scholarly journals Divagations on the Appropriate Satellite System from GNSS for Aviation

2021 ◽  
Vol 2021 (1) ◽  
pp. 75-92
Author(s):  
Andrzej Fellner ◽  
Robert Konieczka
Keyword(s):  
Satellite System ◽  
American Military ◽  
Satellite Signal ◽  
Gps System ◽  
Navigation Accuracy

Abstract American military satellite GPS system is an element of the global GNSS. It emits two codes: the precise and civil one. As late as in 2000, intentional interference that decreased precision of localization was introduced, allowing navigation accuracy of 20 m. GPS was made available to civil users, however, at their own responsibility. So, if we use GPS for our own goals, we must consider the errors that occur and their consequences. Nonetheless, commercial and operational needs determine the necessity of permanent access to satellite signal with appropriate consistency, accessibility, reliability and precision. Hence, natural and intentional errors are compensated for, using appropriate methods, based on a given activity.

scholarly journals Absolute Calibration or Validation of the Altimeters on the Sentinel-3A and the Jason-3 over Lake Issykkul (Kyrgyzstan)

2018 ◽  
Vol 10 (11) ◽  
pp. 1679 ◽  
Author(s):  
Jean-François Crétaux ◽  
Muriel Bergé-Nguyen ◽  
Stephane Calmant ◽  
Nurzat Jamangulova ◽  
Rysbek Satylkanov ◽  
...  
Keyword(s):  
Satellite System ◽  
Reference Points ◽  
Absolute Calibration ◽  
In Situ Data ◽  
Absolute Bias ◽  
Weather Stations ◽  
Field Campaigns ◽  
The Absolute ◽  
Gps System ◽  
Water Height

Calibration/Validation (C/V) studies using sites in the oceans have a long history and protocols are well established. Over lakes, C/V allows addressing problems such as the performance of the various retracking algorithms and evaluating the accuracy of the geophysical corrections for continental waters. This is achievable when measurements of specific and numerous field campaigns and a ground permanent network of level gauges and weather stations are processed. C/V consists of installation of permanent sites (weather stations, limnigraphs, and GPS reference points) and the organization of regular field campaigns. The lake Issykkul serves as permanent site of C/V, for a multi-mission purpose. The objective of this paper is to calculate the altimeter biases of Jason-3 and Sentinel-3A, both belonging to an operational satellite system which is used for the long-term monitoring of lake level variations. We have also determined the accuracy of the altimeters of these two satellites, through a comparison analysis with in situ data. In 2016 and 2017, three campaigns have been organized over this lake in order to estimate the absolute bias of the nadir altimeter onboard the Jason-3 and Sentinel-3A. The fieldwork consisted of measuring water height using a GPS system, carried on a boat, along the track of the altimeter satellite across the lake. It was performed at the time of the pass of the altimeter. Absolute altimeter biases were calculated by averaging the water height differences along the pass of the satellite (GPS from the boat system versus altimetry). Jason-3 operates in a Low Resolution Mode (LRM), while the Sentinel-3A operates in Synthetic Aperture Radar (SAR) mode. In this study we found that the absolute biases measured for Jason-3 were −28 ± 40 mm with the Ocean retracker and 206 ± 30 mm with the Ice-1 retracker. The biases for Sentinel-3A were −14 ± 20 mm with the Samosa (Ocean like) retracker and 285 ± 20 mm with the OCOG (Ice-1-like) retracker. We have also evaluated the accuracy of these two altimeters over Lake Issykkul which reached to 3 cm, for both the instruments, using the Ocean retracker.

Studies of the integrated navigation system correction in the absence of a satellite signal

2021 ◽  
Author(s):  
Keyword(s):  
Kalman Filter ◽  
Navigation System ◽  
Operation Mode ◽  
Satellite System ◽  
Navigation Systems ◽  
Integrated Navigation ◽  
Integrated Navigation System ◽  
Correction Signal ◽  
Satellite Signal ◽  
Navigation Information

The schemes of navigation systems correction are considered. The operation mode of the aircraft during navigation is analyzed. An adaptive modification of the linear Kalman filter is used to correct the navigation information. An algorithm for predicting a correction signal based on a neural network in the event of a loss of a SNS correction signal is formed. Experimental results show the effectiveness of the algorithm. Keywords aircraft; inertial navigation system; satellite system; Kalman filter; neural networks; genetic algorithm

Augmentation Systems

2011 ◽  
pp. 283-293
Author(s):  
Mohammad S. Sharawi
Keyword(s):  
Performance Metrics ◽  
Satellite System ◽  
Space Vehicles ◽  
Gps Receivers ◽  
Commercial Use ◽  
Global Positioning ◽  
Almost All ◽  
Gps System ◽  
Year 2000 ◽  
Route Navigation

The global positioning satellite system (GPS) has been utilized for commercial use after the year 2000. Since then, GPS receivers have been integrated for accurate positing of ground as well as space vehicles. Almost all aircrafts nowadays rely on GPS based system for their take off, landing, and en-route navigation. Relying on GPS alone does note provide the meter level accuracy needed to guarantee safe operation of aircrafts. Thus several augmentation systems have been deployed worldwide to enhance the accuracy of the GPS system. Several augmentation systems that serve local as well as wide coverage areas are discussed in this chapter, specifically the LAAS system, the WAAS system as well as the EGNOS system. The architecture as well the performance metrics for each of these augmentation systems are presented and discussed.

scholarly journals A Joint Dual-Frequency GNSS/SINS Deep-Coupled Navigation System for Polar Navigation

2018 ◽  
Vol 8 (11) ◽  
pp. 2322 ◽  
Author(s):  
Lin Zhao ◽  
Mouyan Wu ◽  
Jicheng Ding ◽  
Yingyao Kang
Keyword(s):  
Navigation System ◽  
Density Ratio ◽  
Satellite System ◽  
The Arctic ◽  
Observation Data ◽  
Dual Frequency ◽  
Vector Tracking ◽  
Time Observation ◽  
Global Navigation Satellite ◽  
Navigation Accuracy

The strategic position of the polar area and its rich natural resources are becoming increasingly important, while the northeast and northwest passages through the Arctic are receiving much attention as glaciers continue to melt. The global navigation satellite system (GNSS) can provide real-time observation data for the polar areas, but may suffer low elevation problems of satellites, signals with poor carrier-power-to-noise-density ratio (C/N0), ionospheric scintillations, and dynamic requirements. In order to improve the navigation performance in polar areas, a deep-coupled navigation system with dual-frequency GNSS and a grid strapdown inertial navigation system (SINS) is proposed in the paper. The coverage and visibility of the GNSS constellation in polar areas are briefly reviewed firstly. Then, the joint dual-frequency vector tracking architecture of GNSS is designed with the aid of grid SINS information, which can optimize the tracking band, sharing tracking information to aid weak signal channels with strong signal channels and meet the dynamic requirement to improve the accuracy and robustness of the system. Besides this, the ionosphere-free combination of global positioning system (GPS) L1 C/A and L2 signals is used in the proposed system to further reduce ionospheric influence. Finally, the performance of the system is tested using a hardware simulator and semiphysical experiments. Experimental results indicate that the proposed system can obtain a better navigation accuracy and robust performance in polar areas.

scholarly journals Results of the GNSS receiver experiment OCAM-G on Ariane-5 flight VA 219

2016 ◽  
Vol 231 (6) ◽  
pp. 1100-1114 ◽  
Author(s):  
André Hauschild ◽  
Markus Markgraf ◽  
Oliver Montenbruck ◽  
Horst Pfeuffer ◽  
Elie Dawidowicz ◽  
...  
Keyword(s):  
French Guiana ◽  
Satellite System ◽  
Navigation Satellite ◽  
Navigation Solution ◽  
Gnss Receiver ◽  
Upper Stage ◽  
Lift Off ◽  
Global Navigation Satellite ◽  
Navigation Accuracy ◽  
First Time

The fifth Automated Transfer Vehicle was launched on 29 July 2014 with Ariane-5 flight VA 219 into orbit from Kourou, French Guiana. For the first time, the ascent of an Ariane rocket was independently tracked with a Global Navigation Satellite System (GNSS) receiver on this flight. The GNSS receiver experiment OCAM-G was mounted on the upper stage of the rocket. Its receivers tracked the trajectory of the Ariane-5 from lift-off until after the separation of the Automated Transfer Vehicle. This article introduces the design of the experiment and presents an analysis of the data gathered during the flight with respect to the GNSS tracking status, availability of navigation solution, and navigation accuracy.

scholarly journals GNSS/INS Fusion with Virtual Lever-Arm Measurements

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2228 ◽  
Author(s):  
Aviram Borko ◽  
Itzik Klein ◽  
Gilad Even-Tzur
Keyword(s):  
Field Experiments ◽  
Satellite System ◽  
Improve Performance ◽  
Lever Arm ◽  
Additional Improvement ◽  
Stationary Conditions ◽  
State Observability ◽  
Global Navigation Satellite ◽  
Navigation Accuracy ◽  
Improve State

The navigation subsystem in most platforms is based on an inertial navigation system (INS). Regardless of the INS grade, its navigation solution drifts in time. To avoid such a drift, the INS is fused with external sensor measurements such as a global navigation satellite system (GNSS). Recent publications showed that the lever-arm, defined as the relative position between the INS and aiding sensor, has a strong influence on navigation accuracy. Most research in this field is focused on INS/GNSS fusion with GNSS position or velocity updates while considering various maneuvers types. In this paper, we propose to employ virtual lever-arm (VLA) measurements to improve the accuracy and time to convergence of the observable INS error-states. In particular, we show that VLA measurements improve performance even in stationary conditions. In situations when maneuvering helps to improve state observability, VLA measurements manage to gain additional improvement in accuracy. These results are supported by simulation and field experiments with a vehicle mounted with a GNSS and an INS.

scholarly journals A Method to Improve the Distribution of Observations in GNSS Water Vapor Tomography

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2526 ◽  
Author(s):  
Fei Yang ◽  
Jiming Guo ◽  
Junbo Shi ◽  
Lv Zhou ◽  
Yi Xu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Precipitable Water ◽  
Absolute Error ◽  
Satellite System ◽  
Observation Data ◽  
Radiosonde Station ◽  
Satellite Signal ◽  
Comparative Results ◽  
Global Navigation Satellite ◽  
Vapor Distribution

Water vapor is an important driving factor in the related weather processes in the troposphere, and its temporal-spatial distribution and change are crucial to the formation of cloud and rainfall. Global Navigation Satellite System (GNSS) water vapor tomography, which can reconstruct the water vapor distribution using GNSS observation data, plays an increasingly important role in GNSS meteorology. In this paper, a method to improve the distribution of observations in GNSS water vapor tomography is proposed to overcome the problem of the relatively concentrated distribution of observations, enable satellite signal rays to penetrate more tomographic voxels, and improve the issue of overabundance of zero elements in a tomographic matrix. Numerical results indicate that the accuracy of the water vapor tomography is improved by the proposed method when the slant water vapor calculated by GAMIT is used as a reference. Comparative results of precipitable water vapor (PWV) and water vapor density (WVD) profiles from radiosonde station data indicate that the proposed method is superior to the conventional method in terms of the mean absolute error (MAE), standard deviations (STD), and root-mean-square error (RMS). Further discussion shows that the ill-condition of tomographic equation and the richness of data in the tomographic model need to be discussed separately.

Parallel Frequency Acquisition Algorithm for BeiDou Software Receiver Based on Coherent Downsampling

2019 ◽  
Vol 73 (2) ◽  
pp. 433-454
Author(s):  
Qingxi Zeng ◽  
Chang Gao ◽  
Wenqi Qiu ◽  
Zhaihe Zhou ◽  
Chade Lyu
Keyword(s):  
Signal To Noise Ratio ◽  
Random Noise ◽  
Satellite System ◽  
Frequency Space ◽  
Satellite Signal ◽  
Parallel Code ◽  
Initial Sampling ◽  
Global Navigation Satellite ◽  
Down Conversion ◽  
Band Signal

The time it takes to acquire a satellite signal is one of the most important parameters for a Global Navigation Satellite System (GNSS) receiver. The Parallel Frequency space search acquisition Algorithm (PFA) runs faster than the Parallel Code phase search acquisition Algorithm (PCA) when the approximate phase of Pseudo-Random Noise (PRN) code and the approximate value of a Doppler shift are known. However, a large amount of data is needed to be dealt with by the Fast Fourier Transform (FFT) in a traditional PFA algorithm because it processes a narrow-band signal with the initial sampling frequency after the PRN code is stripped. In order to reduce the computational complexity of the traditional PFA algorithm, a down-conversion module and a downsampling module were added to the traditional PFA in the work reported here. Experiments demonstrated that this method not only succeeded in acquiring BeiDou B1I signals, but also the time for acquirement was reduced by at least 80% with the modified PFA algorithm compared with the traditional PFA algorithm. The loss in Signal-to-Noise Ratio (SNR) did not exceed 0·5 dB when the number of coherent points was less than 500.

The Research of Comprehensive Network Maintenance Management System Based on BDS & GPS

2014 ◽  
Vol 543-547 ◽  
pp. 2858-2861
Author(s):  
Xiao Mei Zhang ◽  
Yuan Cheng ◽  
Bing Qi ◽  
Chen Xiong
Keyword(s):  
Management System ◽  
Satellite System ◽  
Maintenance Management ◽  
System Structure ◽  
Network Systems ◽  
Basic Principles ◽  
Maintenance System ◽  
Network Maintenance ◽  
Security Of Network ◽  
Gps System

According to the existing network maintenance system and the basic principles of composition, this paper provides a terminal system scheme and network maintenance management system based on BeiDou Navigation Satellite System (BDS) compatible with GPS by analyzing the system structure, functional architecture and software architecture. Studies have shown that the BDS compatible with GPS system can manage and monitor personnel and vehicles in real time and improves the reliability and security of network systems.

scholarly journals Single-Epoch Navigation Performance with Real BDS Triple-Frequency Pseudorange and EWL/WL Observations

2016 ◽  
Vol 69 (6) ◽  
pp. 1293-1309 ◽  
Author(s):  
Wang Gao ◽  
Chengfa Gao ◽  
Shuguo Pan
Keyword(s):  
Satellite System ◽  
Asia Pacific ◽  
Free Form ◽  
Asia Pacific Region ◽  
Frequency Signal ◽  
Beidou Navigation Satellite System ◽  
Triple Frequency ◽  
Wide Lane ◽  
Single Epoch ◽  
Navigation Accuracy

Triple-frequency signals of China's BeiDou navigation satellite system (BDS) are now accessible in the Asia-Pacific region. It is well understood that the third frequency signal will improve the navigation performance. Some literatures have described several navigation methods by using triple-frequency signals, and evaluated the performance. However the experiments were mostly implemented on simulated or semi-simulated observations. In this paper we investigate the navigation performance using real BDS triple-frequency observations. Apart from the pseudorange observations, carrier observations are also used, since the extra-wide-lane and wide-lane ambiguities can be reliably resolved with a single epoch. Several single-epoch navigation methods using BDS triple-frequency observations are described and the corresponding navigation accuracy and reliability are assessed. Results show that P3 has the highest accuracy among the three pseudorange observations. For carriers, the wide-lane and extra-wide-lane observations can be used to obtain much higher navigation precision compared with pseudorange observations. Besides, the two ambiguity-fixed extra-wide-lane and wide-lane observations can also be combined to ionosphere-free form, which can still obtain sub-decimetre and decimetre navigation accuracy in horizontal and vertical directions respectively.

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