Results 41 to 50 of about 3,314 (215)

The Future of Time: UTC and the Leap Second

, 2011
Before atomic timekeeping, clocks were set to the skies. But starting in 1972, radio signals began broadcasting atomic seconds and leap seconds have occasionally been added to that stream of atomic seconds to keep the signals synchronized with the actual
Allen, Steve, Finkleman, David, Seago, John, Seaman, Rob, Seidelmann, P. Kenneth   +4 more
core   +1 more source

A GIVE Prediction Method in SBAS Based on GAT‐TCN

Space Weather, Volume 23, Issue 11, November 2025.
Abstract A Grid Ionospheric Vertical Error (GIVE) prediction model based on GAT‐TCN is proposed in this paper. The model integrates the Graph Attention Network (GAT) with the Temporal Convolutional Network to enhance prediction accuracy while ensuring the integrity of the Satellite‐Based Augmentation System, thereby improving its availability.
Hao Zhang, Yingkui Gong, Fei Zhao, Yuanhang Liu, Cheng Yu, Ziyue Hu, Yubo Zhu, Guang Yang, Hong Yuan   +8 more
wiley   +1 more source

A Flexible Ephemeris Representation for GNSS and Alternative PNT Signal Sources Using B-Splines

Navigation, 2023
Most global navigation satellite systems (GNSSs) ephemeris representations require straightforward, albeit specialized algorithms to compute the transmitter position at a time of interest.
Mikaela Dobbin, Penina Axelrad
doaj   +1 more source

Method and apparatus for autonomous, in-receiver prediction of GNSS ephemerides [PDF]

, 2012
Methods and apparatus for autonomous in-receiver prediction of orbit and clock states of Global Navigation Satellite Systems (GNSS) are described. Only the GNSS broadcast message is used, without need for periodic externally-communicated information ...
Bar-Sever, Yoaz E., Bertiger, William I.
core   +1 more source

Ionospheric Disturbances During the 4 December 2015, Mt. Etna Eruption

Earth and Space Science, Volume 12, Issue 10, October 2025.
Abstract This study presents the detection and characterization of co‐volcanic ionospheric disturbances (CVIDs) associated with Mt. Etna's large‐scale lava fountain (Italy). Leveraging a dense and proximal GNSS network, we identify local Total Electron Content (TEC) perturbations extending up to ∼ ${\sim} $200 km south/southwest of the vent.
F. Ferrara, M. Ravanelli, A. Bonforte, V. Capparelli, V. Carbone, S. Scollo, L. Mereu, A. Cannata   +7 more
wiley   +1 more source

Impacts of Satellite Orbit and Clock on Real-Time GPS Point and Relative Positioning

Sensors, 2017
Satellite orbit and clock corrections are always treated as known quantities in GPS positioning models. Therefore, any error in the satellite orbit and clock products will probably cause significant consequences for GPS positioning, especially for real ...
Junbo Shi, Gaojing Wang, Xianquan Han, Jiming Guo   +3 more
doaj   +1 more source

Phoenix-XNS - A Miniature Real-Time Navigation System for LEO Satellites [PDF]

, 2006
The paper describes the development of a miniature GPS receiver with integrated real-time navigation system for orbit determination of satellites in low Earth orbit (LEO).
Gill, Eberhard, Montenbruck, Oliver
core  

Real‐Time Regional Ionosphere Modeling With RFR‐Net Over China

Space Weather, Volume 23, Issue 8, August 2025.
Abstract The mid‐to‐low‐latitude ionosphere, influenced by phenomena such as the Equatorial Ionization Anomaly, responds more sensitively to changes in solar activity, which negatively affect the transmission of various electromagnetic signals. Moreover, next‐generation technologies, particularly Precise Point Positioning‐Real‐Time Kinematic (PPP‐RTK),
Mengfei Sun, Tong Liu, Zonghua Ding, Jian Liu, Yanshi Huang, Kun Zhang, Shengliang Fang, Shizhong Li, Qinglei Kong, Bo Chen   +9 more
wiley   +1 more source

Izračun položaja GPS-satelita iz podatkov oddanih efemerid : GPS-Orbit Computation from Broadcast Ephemeris Data [PDF]

Geodetski Vestnik, 2004
The article describes the theoretical point of view of the GPS-broadcast ephemerides application. Beside the raw GPS observations, any kind of GPS ephemerides represents indispensable data in the GPS processing engine.
Bojan Stopar, Polona Pavlovčič Prešeren   +1 more
doaj  

The Benefit of Space Clocks for the Deep Space Network

Radio Science, Volume 60, Issue 8, August 2025.
Abstract Ground‐based atomic clocks have been the foundation of the Deep Space Network's (DSN's) ability to provide high‐precision tracking to deep space users for navigation and radio science since its inception in the mid‐1960s. This paper describes the development of space clocks that could aid the DSN and the solar system exploration enterprise ...
T. Ely, E. Burt, K. Cheung, R. Tjoelker
wiley   +1 more source