Results 31 to 40 of about 788,278 (206)

TerraSAR-X precise orbit determination with real-time GPS ephemerides [PDF]

Advances in Space Research, 2012
Abstract For active and future Earth observation missions, the availability of near real-time precise orbit information is becoming more and more important. The latency and quality of precise orbit determination results is mainly driven by the availability of precise GPS ephemerides and clocks. In order to have high-quality GPS ephemerides and clocks
Wermuth, Martin, Hauschild, André, Montenbruck, Oliver, Kahle, Ralph   +3 more
openaire   +2 more sources

Multi-GNSS Combined Orbit and Clock Solutions at iGMAS

Sensors, 2022
Global navigation services from the quad-constellation of GPS, GLONASS, BDS, and Galileo are now available. The international GNSS monitoring and assessment system (iGMAS) aims to evaluate the navigation performance of the current quad systems under a ...
Wei Zhou, Hongliang Cai, Guo Chen, Wenhai Jiao, Qianqian He, Yuguo Yang   +5 more
doaj   +1 more source

Extended Geometry and Probability Model for GNSS+ Constellation Performance Evaluation

Remote Sensing, 2020
We proposed an extended geometry and probability model (EGAPM) to analyze the performance of various kinds of (Global Navigation Satellite System) GNSS+ constellation design scenarios in terms of satellite visibility and dilution of precision (DOP) et al.
Lingdong Meng, Jiexian Wang, Junping Chen, Bin Wang, Yize Zhang   +4 more
doaj   +1 more source

Precision Ephemerides for Gravitational-wave Searches – IV. Corrected and refined ephemeris for Scorpius X-1

Monthly Notices of the Royal Astronomical Society, 2023
ABSTRACTLow-mass X-ray binaries have long been theorized as potential sources of continuous gravitational-wave radiation, yet there is no observational evidence from recent LIGO/Virgo observing runs. Even for the theoretically ‘loudest’ source, Sco X-1, the upper limit on gravitational-wave strain has been pushed ever lower.
T L Killestein, M Mould, D Steeghs, J Casares, D K Galloway, J T Whelan   +5 more
openaire   +2 more sources

Low‐Complexity Hybrid Beamforming for LEO Satellites: Beam Update Rate Analysis and Advanced Adaptive Precoding

International Journal of Satellite Communications and Networking, EarlyView.
ABSTRACT Low Earth Orbit (LEO) satellite constellations offer unprecedented opportunities for global broadband connectivity but pose significant beamforming challenges due to rapid platform motion and stringent onboard hardware constraints. Fully digital architectures, while optimal in theory, remain impractical for satellite payloads, motivating ...
Mohammad Momani, Thomas Delamotte, Andreas Knopp   +2 more
wiley   +1 more source

The natural satellites ephemerides facility MULTI-SAT

, 2008
Context. There is a need in some research facilities for deriving ephemerides, controlling observations, verifying various models of motion, and calculating the coordinates in space of natural planetary satellites. Aims. The goal of our work is
Emelyanov, Nikolai V., N. V. Emel'yanov, Arlot, Jean-Eudes, J.-E. Arlot   +3 more
core   +1 more source

A Short-Term Forecasting Method of Inter-Frequency Clock Bias for GPS Block IIF Satellites

Remote Sensing, 2022
The time-varying biases within carrier phase observations are integrated into satellite clock offset parameters for precise clock estimation. Consequently, when the precise satellite clock bias is applied to the third frequency observation for precise ...
Caiya Yue, Yamin Dang, Shuqiang Xue, Hu Wang, Shouzhou Gu, Changhui Xu   +5 more
doaj   +1 more source

SMTC Configuration and Window Adjustment Strategies for Beam Hopping in NR‐NTN

International Journal of Satellite Communications and Networking, EarlyView.
ABSTRACT Beam hopping is an effective transmission strategy for nonterrestrial networks (NTNs), enabling satellites to allocate limited power and spectrum resources across different geographical regions over time. However, in NR‐based NTN systems, beam hopping complicates synchronization monitoring because synchronization signal block (SSB) arrivals ...
Hee Wook Kim, Kyungrak Lee, Joon Gyu Ryu
wiley   +1 more source

A High-precision, Differentiable Code for Solar System Ephemerides

The Planetary Science Journal
Abstract We present jorbit , a python/ JAX library designed to enable modern data-driven numerical studies of the solar system. Written entirely in JAX , an autodifferentiable and optionally GPU ...
Ben Cassese, Malena Rice, Tiger Lu
openaire   +2 more sources

Precision Ephemerides for Gravitational-wave Searches – III. Revised system parameters of Sco X-1 [PDF]

Monthly Notices of the Royal Astronomical Society, 2018
11 pages, 7 figures.
Wang, L., Steeghs, D., Galloway, D. K., Marsh, T., Casares, J.   +4 more
openaire   +2 more sources