scholarly journals Improved Multi-GNSS PPP Software for Upgrading the DEMETRA Project Time Monitoring Service

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4389 ◽  
Author(s):  
Wei Huang ◽  
Pascale Defraigne ◽  
Giovanna Signorile ◽  
Ilaria Sesia
Keyword(s):  
Global Positioning System ◽  
Integer Ambiguity ◽  
Noisy Environments ◽  
Long Term Stability ◽  
Royal Observatory ◽  
Global Positioning ◽  
Receiver Clock ◽  
Frequency Transfer ◽  
Monitoring Service

The H2020 DEMETRA project provides short latency clock monitoring services to the time users using the Atomium precise point positioning (PPP) software developed by the Royal Observatory of Belgium. In this paper, three recent updates of the current Atomium software are introduced: adding Galileo signals in the PPP computation; the option to constrain the receiver clock; PPP with integer ambiguity resolution. The advantages of these updates are demonstrated: Combining the Galileo and global positioning system (GPS) signals for PPP time transfer will further improve the frequency stability inside the computation batch; PPP with receiver clock constraint is not only used to reduce the short-term noise of the clock measurements but can also be used for some specific applications to a keep continuous clock solution in the computation batch or retrieve correct clock measurements from extremely noisy environments; the integer PPP allows a continuous clock solution, and improves the mid-term and long-term stability of the frequency transfer compared to the current PPP frequency transfer techniques.

scholarly journals 1996–2017 GPS position time series, velocities and quality measures for the CORS Network

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jarir Saleh ◽  
Sungpil Yoon ◽  
Kevin Choi ◽  
Lijuan Sun ◽  
Richard Snay ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Term Stability ◽  
Long Term Stability ◽  
Velocity Models ◽  
Daily Data ◽  
The Us ◽  
Global Positioning ◽  
Position Time Series ◽  
Better Than

Abstract The CORS network is a volunteer-based network of Global Positioning System reference stations located mainly in the US and its territories. We discuss the most recent comprehensive reprocessing of all GPS data collected via this network since 1996. Daily data for GPS weeks 834 through 1933 were reprocessed leading to epoch 2010.0 coordinates and velocities of 3049 stations aligned to IGS14. The updated realization of the US National Spatial Reference System derived in this work has been in use since late 2019. As a validation of the results, the derived velocity field is compared to several other solutions and to three regional geophysical and geodetic velocity models. These comparisons uncovered unstable stations which move differently than the regional kinematics around them. Once these are ignored, we estimate the horizontal and vertical stability of this updated realization to be better than ∼0.3 and ∼0.6 mm/year, respectively. We use the position residuals and estimated uncertainties from this reprocessing to derive long-term stability measures for all active stations serving longer than 3 years. These measures exposed ∼60 CORS with the poorest long-term stability, which have been consequently excluded from serving as mapping control.

scholarly journals Analyzing Road Coverage of Public Vehicles According to Number and Time Period for Installation of Road Inspection Systems

2020 ◽  
Vol 9 (3) ◽  
pp. 161 ◽  
Author(s):  
Takehiro Kashiyama ◽  
Yoshihide Sekimoto ◽  
Toshikazu Seto ◽  
Ko Ko Lwin
Keyword(s):  
Global Positioning System ◽  
Local Governments ◽  
Inspection System ◽  
Positioning System ◽  
Efficient Operation ◽  
Time Period ◽  
Global Positioning ◽  
Inspection Systems ◽  
Road Inspection

Shortages of engineers and financial resources have made it difficult for municipalities to identify and address problems with aging road infrastructures. To resolve these problems, numerous studies have focused on automating road inspection, including a study in which we developed a smartphone-based road inspection system. For efficient operation of the system, it is necessary to understand the usage of vehicles in which the system will be installed. In this study, we analyzed the usage of public vehicles with long-term global positioning system (GPS) probe data collected from public vehicles operating in Kakogawa city and Fujisawa city in Japan. As a result, we discovered that local governments of the same size have similar tendencies in terms of road coverage. Moreover, we found that installing road inspection systems on only a few public vehicles can cover the entire road inspection area. We anticipate that these results will assist local governments in making informed decisions during the system introduction process and provide an indicator of the accuracy required for road inspection systems to future researchers.

Determination of global positioning system (GPS) receiver clock errors: impact on positioning accuracy

2009 ◽  
Vol 20 (7) ◽  
pp. 075105 ◽  
Author(s):  
Ta-Kang Yeh ◽  
Cheinway Hwang ◽  
Guochang Xu ◽  
Chuan-Sheng Wang ◽  
Chien-Chih Lee
Keyword(s):  
Global Positioning System ◽  
Positioning System ◽  
Gps Receiver ◽  
Positioning Accuracy ◽  
Global Positioning ◽  
Receiver Clock

scholarly journals Detection and elimination method for deception jamming based on an antenna array

2018 ◽  
Vol 14 (5) ◽  
pp. 155014771877446 ◽  
Author(s):  
Shuyan Ni ◽  
Jianhua Cui ◽  
Naiping Cheng ◽  
Yurong Liao
Keyword(s):  
Global Positioning System ◽  
Measurement Errors ◽  
Integer Ambiguity ◽  
Double Difference ◽  
Fast Method ◽  
Short Baseline ◽  
Elimination Method ◽  
Medium Length ◽  
Global Positioning ◽  
Jamming Detection

A global positioning system is an important way of locating an aircraft, while deception jamming can affect the positioning accuracy of such navigation. Considering this, a detection and elimination method for deception jamming is proposed based on a specially designed array for the aircraft. The jamming is detected by comparing the double-difference observation of the carrier phases of two different signals to a certain threshold derived according to the measurement errors of the receiver. To estimate the jamming direction with high accuracy, meanwhile considering the feasibility of airborne installation, a novel configurated array combining medium-length baseline with short baseline is designed, and a fast method to solve the integer ambiguity is discussed. After jamming detection, the nulling of the array beam is pointed to the jamming source through the orthogonal vector weighting to suppress jamming. The validity of the method is verified by computer simulations.

scholarly journals Characterization of the Long-term Radiosonde Temperature Biases in the Lower Stratosphere using COSMIC and Metop-A/GRAS Data from 2006 to 2014

2016 ◽  
Author(s):  
Shu-Peng Ho ◽  
Liang Peng ◽  
Holger Vömel
Keyword(s):  
Global Positioning System ◽  
Lower Stratosphere ◽  
Temperature Measurements ◽  
Global Trend ◽  
Global Positioning ◽  
The Mean ◽  
Geographical Locations

Abstract. Radiosonde observations (RAOBs) have provided the only long-term global in situ temperature measurements in the troposphere and lower stratosphere since 1958. In this study, we use consistently reprocessed Global Positioning System (GPS) radio occultation (RO) temperature data derived from COSMIC and Metop-A/GRAS missions from 2006 to 2014 to characterize the inter-seasonal and inter-annual variability of temperature biases in the lower stratosphere for different sensor types. The results show that the RAOB temperature biases for different RAOB sensor types are mainly owing to i) uncorrected solar zenith angle dependent errors, and ii) change of radiation correction. The mean daytime temperature difference (ΔT) for Vaisala RS92 is equal to 0.18 K in Australia, 0.20 K in Germany, 0.10 K in Canada, 0.13 K in England, and 0.33 K in Brazil. The mean daytime ΔT is equal to −0.06 K for Sippican, 0.71 K for VIZ-B2, 0.66 K for AVK-MRZ, and 0.18 K for Shanghai. The daytime trend of anomalies for Vaisala RS92 and RO temperature at 50 hPa is equal to 0.00 K/5 yrs over United States, −0.02 K/5 yrs over Germany, 0.17 K/5 yrs over Australia, 0.23 K/5 yrs over Canada, 0.26 K/5 yrs over England, and 0.12 K/5 yrs over Brazil, respectively. Although there still exist uncertainties for Vaisala RS92 temperature measurements over different geographical locations, the global trend of temperature anomaly between Vaisala RS92 and RO from June 2006 to April 2014 is within +/−0.09 K/5 yrs globally. Comparing with Vaisala RS80, Vaisala RS90 and sondes from other manufacturers, the Vaisala RS92 seems to provide the best RAOB temperature measurements, which can potentially be used to construct long term temperature CDRs. Results from this study also demonstrate the feasibility to use RO data to correct RAOB temperature biases for different sensor types.

scholarly journals The Unified Form of Code Biases and Positioning Performance Analysis in Global Positioning System (GPS)/BeiDou Navigation Satellite System (BDS) Precise Point Positioning Using Real Triple-Frequency Data

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2469 ◽  
Author(s):  
Peng Liu ◽  
Honglei Qin ◽  
Li Cong
Keyword(s):  
Global Positioning System ◽  
Precise Point Positioning ◽  
Satellite System ◽  
Navigation Satellite ◽  
Dual Frequency ◽  
Triple Frequency ◽  
Global Positioning ◽  
Receiver Clock ◽  
Point Positioning ◽  
Fixed Solution

Multi- system and multi-frequency are two key factors that determine the performance of precise point positioning. Both multi-frequency and multi-system lead to new biases, which are not solved systematically. This paper concentrates on mathematical models of biases, influences of these biases, and positioning performance analysis of different observation models. The biases comprise the inter-frequency clock bias in multi-frequency and the inter-system clock bias in multi-system. The former is the residual differential code biases (DCBs) from receiver clock and satellite clock and usually occurs at the third frequency, the latter is the deviation of the receiver clock errors in different systems. Unified mathematical models of the biases are presented by analyzing the general formula of observation equations. The influences of these biases are validated by experiments with corresponding observation models. Subsequently, the experiments, which are based on the data at five globally distributed stations in Multi-Global Navigation Satellite System (GNSS) Experiment (MGEX) on day of year 100, 2018, assess positioning performance of different observation models with combination of frequencies (dual-frequency or triple- frequency) and systems (BeiDou Navigation Satellite System (BDS) or Global Positioning System (GPS)). The results show that the performances of triple-frequency models are almost as the same level as the dual-frequency models. They provide scientific support for the triple-frequency ambiguity-fixed solution which has a better convergence characteristic than dual-frequency ambiguity-fixed solution. Furthermore, the biases are expressed as an unified form that gives an important and valuable reference for future research on multi-frequency and multi-system precise point positioning.

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