GNSS augmentation

About: GNSS augmentation is a research topic. Over the lifetime, 2478 publications have been published within this topic receiving 28513 citations. The topic is also known as: SBAS & Satellite Based Augmentation System.

Validating InSAR-SBAS results by means of different GNSS analysis techniques in medium- and high-grade deformation areas

Abstract: This study aimed to validate the interferometric synthetic aperture radar (InSAR) method by using relative and absolute Global Navigation Satellite System (GNSS) techniques. In this context, two land subsidence areas, one high (Mexico City) and one medium (Aguascalientes), were monitored between 2014 and 2018 by using Sentinel 1A satellite data. The monitoring was carried out with the Small Baseline Subset (SBAS) technique using 46 images for Mexico City and 18 images for Aguascalientes. Concordantly, the GNSS Continuously Operating Reference Station (CORS) data in the regions were analyzed with relative and Precise Point Positioning (PPP) GNSS analysis techniques. The time series obtained from three different analyses were compared and the results were evaluated in light of statistical criteria. According to the results, it is determined that the InSAR-SBAS technique can vary up to ± 20 mm from the displacement values obtained from GNSS due to various noise sources. Such deviations were limited to a few samples, and in general the differentiations were reasonable in the range of 7–8 mm. The difference between the deformation velocity estimation results obtained from the three different methods varied between 3 and 10 mm/year. In this context, these findings suggest that the InSAR-SBAS technique is an effective method for monitoring land deformation with the accuracy of sub-centimeter decided. In addition, PPP which has become an increasingly popular technique showed fast and reliable results in the range of 5–10 mm for InSAR verification. Moreover, with this study, most current results for Mexico City, which is the world’s fastest subsiding metropole, were achieved. In the central region of the city, the detected 300 mm/year of subsidence rate was updated as 370 mm/year. In addition, Aguascalientes was monitored by using the Sentinel 1A satellite mission for the first time in this study. The 60 mm/year subsidence rate obtained for Aguascalientes in previous studies was updated and it was estimated that there are zones where this rate reaches up to − 115 mm/year levels. In this regard, it was concluded that the deformation rate has increased for both regions since the previous monitoring studies.

Satellite selection algorithm for combined GPS-Galileo navigation receiver

Abstract: In the future, integrated GPS-Galileo Navigation Satellite System will expand its applications in many fields. For space robots, it will provide high accuracy and real-time navigation service. As it is well-known, the integrated system will provide twice and more satellites than individual system. Therefore, selecting appropriate satellites from the combined constellation is a very important aspect. Using a reasonable and fast algorithm to select satellites would have a favor to precise and real-time navigation. Integrated GPS-Galileo is a mixed-constellation navigation system consisting of satellites of two different types. Taking the different satellites have different range errors into account, we choose the Weighted Geometric Dilution of Precision (WGDOP) instead of Geometric Dilution of Precision (GDOP) as the optimal satellite selection criteria and propose the new satellite selection criteria-WGDOP minimum algorithm for the combined GPS-Galileo navigation receiver. The algorithm makes full use of available information to select the optimal satellites for navigation solution. And the selection algorithm is simulated and validated by a software simulation. The results show that the WGDOP minimum criteria can more accurately reflect the performance of combined constellation and evaluate the positioning accuracy. And also it can improve the navigation accuracy and reduce the measurement error.

The Ionospheric Impact of the October 2003 Storm Event on WAAS

Abstract: The United States Federal Aviation Administration's (FAA) Wide Area Augmentation System (WAAS) for civil aircraft navigation is focused primarily on the Conterminous United States (CONUS). Other Satellite- Based Augmentation Systems (SBAS) include the European Geostationary Navigation Overlay Service (EGNOS) and the Japanese Global Navigation Satellite System (MSAS). Navigation using WAAS requires accurate calibration of ionospheric delays. to provide delay corrections for single frequency GPS users, the wide area differential GPS systems depend upon accurate determination of ionospheric total electron content (TEC) along radio links. Dual frequency transmissions from GPS satellites have been used for many years to measure and map ionospheric TEX on regional and global scales.

Satellite Network Design Approach to Orbit Determination for GNSS

Abstract: This research work gives the brief knowledge of the orbit determination for Global Navigation Satellite System (GNSS), which described the result of some techniques for orbit determination. In this we have also discussed that how we can design a network for orbit determination of GNSS. The main approach that need to be solved by researchers to monitor the data processing and developing procedures for digital signal processing in micro and onboard satellite navigation equipment have been described. In this paper discussed that how we transfer the data information through the satellite laser link and satellite radio frequency links. After that we analyze that how the data can be transfer between two satellites by considering the epidemic model.

Doppler Frequency Estimation in GNSS Receivers Based on Double FFT

Abstract: This paper presents an innovative Doppler frequency estimation technique, which is particularly suited for global navigation satellite system (GNSS) receivers operating in vehicular scenarios. Mass-market and commercial navigation devices are being increasingly exploited for in-car navigation and for vehicular applications based on positioning. However, the low computational burden that can be afforded by such devices requires the implementation of low-complexity algorithms, allowing real-time and on-demand processing. This is the case, for instance, for open-loop architectures and of maximum likelihood estimation (MLE)-based techniques, which estimate the frequency component of the GNSS signal through a discrete Fourier transform. A state of the art of such methods is first carried out, outlining their benefits, regarding robustness and stability, and their limitations, mainly concerning the accuracy. Successively, an innovative refinement technique is introduced, based on the computation of a frequency correction term. Further enhancements are then proposed to solve particular issues, such as the estimation of the sign of the correction term and the impact of the initial frequency error. In particular, zero forcing and a double fast Fourier transform (FFT), which represent the main contribution of this paper, are proposed to increase the accuracy without increasing the computational load. A complete analytical derivation and theoretical description is provided, along with a detailed performance assessment. Finally, a performance comparison with existing techniques and with the Cramer–Rao lower bound (CRLB) for frequency estimation is given, confirming the excellent behavior of the proposed algorithm for the signal conditions and strengths that are typical of a vehicular scenario and in the presence of frequent interruptions.