scholarly journals Space State Representation Product Evaluation in Satellite Position and Receiver Position Domain

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3791
Author(s):  
Renata Pelc-Mieczkowska ◽  
Dariusz Tomaszewski
Keyword(s):  
Real Time ◽  
Single Point ◽  
Product Evaluation ◽  
Space Representation ◽  
Satellite Orbits ◽  
Time Service ◽  
Satellite Position ◽  
Point Position ◽  
Broadcast Ephemeris ◽  
The Impact

In Global Navigation Satellite Systems (GNSS) positioning, important terms in error budget are satellite orbits and satellite clocks correction errors. International services are developing and providing models and correction to minimize the influence of these errors both in post-processing and real-time applications. The International GNSS Service (IGS) Real-Time Service (RTS) provides real-time orbits and clock corrections for the broadcast ephemeris. Real-time products provided by IGS are generated by different analysis centres using different algorithms. In this paper, four RTS products—IGC01, CLK01, CLK50, and CLK90—were evaluated and analysed. To evaluate State Space Representation (SSR) products’ GPS satellites, the analyses were made in three variants. In the first approach, geocentric real-time Satellite Vehicle (SV) coordinates and clock corrections were calculated. The obtained results were compared with the final IGS, ESA, GFZ, and GRG ephemerides. The second approach was to use the corrected satellite positions and clock corrections to determine the Precise Point Position (PPP) of the receiver. In the third analysis, the impact of SSR corrections on receiver Single Point Position (SPP) was evaluated. The first part of the research showed that accuracy of the satellite position is better than 10 cm (average 3 to 5 cm), while in the case of clock corrections, mean residuals range from 2 cm to 17 cm. It should be noted that the errors of the satellites positions obtained from one stream differ depending on the reference data used. This shows the need for an evaluation of correction streams in the domain of the receiver position. In the case of PPP in a kinematic mode, the tests allowed to determine the impact that the use of different streams has on the final positioning results. These studies showed differences between specific streams, which could not be seen in the first study. The best results (3D RMS at 0.13 m level) were obtained for the CLK90 stream, while for IGC01, the results were three times worse. The SPP tests clearly indicate that regardless of the selected SSR stream, one can see a significant improvement in positioning accuracy as compared to positioning results using only broadcast ephemeris.

scholarly journals Considering different recent advancements in GNSS on real-time zenith troposphere estimates

GPS Solutions ◽  
2020 ◽  
Vol 24 (4) ◽  
Author(s):  
Tomasz Hadas ◽  
Thomas Hobiger ◽  
Pawel Hordyniec
Keyword(s):  
Real Time ◽  
Weighting Function ◽  
Functional Model ◽  
Processing Parameters ◽  
Gradient Estimation ◽  
International Gnss Service ◽  
Total Delay ◽  
Time Service ◽  
Gnss Meteorology ◽  
The Impact

Abstract Global navigation satellite system (GNSS) remote sensing of the troposphere, called GNSS meteorology, is already a well-established tool in post-processing applications. Real-time GNSS meteorology has been possible since 2013, when the International GNSS Service (IGS) established its real-time service. The reported accuracy of the real-time zenith total delay (ZTD) has not improved significantly over time and usually remains at the level of 5–18 mm, depending on the station and test period studied. Millimeter-level improvements are noticed due to GPS ambiguity resolution, gradient estimation, or multi-GNSS processing. However, neither are these achievements combined in a single processing strategy, nor is the impact of other processing parameters on ZTD accuracy analyzed. Therefore, we discuss these shortcomings in detail and present a comprehensive analysis of the sensitivity of real-time ZTD on processing parameters. First, we identify a so-called common strategy, which combines processing parameters that are identified to be the most popular among published papers on the topic. We question the popular elevation-dependent weighting function and introduce an alternative one. We investigate the impact of selected processing parameters, i.e., PPP functional model, GNSS selection and combination, inter-system weighting, elevation-dependent weighting function, and gradient estimation. We define an advanced strategy dedicated to real-time GNSS meteorology, which is superior to the common one. The a posteriori error of estimated ZTD is reduced by 41%. The accuracy of ZTD estimates with the proposed strategy is improved by 17% with respect to the IGS final products and varies over stations from 5.4 to 10.1 mm. Finally, we confirm the latitude dependency of ZTD accuracy, but also detect its seasonality.

scholarly journals Analysis on the Potential Performance of GPS and Galileo Precise Point Positioning using Simulated Real-Time Products

2018 ◽  
Vol 72 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Francesco Basile ◽  
Terry Moore ◽  
Chris Hill
Keyword(s):  
Real Time ◽  
Precise Point Positioning ◽  
Satellite System ◽  
Convergence Time ◽  
Alternative Methods ◽  
International Gnss Service ◽  
Binary Offset Carrier ◽  
Time Service ◽  
Point Positioning ◽  
The Impact

With the evolving Global Navigation Satellite System (GNSS) landscape, the International GNSS Service (IGS) has started the Multi-GNSS Experiment (MGEX) to produce precise products for new generation systems. Various analysis centres are working on the estimation of precise orbits, clocks and bias for Galileo, Beidou and Quasi-Zenith Satellite System (QZSS) satellites. However, at the moment these products can only be used for post-processing applications. Indeed, the IGS Real-Time service only broadcasts Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) corrections. In this research, a simulator of multi-GNSS observations and real-time precise products has been developed to analyse the performance of GPS-only, Galileo-only and GPS plus Galileo Precise Point Positioning (PPP). The error models in the simulated orbits and clocks were based on the difference between the GPS Real-Time and the Final products. Multiple scenarios were analysed, considering different signals combined in the Ionosphere Free linear combination. Results in a simulated open area environment show better performance of the Galileo-only case over the GPS-only case. Indeed, up 33% and 29% of improvement, respectively, in the accuracy level and convergence time can be observed when using the full Galileo constellation compared to GPS. The dual constellation case provides good improvements, in particular in the convergence time (47% faster than GPS). This paper will also consider the impact of different linear combinations of the Galileo signals, and the potential of the E5 Alternative Binary Offset Carrier (AltBOC) signal. Even though it is significantly more precise than E5a, the PPP performance obtained with the Galileo E1-E5a combination is either better or similar to the one with Galileo E1-E5. The reason for this inconsistency was found in the use of the ionosphere free combination with E1. Finally, alternative methods of ionosphere error mitigation are considered in order to ensure the best possible positioning performance from the Galileo E5 signal in multi-frequency PPP.

scholarly journals Program Evaluation of a Nationwide Continuing Professional Development (CPD) Program in Korean Public Health and Medical Institutions

2021 ◽  
Author(s):  
Claire Junga Kim ◽  
Hyojung Mo ◽  
Ji Young Lee
Keyword(s):  
Public Health ◽  
Professional Development ◽  
Real Time ◽  
Process Evaluation ◽  
Continuing Professional Development ◽  
Product Evaluation ◽  
Training Centre ◽  
Cipp Model ◽  
Medical Institutions ◽  
The Impact

Abstract Background: Education & Training Centre for Public Healthcare of the National Medical Centre plays a key role in providing continuing professional development (CPD) to 221 public health and medical institutions in South Korea. To assess the realisation of the Center’s core value and of the intended chages, program evaluations is needed. The context, input, process, and product (CIPP) model is particularly suitable for evaluating CPD in public sector as it allows to recognise the dynamic nature of the programme environment.Methods: This research applied the CIPP model to the evaluation of CPD programmes, particulary abdominal and thracic ultrasond programme implemented in 2017 and 2018. Data were collected from 2017 to 2019. The programme and its feedback were reviewed in context evaluation. Based on this, the subsequent programme strategy was established in input evaulation. Observing the programme in real time and recording progress was followed in process evaluation. Finally, the outcome and impact of the programme were reviewed and compared with baseline data in product evaluation. Results: In context evaluation, the educational needs of the recipients of the Centre’s CPD programme, impediments that inhibit participation in education, and resources that the Centre can utilise were identified through online survey, focus group interviews, expert consultation. Through input evaluation, we identified the best alternative that satisfied all pre-selected criteria, which were responsiveness to priority system needs, potential effectiveness, fit with existing services, affordability, and administrative feasibility. Observing the programme in real time and recording progress was conducted in process evaluation and shows that the improved programme went as planned, and even had to be expanded due to increased demand. The impact of the programme was measured, interpreted, and assessed in the product evaluation. As the review committee decided that the intended change has occurred, the Centre decided to maintain the program. Conclusions: Thorough evaluations are necessary to unlock the potential benefits of CPD. The CIPP methodology is valuable to execute formative as well as summative evaluations. The CIPP model is especially useful for securing accountability data for large-scale nation-wide educational programmes supplied by public funds.

scholarly journals The Prediction of Geocentric Corrections during Communication Link Outages in PPP

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 602
Author(s):  
Joanna Janicka ◽  
Dariusz Tomaszewski ◽  
Jacek Rapinski ◽  
Marcin Jagoda ◽  
Miloslawa Rutkowska
Keyword(s):  
Real Time ◽  
Precise Point Positioning ◽  
Space Representation ◽  
The Internet ◽  
Communication Link ◽  
Value Change ◽  
Degree Polynomial ◽  
International Gnss Service ◽  
Time Service ◽  
State Space Representation

The International GNSS Service (IGS) real-time service (RTS) provides access to real-time precise products. State-Space Representation (SSR) products are disseminated through the Internet using the Networked Transport of the RTCM (Radio Technical Commission for Maritime Services) via the Internet Protocol (NTRIP). However, communication outages caused by a loss of the communication link during ephemeris changes can occur. Unfortunately, any break in providing orbit and clock corrections affects the possibility to perform precise point positioning. To eliminate this problem, various methods have been developed and presented in the literature. The solution proposed by the authors is to directly predict geocentric corrections. This manuscript presents the results and analysis of geocentric correction predictions under two scenarios: the first between the IODE (issue of data ephemeris) value change and the second where prediction must be done for epochs containing a change in IODE ephemeris. In this case, the prediction uses data from a previous message. The Root Mean Square (RMS) values calculated based on the differences between the true correction values and the predicted geocentric corrections using a linear function, a second-degree polynomial and a constant value do not differ significantly. The numerical results show that, in most cases, maintaining the constant value of the last registered SSR correction is the best option.

scholarly journals Real-Time Detection of Orbital Maneuvers Using Epoch-Differenced Carrier Phase Observations and Broadcast Ephemeris Data: A Case Study of the BDS Dataset

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4584 ◽  
Author(s):  
Rui Tu ◽  
Rui Zhang ◽  
Lihong Fan ◽  
Junqiang Han ◽  
Pengfei Zhang ◽  
...  
Keyword(s):  
Real Time ◽  
Carrier Phase ◽  
Single Point ◽  
Satellite System ◽  
Velocity Estimation ◽  
Navigation Satellite ◽  
Orbital Maneuvers ◽  
Broadcast Ephemeris ◽  
Real Time Detection ◽  
Global Navigation Satellite

The orbital maneuvers of the global navigation satellite system (GNSSs) have a significant influence on the performance of the precise positioning, navigation, and timing (PNT) services. Because the Chinese BeiDou Navigation Satellite System (BDS) has three types of satellites in the geostationary orbit (GEO), inclined geosynchronous orbit (IGSO), and medium earth orbit (MEO) maneuvers occur more frequently. Thus, it is essential to determine an effective approach for the detection of orbital maneuvers. This study proposes a method for the detection of orbital maneuvers using epoch-differenced carrier phase observations and broadcast ephemeris data. When using the epoch-differenced velocity estimation as a basic data solution model, the time discrimination and satellite identification factors are defined and used for the real-time detection of the beginning and the pseudorandom noise code (PRN) of satellites. The datasets from four GNSS stations (WUH1, BJF1, POHN, CUT0) from the year 2016 were collected and analyzed. The validations showed that the beginning, the PRN of the orbital maneuver of the satellite can be precisely detected in real time for all GEO, IGSO, and MEO satellites, and the detected results also showed good consistency, with the beginning time at a difference of 1–2 min across different stations. The proposed approach was observed to be more sensitive, and the detected beginning time was about 30 min earlier than the single point positioning approach when the high-precision carrier phase observation was used. Thus, orbital maneuvering can be accurately detected by the proposed method. It not only improves the utilization of the collected data but also improves the performance of PNT services.

scholarly journals Analysis and Assessment of BDS-2 and BDS-3 Broadcast Ephemeris: Accuracy, the Datum of Broadcast Clocks and Its Impact on Single Point Positioning

2020 ◽  
Vol 12 (13) ◽  
pp. 2081 ◽  
Author(s):  
Guoqiang Jiao ◽  
Shuli Song ◽  
Yangyang Liu ◽  
Ke Su ◽  
Na Cheng ◽  
...  
Keyword(s):  
Single Point ◽  
Satellite Orbit ◽  
Satellite System ◽  
Satellite Orbits ◽  
Satellite Clock ◽  
Single Point Positioning ◽  
Broadcast Ephemeris ◽  
North East ◽  
Point Positioning ◽  
Broadcast Orbit

For the global ordinary users, the broadcast ephemeris plays important roles in positioning, navigation and timing (PNT) services. With the construction of a new generation of the BeiDou navigation satellite system (BDS), the development of BDS has entered the era of globalization. It is meaningful for global users to analyze and assess the BDS-2 and BDS-3 broadcast ephemeris. Therefore, the satellite orbits and clock offsets calculated by broadcast ephemeris are compared with the precise orbit and clock offset products provided by three analysis centers (i.e., Helmholtz Centre Potsdam German Research Center for Geosciences (GFZ), Wuhan University (WHU) and Shanghai Astronomical Observatory (SHA)), and the corresponding signal-in-space range error (SISRE) and the orbit-only SISRE are analyzed to assess the accuracy of BDS broadcast ephemeris. Due to the upgrade of BDS-3 satellite hardware technology and inter-satellite links payload and the development of satellite orbit determination algorithm, the accuracy of broadcast orbit and clock offsets has been greatly improved. The root mean square (RMS) of BDS-3 broadcast orbit errors is improved by 86.30%, 89.47% and 76.86%, and the standard deviation (STD) is improved by 79.41%, 77.00% and 76.78% compared with BDS-2 in the radial, along-track and cross-track directions. The corresponding RMS and STD of all BDS-3 satellite clock offsets are improved by 40.34% and 52.49% than that of BDS-2, respectively. Meanwhile, the mean RMS and STD are 1.78 m and 0.40 m for BDS-2 SISRE, 1.72 m and 0.34 m for BDS-2 orbit-only SISRE, 0.50 m and 0.14 m for BDS-3 SISRE, and 0.17 m and 0.04 m for BDS-3 orbit-only SISRE. It is noteworthy that the average broadcast-minus-precise (BMP) clock values of BDS-2 and BDS-3 are inconsistent, which can indirectly prove that the datum of broadcast clock offsets for BDS-2 and BDS-3 are inconsistent. The inconsistency of the datum of satellite clock offsets and receiver hardware delay bias between BDS-2 and BDS-3 will result in the inter-system bias (ISB) on the receiver segment. For JAVAD TRE_3 receivers, the ISB is relatively small and thus can be ignored. However, for the TRIMBLE ALLOY, SEPT POLARX5, CETC-54-GMR-4016, CETC-54-GMR-4011, GNSS-GGR and UB4B0-13478 receivers, estimating ISB can improve the positioning accuracy of single point positioning (SPP) by 20.15%, 19.81% and 12.76% in north, east and up directions, respectively.

scholarly journals Making News, Making the Economy: Technological Changes and Financial Pressures in Brazil

2016 ◽  
Vol 11 (1) ◽  
pp. 77-96 ◽  
Author(s):  
Tomás Undurraga
Keyword(s):  
Real Time ◽  
Science And Technology Studies ◽  
Science And Technology ◽  
Cultural Sociology ◽  
Media Convergence ◽  
Time Service ◽  
Technology Studies ◽  
Financial Pressure ◽  
Journalistic Field ◽  
The Impact

Media convergence and growing financial pressure on the journalistic field have triggered significant changes in newsmaking cultures across the world. This article examines the challenges of media convergence in the newsroom of Valor Econômico, the main economic newspaper in Brazil. In particular, it explores how the introduction in 2013 of Valor Pro, a real time news service oriented to the financial market, changed newsmaking practices at Valor Econômico. The introduction of Valor Pro meant that journalists from the whole newsroom had to report news simultaneously for three platforms: the real time service, the online website and the printed paper. This shift not only intensified journalists’ workloads and altered the manufacture of news, but also increased financial pressure on the paper’s agenda. I argue that this shift – from producing news for the public towards producing news for the market – cannot be explained solely with reference to traditional political economic factors such as ideological decisions at editorial level and the structural properties of the Brazilian media sphere. Instead, drawing on resources from cultural sociology and from science and technology studies, I provide a richer explanation that acknowledges the impact of technological innovation, the shifting nature of news values, and the agency of journalists themselves. This article elaborates on seven months of ethnographic fieldwork in Valor Econômico’s newsroom in São Paulo between 2013 and 2015 and contributes to the literature on cultural sociology, media studies and science and technology studies.

scholarly journals Evaluating the impact of CNES real-time ionospheric products on multi-GNSS single-frequency positioning using the IGS real-time service

2020 ◽  
Vol 66 (11) ◽  
pp. 2516-2527
Author(s):  
Ahao Wang ◽  
Junping Chen ◽  
Yize Zhang ◽  
Lingdong Meng ◽  
Binghao Wang ◽  
...  
Keyword(s):  
Real Time ◽  
Single Frequency ◽  
Time Service ◽  
The Impact

scholarly journals An Enhanced Real-Time Regional Ionospheric Model Using IGS Real-Time Service (IGS-RTS) Products

2015 ◽  
Vol 69 (3) ◽  
pp. 521-530 ◽  
Author(s):  
Mohamed Abdelazeem ◽  
Rahmi N. Çelik ◽  
Ahmed El-Rabbany
Keyword(s):  
Real Time ◽  
Convergence Time ◽  
Single Frequency ◽  
High Solar Activity ◽  
Satellite Orbits ◽  
Electron Content ◽  
Ionospheric Model ◽  
Time Service ◽  
The Real ◽  
Regional Ionospheric Model

Recently, the International Global Navigation Satellite System (GNSS) Service (IGS) has launched the Real-Time Service (IGS-RTS). The RTS products enable real-time precise positioning applications. For single-frequency Real-Time Precise Point Positioning (RT-PPP), ionospheric delay mitigation is a major challenge. To overcome this challenge, we developed a Real-Time Regional Ionospheric Model (RT-RIM) over Europe using the RTS satellite orbits and clock products. The model has spatial and temporal resolution of 1° × 1° and 15 minutes, respectively. Global Positioning System (GPS) observations from 60 IGS and EUREF reference stations are processed using the Bernese 5·2 PPP module in order to extract the Real-Time Vertical Electron Content (RT-VTEC). The PPP convergence time and positioning accuracy using the RTS products is estimated and compared with dual frequency PPP and single-frequency PPP obtained through the combined rapid IGS Global Ionospheric Maps (IGS-GIM) over three consecutive days under high solar activity and one of them under active geomagnetic activity. The results show that the proposed model improves PPP accuracy and convergence time under the mid-latitude region about 40%, 55% and 40% for the horizontal, height and three-dimensional (3D) components respectively in comparison with the IGS-GIM.

The impact of real-time continuous glucose monitoring on metabolic control in children with type 1 diabetes

2020 ◽  
Author(s):  
Ruxandra Calapod Ioana ◽  
Irina Bojoga ◽  
Duta Simona Gabriela ◽  
Ana-Maria Stancu ◽  
Amalia Arhire ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Real Time ◽  
Metabolic Control ◽  
Continuous Glucose Monitoring ◽  
Glucose Monitoring ◽  
The Impact
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