Filters








2,492 Hits in 8.2 sec

A Theoretical and Empirical Integrated Method to Select the Optimal Combined Signals for Geometry-Free and Geometry-Based Three-Carrier Ambiguity Resolution

Dongsheng Zhao, Gethin Roberts, Lawrence Lau, Craig Hancock, Ruibin Bai
2016 Sensors  
Please see the repository url above for details on accessing the published version and note that access may require a subscription.  ...  The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version.  ...  Conclusions In this paper, we proposed a theoretical and empirical combined method to select the optimal combined signals for GF TCAR and GB TCAR separately.  ... 
doi:10.3390/s16111929 pmid:27854324 pmcid:PMC5134588 fatcat:n5sihdib7zea5gwqnys45lvzwy

Performance Analysis of GPS/BDS Dual/Triple-Frequency Network RTK in Urban Areas: A Case Study in Hong Kong

Ying Xu, Wu Chen
2018 Sensors  
Based on this platform, the performance of NRTK in urban areas was examined through a series of experiments.  ...  To address these problems and analyze the performance of GPS/BDS dual/triple-frequency NRTK in urban areas, we developed a new Hong Kong GNSS Network RTK Service Platform.  ...  Conflicts of Interest: The authors declare no conflict of interest.  ... 
doi:10.3390/s18082437 pmid:30050021 fatcat:5jns7lhn5rc2tjq5gnsk66ciz4

Integrity Monitoring for Carrier Phase Ambiguities

Shaojun Feng, Washington Ochieng, Jaron Samson, Michel Tossaint, Manuel Hernandez-Pajares, J. Miguel Juan, Jaume Sanz, Àngela Aragón-Àngel, Pere Ramos-Bosch, Marti Jofre
2011 Journal of navigation  
There are a number of current methods for resolving ambiguities including the Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) method, which is a combination of least-squares and a transformation  ...  Specifically, this is determined as a function of geometry and the ambiguity residuals from least squares based ambiguity resolution algorithms including LAMBDA.  ...  The authors would like to thank Simon Johns at the European Navigation Laboratory (ENL), ESTEC ESA for helping to carry out the simulation test during the last week of August 2009.  ... 
doi:10.1017/s037346331100052x fatcat:hfys2se6d5dp7b6jaujcfexfm4

Real-Time Relative Positioning of Spacecraft over Long Baselines

Urbano Tancredi, Alfredo Renga, Michele Grassi
2014 Journal of Guidance Control and Dynamics  
These integer solutions are then used to compute the relative positions with a single-epoch kinematic least square algorithm that processes ionospheric-free combinations of de-biased carrier-phase measurements  ...  To overcome this problem, an original approach is proposed, combining an extended Kalman filter with an integer least square estimator in a closed-loop scheme, capable of fast on-the-fly integer ambiguities  ...  The theoretical assumptions upon which the LAMBDA method and the integer validation tests are based do not hold in these applications.  ... 
doi:10.2514/1.61950 fatcat:b6ohfacwcnbmlej62bcyvxckoa

Carrier phase ambiguity resolution for the Global Positioning System applied to geodetic baselines up to 2000 km

Geoffrey Blewitt
1989 Journal of Geophysical Research  
This paper emphasizes a method for resolving the carrier phase ambiguities which is insensitive to the ionosphere [Melbourne, 1985; W•bbena, 1985] and which is applied to baselines up to 2000 km in length  ...  Dong and Book [1989] have demonstrated ambiguity resolution for baseline lengths up to a few hundred kilometers.  ...  The user can run A_K4BIGON in either a bias fixing or bias optimizing mode, and batches of stations can be selected for ambiguity resolution.  ... 
doi:10.1029/jb094ib08p10187 fatcat:oird7nuq7jbyxcbwmsckodby7m

Geometrically constrained kinematic global navigation satellite systems positioning: Implementation and performance

Jamal Asgari, Tannaz H. Mohammadloo, Ali Reza Amiri-Simkooei
2015 Advances in Space Research  
This has been verified based on the results obtained from the covariance matrix of the estimated parameters and the empirical results using kinematic positioning samples as well.  ...  To enhance the precision, accuracy, reliability and integrity of the estimated unknown parameters, GNSS kinematic equations are to be augmented by possible constraints.  ...  r j Þ kr k À r j k ð3Þ There is another difference between the geometry-free and the geometry-based models.  ... 
doi:10.1016/j.asr.2015.06.022 fatcat:isf7rxcu3fcnharbl4ecu3c7ga

Multiplatform Instantaneous GNSS Ambiguity Resolution for Triple- and Quadruple-Antenna Configurations with Constraints

Peter J. Buist, Peter J. G. Teunissen, Gabriele Giorgi, Sandra Verhagen
2009 International Journal of Navigation and Observation  
The methods developed are rigorous and have the additional advantage that they improve ambiguity resolution on the unconstrained baseline(s) and the overall success rate of ambiguity resolution between  ...  In this contribution we will investigate the possibilities of using multiantenna (i.e., triple and quadruple) data, not only for attitude determination but also for relative positioning.  ...  Acknowledgments Part of this work was done by Peter Buist at JAXA-ISAS, Japan, during a research visit with Professor Tatsuaki Hashimoto and the support of his group is acknowledged.  ... 
doi:10.1155/2009/565426 fatcat:4ownweoidncfdazxne5y6bvuoe

The physics of solid-state neutron detector materials and geometries

A N Caruso
2010 Journal of Physics: Condensed Matter  
Clever indirect-conversion geometries, interaction/transport calculations and modern processing methods for silicon and gallium arsenide allow for the realization of moderate-to high-efficiency neutron  ...  This review focuses on advances and challenges in charged-particle-based device geometries, materials and associated mechanisms for direct and indirect transduction of thermal to fast neutrons within the  ...  Ultimately, this method is interesting theoretically, but may fundamentally yield too low a resolution relative to the third method discussed above and will likely remain limited to detectors whose primary  ... 
doi:10.1088/0953-8984/22/44/443201 pmid:21403341 fatcat:dlml735rujf5npflyglqh442qm

Cycle Slip Detection during High Ionospheric Activities Based on Combined Triple-Frequency GNSS Signals

Dongsheng Zhao, Craig Hancock, Gethin Roberts, Shuanggen Jin
2019 Remote Sensing  
The measurement noise in the Hatch–Melbourne–Wübbena combination is minimized by employing the optimally selected combined signals, while the ionospheric delay is detrended using a smoothing technique.  ...  The difference between the time-differenced ambiguity of the combined signal and this estimated ionospheric trend is adopted as the detection value, which can be free from ionospheric effect and hold the  ...  Acknowledgments: The authors gratefully acknowledge the International GNSS Service, German Research Centre for Geosciences for providing GNSS products, GNSS data and Kp index value.  ... 
doi:10.3390/rs11030250 fatcat:xkvj4szicfgidgtwsckk7n4ouu

Ionospheric delays compensation for on-the-fly integer ambiguity resolution in long baseline LEO formations

Urbano Tancredi, Alfredo Renga, Michele Grassi
2014 International Journal of Space Science and Engineering  
The first formulation models differential ionospheric delays as a function of the vertical total electron content above the receivers, whereas the second one is based on combining the DD measurements for  ...  On long baselines, high accuracy can be achieved only using dual-frequency measurements and exploiting the integer nature of Double Difference (DD) carrier-phase ambiguities.  ...  The ionospheric-free combination (IF) is the most natural and diffuse combination for eliminating the ionospheric delay and it is based on combining observations of the same type on two carrier frequencies  ... 
doi:10.1504/ijspacese.2014.060107 fatcat:a7kifvrlknbk7d4aosoq4dt2ii

Empirical Stochastic Model of Multi-GNSS Measurements

Dominik Prochniewicz, Kinga Wezka, Joanna Kozuchowska
2021 Sensors  
the carrier-phase ambiguity resolution (AR).  ...  The aim of this work is to develop an individual, empirical stochastic model for each signal and each satellite block for GPS, GLONASS, Galileo and BeiDou systems.  ...  was examined based on the relative carrier-phase model for a very short baseline and Kalman Filter estimation method.  ... 
doi:10.3390/s21134566 fatcat:7gi7j6xycrb2zjn7mpm73bfjga

A KALMAN FILTER SINGLE POINT POSITIONING FOR MARITIME APPLICATIONS USING A SMARTPHONE

Anna INNAC, Antonio ANGRISANO, Gino DARDANELLI, Vincenzo DELLA CORTE, Elena MARTELLATO, Alessandra ROTUNDI, Giampaolo FERRAIOLI, Pasquale PALUMBO, Salvatore GAGLIONE
2020 Geographia Technica  
In addition, different GNSSs configurations are considered to verify the benefits of their integration in terms of accuracy, solution availability and geometry.  ...  The algorithm performance evaluation is carried out in position domain and the results show an enhancement of meter order on vertical component compared to the classical SPP based on Least Square estimation  ...  Both RTK and PPP exploits the carrier-phase measurements, that are highly precise observations but very sensitive to signal obstruction and affected by an ambiguity which is unknown to the user and that  ... 
doi:10.21163/gt_2021.163.02 fatcat:sp4rp7jnhvgrjlxiicpa2aqbvi

Fixed point theorems of GPS carrier phase ambiguity resolution and their application to massive network processing: Ambizap

Geoffrey Blewitt
2008 Journal of Geophysical Research  
The narrow lane method is based on ionosphere-free observations, with bootstrapping applied to all satellites observed by both stations, such that resolution of the best determined ambiguities improves  ...  Baseline Selection [36] The following steps now describe how baselines are selected, given the possibility of ambiguity resolution failure, based on concepts of section 2.5.  ... 
doi:10.1029/2008jb005736 fatcat:fqg6chln4bf6nmlangbifhhwo4

Mapping quality prediction for RTK/PPK-equipped micro-drones operating in complex natural environment

E. Cledat, L.V. Jospin, D.A. Cucci, J. Skaloud
2020 ISPRS journal of photogrammetry and remote sensing (Print)  
Drone mapping with GNSS-assisted photogrammetry is a highly efficient method for surveying small-or medium-sized areas.  ...  We present a method to predict the mapping quality from the information that is available prior to the flight, such as the flight plan, expected flight time, approximate digital terrain model, prevailing  ...  For example, in Piatti and Lerma (2013) , a method was described to simulate the geometry of a photogrammetric survey.  ... 
doi:10.1016/j.isprsjprs.2020.05.015 fatcat:2ghzx2c5yzdvvpdhack2myvwgm

Assessing the Performance of Multi-GNSS PPP-RTK in the Local Area

Hongyang Ma, Qile Zhao, Sandra Verhagen, Dimitrios Psychas, Xianglin Liu
2020 Remote Sensing  
provided to users to help them achieve integer ambiguity resolution on a single receiver by calibrating the satellite phase biases.  ...  For instance, the convergence time of GPS alone ambiguity fixed solutions to achieve 10 cm three-dimensional (3D) positioning accuracy is 39.5 min, while it is 37 min for GPS + Galileo ambiguity float  ...  Acknowledgments: The authors would like to thank Kadaster for maintaining the Netherlands GNSS network.  ... 
doi:10.3390/rs12203343 fatcat:ytmqvzh5yfdnxm7izp7jwykngq
« Previous Showing results 1 — 15 out of 2,492 results