEC) between satellites and receivers is the first step for establishing an ionospheric model. However, the leveling errors, caused by the smoothed ambiguity solutions in the carrier-to-code leveling (CCL) method, degrade the performance of ionosphere modeling and differential code bias (DCB) estimation. To reduce the leveling errors, an uncombined and undifferenced precise point positioning (PPP) method with ambiguity resolution (AR) was used to directly extract the STEC. Firstly, the ionospheric observables were estimated with CCL, PPP float-ambiguity solutions, and PPP fixed-ambiguity solutions, respectively, to analyze the short-term temporal variation of receiver DCB in zero or short baselines. Then, the global ionospheric map (GIM) was modeled using three types of ionospheric observables based on the single-layer model (SLM) assumption. Compared with the CCL method, the slight variations of receiver DCBs can be obviously distinguished using high precise ionospheric observables, with a 58.4% and 71.2% improvement of the standard deviation (STD) for PPP float-ambiguity and fixed-ambiguity solutions, respectively. For ionosphere modeling, the 24.7% and 27.9% improvements for posteriori residuals were achieved for PPP float-ambiguity and fixed-ambiguity solutions, compared to the CCL method. The corresponding improvement for residuals of the vertical total electron contents (VTECs) compared with the Center for Orbit Determination in Europe (CODE) final GIM products in global accuracy was 9.2% and 13.7% for PPP float-ambiguity and fixed-ambiguity solutions, respectively. The results show that the PPP fixed-ambiguity solution is the best one for the GIM product modeling and satellite DCBs estimation.

scholarly journals Estimativa e Propagação de Valores de DCB C1C-C2W de um Receptor GPS com Vistas a Correção de Ordem Superior do Efeito Ionosférico

2020 ◽  
Vol 72 (3) ◽  
pp. 445-459
Author(s):  
Fabiane Piovesan de Moraes Cordeiro ◽  
Tiago Lima Rodrigues ◽  
Luiz Danilo Damasceno Ferreira
Keyword(s):  
Total Electron Content ◽  
Electron Content ◽  
Total Electron ◽  
Differential Code Bias ◽  
Code Bias

Quando se almeja maior acurácia no posicionamento GNSS, é imprescindível a correção dos efeitos de ordem superior da refração ionosférica. O erro associado à ionosfera é diretamente proporcional ao conteúdo total de elétrons (Total Electron Content – TEC) presentes na atmosfera e inversamente proporcional à frequência do sinal. Ao usar a combinação linear livre de geometria com as observações advindas dos códigos, o cálculo do TEC é influenciado pelo erro sistemático conhecido como tendência diferencial devido ao atraso do código (Differential Code Bias – DCB). Esta pesquisa tem como principal objetivo a determinação do DCB C1C-C2W de um receptor GPS, utilizando a técnica da Simples Diferença, para utilização no cálculo do TEC e na correção dos efeitos de ordem superior da refração ionosférica diretamente em campo. Os experimentos foram realizados no contexto do PPP (Posicionamento por Ponto Preciso). Experimentos adicionais considerando a propagação dos valores de DCB por três e quatro semanas foram conduzidos. Isso, a fim de verificar a possibilidade de diminuir a frequência de idas a campo para o cálculo dos valores de DCB. Os resultados obtidos considerando-se a correção de ordem superior da refração ionosférica mostram uma melhorana ordem do milímetro na direção leste-oeste e na direção normal ao elipsoide, quando comparados com o processamento considerando apenas as correções de primeira ordem. Para a componente norte-sul, a melhora apresentou-se na ordem do centímetro. Quando utilizados os DCBs propagados, os resultados apresentaram uma acurácia média no PPP de 0,2 cm para latitude, 1,4 cm para longitude e 1,5 cm para altitude.

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