Cloud-based near real-time sea level monitoring using GNSS reflectometry
In addition to traditional tide gauges, the ground-based global navigation satellite system reflectometry (GNSS-R) that utilizes signal-to-noise ratio data from a single GNSS receiver has become another promising alternative for sea level ...
Integrity monitoring scheme for undifferenced and uncombined multi-frequency multi-constellation PPP-RTK
The precise point positioning (PPP)-based real-time-kinematic (RTK) method attracts increasing attention from both academia and industry because of its potential for high accuracy positioning with a shorter convergence time compared to the ...
A unified cycle-slip, multipath estimation, detection and mitigation method for VIO-aided PPP in urban environments
Accurate, continuous and reliable positioning is required in autonomous driving. The precise point positioning (PPP) technique, which can provide a global accurate positioning service using a single global navigation satellite system (GNSS) ...
Random walk multipath method for Galileo real-time phase multipath mitigation
Since the orbit repeat cycle of Galileo satellites is about 10 days, existing spatial–temporal repeatability-based station multipath mitigation methods such as the modified sidereal filtering (MSF) and the multipath hemispherical map need more ...
Open-source software for multi-GNSS inter-frequency clock bias estimation
As one of the key issues in multi-frequency Global Navigation Satellite System (GNSS) applications, the inter-frequency clock bias (IFCB) has been well studied in recent years. However, the lack of publicly available IFCB products prevents users ...
Performance of the local ionospheric model in resolving GPS baseline ambiguity over the Malaysian region
The positioning and navigation accuracy of the Global Positioning System (GPS) is highly affected by ionospheric conditions, especially in the Malaysian region, which is located over the equator, where there are several ionospheric irregularities. ...
GDDS: Python software for GNSS data download
With the rapid development of global navigation satellite system (GNSS), GNSS data products have been widely used for high-precision positioning and navigation applications. They are typically downloaded from the international GNSS service (IGS) ...
An adaptive-degree layered function-based method to GNSS tropospheric tomography
Global Navigation Satellite System (GNSS) tropospheric tomography is a promising technique to provide high-resolution three-dimensional (3D) water vapor fields for assimilation into weather forecast models. Recently, a novel tomography method ...
An investigation of PPP time transfer via BDS-3 PPP-B2b service
Since 2020, China's Beidou has begun to provide an initial real-time precise point positioning (PPP) service via B2b signals for the Asia–Pacific region. It is expected to be used to achieve centimeter-level positioning and also brings ...
Assessment of the orbital variations of GNSS GEO and IGSO satellites for monitoring ionospheric TEC
- Zhiyao Li,
- Jiahao Zhong,
- Yongqiang Hao,
- Meng Zhang,
- Jiemin Niu,
- Xin Wan,
- Fuqing Huang,
- Hao Han,
- Xingyan Song,
- Jiawen Chen
The geostationary orbit (GEO) satellites provide a great opportunity to continuously monitor the earth system, which has shown a powerful application in ionospheric total electron content (TEC) studies. As the GEO satellites revolve the earth over ...
Satellite visibility analysis considering signal attenuation by trees using airborne laser scanning point cloud
The number of visible global navigation satellite system (GNSS) satellites is an important indicator for evaluating positioning accuracy. In urban areas, buildings and trees cause serious satellite signal obstruction and attenuation. Studies have ...
Correcting antenna phase center effects to reconcile the code/phase bias products from the third IGS reprocessing campaign
The International GNSS Service aims to provide combined satellite clock and code/phase bias products in the recent third reprocessing campaign (Repro3) to enable more robust ambiguity resolution in precise point positioning (PPP-AR). However, the ...
LSTM-based short-term ionospheric TEC forecast model and positioning accuracy analysis
Ionospheric delay is one of the major error sources in global navigation satellite system (GNSS). The ionospheric delay can be corrected by empirical models, which, however, are limited by the low accuracy. The single-point time-series-based ...
ARAIM based on fault detector reuse for reducing computational load
Since Advanced Receiver Autonomous Integrity Monitoring (ARAIM) evaluates monitored subsets of visible satellites to validate the integrity of position solutions, the increased number and conservative fault probabilities of satellites have ...
Overbounding residual zenith tropospheric delays to enhance GNSS integrity monitoring
Tropospheric delay is one of the main error sources that should be considered in global navigation satellite system (GNSS) positioning and integrity monitoring. Usually, it is first corrected by an empirical tropospheric zenith total delay (ZTD) ...
Long-term performance analysis of BDS-3 precise point positioning (PPP-B2b) service
Since 2020, the BeiDou Navigation Satellite System (BDS) has launched new precise point positioning service which provides precise correction of GPS and BDS-3 satellites to help users realize real-time precise point positioning, known as PPP-B2b ...
Assessment of Galileo High Accuracy Service (HAS) test signals and preliminary positioning performance
The Galileo High Accuracy Service (HAS) is a GNSS augmentation that provides precise satellite corrections to users worldwide for free directly through Galileo’s E6 signal. The HAS service provides free PPP corrections from the Galileo ...
GNSS Site unmodeled error prediction based on machine learning
A number of studies have attempted to reduce the effect of observation errors on Global Navigation Satellite Systems positioning through empirical error models. However, due to the complex spatiotemporal characteristics of observation errors, the ...
An integrated INS/GNSS system with an attention-based hierarchical LSTM during GNSS outage
Navigating drones and estimating their future states for a prolonged duration are challenging without the Global Navigation Satellite System (GNSS) network. Our study proposes an Attention-based Hierarchical Long Short-Term Memory (AHLSTM) model ...
Forecasting of global ionospheric TEC using a deep learning approach
There is a great interest in total electron content (TEC) forecasting. In this study, pix2pixhd, a novel deep learning method based on generative adversarial network, is applied to forecast the global TEC. Different from previous research, similar ...
Assessment of storm-time ionospheric electron density measurements from Spire Global CubeSat GNSS radio occultation constellation
Spire Global’s CubeSats has been collecting global navigation satellite system ionospheric radio occultation (RO) measurements since November 2019. This study presents a comprehensive evaluation of storm-time ionospheric electron density ...
A study on the quality of GNSS signals for extracting the sea level height and tidal frequencies utilizing the GNSS-IR approach
Coastal global navigation satellite system (GNSS) stations equipped with a standard geodetic receiver and antenna enable water level measurement using the GNSS interferometry reflectometry (GNSS-IR) technique. By using GNSS-IR, the vertical ...
Two modified multi-frequency GNSS approaches to estimate the pseudorange observable-specific signal bias for the CDMA and FDMA models
Pseudorange bias handling is essential in satellite positioning, navigation and timing (PNT) services and ionospheric modeling. Differential code bias (DCB) is commonly utilized and parameterized as the differential form of the pseudorange bias. ...
Extracting ionospheric phase scintillation indicator from GNSS observations with 30-s sampling interval in the high-latitude region
- Dongsheng Zhao,
- Xueli Zhang,
- Wang Li,
- Qianxin Wang,
- Craig M. Hancock,
- Chendong Li,
- Gethin Wyn Roberts,
- Kefei Zhang
Ionospheric scintillation affects the positioning, navigation and timing services of the Global Navigation Satellite System (GNSS), calling for an urgent need for scintillation monitoring on a global scale. To monitor the ionospheric scintillation ...
Center strategies for universal transformations: modified iteration policy and two alternative models
Although centralized coordinates are applied in geodetic coordinate transformations implicitly or explicitly, the centering strategy has not been comprehensively investigated from the theoretical perspective. In this contribution, we replace the ...
Continuous time and frequency transfer using robust GPS PPP integer ambiguity resolution method
GPS precise point positioning (PPP) technique has been widely used in time and frequency transfer. The performance of PPP can be improved if the phase ambiguities are fixed to the correct integer number. In this study, GPS PPP integer ambiguity ...
Feature-based GNSS positioning error consistency optimization for GNSS/INS integrated system
The estimated GNSS positioning error, which is commonly represented by measures such as variance or standard deviation, will determine the weight of measurements in the Kalman filter of GNSS/INS integration and significantly affect the integrated ...
Analysis of preliminary results from distributed autonomous timekeeping on Beidou-3 satellites
Autonomous timekeeping is necessary to maintain the navigation system time when the ground operation control system is unavailable. We use Ka-band inter-satellite two-way ranging data from Beidou-3 network satellites to carry out autonomous ...
A tropospheric delay model to integrate ERA5 and GNSS reference network for mountainous areas: application to precise point positioning
In this study, a tropospheric delay model that integrates tropospheric delays derived from the European Centre for Medium-Range Weather Forecasts fifth-generation global atmospheric reanalysis and the Continuously Operating Reference Station (CORS)...
An improved NeQuick-G global ionospheric TEC model with a machine learning approach
The advancements in computational resources and Artificial Intelligence (AI) technological tools can predict Global Ionospheric Maps (GIMs). The prediction of GIMs certainly helps the Global Navigation Satellite System (GNSS) users with ...