scholarly journals Determination of Ionospheric Delay Scale Factor for Low Earth Orbit using the International Reference Ionosphere Model

2014 ◽  
Vol 30 (2) ◽  
pp. 331-339 ◽  
Author(s):  
Jeongrae Kim ◽  
Mingyu Kim
Keyword(s):  
Scale Factor ◽  
Low Earth Orbit ◽  
Ionospheric Delay ◽  
International Reference Ionosphere ◽  
Earth Orbit ◽  
International Reference ◽  
Ionosphere Model

scholarly journals Comparative Preliminary Ionospheric Forecasting In Romania With Data From The European Ionosonde Service Versus Data Extracted From The International Reference Ionosphere Model

2015 ◽  
Vol 21 (3) ◽  
pp. 706-711
Author(s):  
Simona Miclaus ◽  
Paul Bechet ◽  
Mircea Stanic ◽  
Cora Iftode
Keyword(s):  
Time Of Day ◽  
International Reference Ionosphere ◽  
Quality Data ◽  
Radio Link ◽  
Ionospheric Layer ◽  
International Reference ◽  
Ionosphere Model ◽  
Data Links ◽  
Critical Frequency Fof2 ◽  
Model Versus

Abstract Radiocommunications in the HF band depend on the ionospheric parameters of radiowaves reflexion, though the quality of a radio link depends on: the time of day; season; solar cycle; geographical position. Taking into account the ionosphere characteristics over Romania, a forecasting is made over four cities in our country in order to provide the values of the critical frequency foF2 of the F2 ionospheric layer over a 24 hours cycle. A comparative analysis of this parameter is applied by using the International Reference Ionosphere model and interpolated experimental data collected from the European Ionosonde Service. Results show that the f0F2 values are slightly underestimated in all four locations in the model versus measurements, sustaining the necessity of own measurements in order to prepare quality data links in Romania if HF band is to be used for emergency data communications.

scholarly journals Orbit Propagation and Determination of Low Earth Orbit Satellites

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Ho-Nien Shou
Keyword(s):  
Kalman Filter ◽  
Real Time ◽  
Unscented Kalman Filter ◽  
Estimation Method ◽  
Nonlinear Problems ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Positioning Accuracy ◽  
Orbit Propagation

This paper represents orbit propagation and determination of low Earth orbit (LEO) satellites. Satellite global positioning system (GPS) configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP). The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan to use a nonlinear filtering method for immediate orbit tasks requires more precise satellite orbit state parameters in a short time. Although the traditional extended Kalman filter (EKF) method is widely used, its linear approximation of the drawbacks in dealing with nonlinear problems was especially evident, without compromising Kalman filter (unscented Kalman Filter, UKF). As a new nonlinear estimation method, it is measured at the estimated measurements on more and more applications. This paper will be the first study on UKF microsatellites in LEO orbit in real time, trying to explore the real-time precision orbit determination techniques. Through the preliminary simulation results, they show that, based on orbit mission requirements and conditions using UKF, they can satisfy the positioning accuracy and compute two indicators.

Real-time orbit determination of Low Earth orbit satellite based on RINEX/DORIS 3.0 phase data and spaceborne GPS data

2020 ◽  
Vol 66 (7) ◽  
pp. 1700-1712
Author(s):  
Chongchong Zhou ◽  
Shiming Zhong ◽  
Bibo Peng ◽  
Jikun Ou ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Low Earth Orbit ◽  
Gps Data ◽  
Earth Orbit ◽  
Orbit Satellite ◽  
Low Earth Orbit Satellite ◽  
Phase Data

scholarly journals Improvements to Predictions of the Ionospheric Annual Anomaly by the International Reference Ionosphere Model

2018 ◽  
Author(s):  
Steven Brown ◽  
Dieter Bilitza ◽  
Erdal Yiğit
Keyword(s):  
Northern Hemisphere ◽  
International Reference Ionosphere ◽  
Model Data ◽  
Iri Model ◽  
International Reference ◽  
Data Comparison ◽  
Ionosphere Model ◽  
Model Predictions ◽  
One Year ◽  
Underlying Processes

Abstract. The annual anomaly is the ionospheric phenomena in which the globally-averaged electron density is greater in January than it is in July. This anomaly causes the ionospheric solsticial variation – a variation with a periodicity of one year that is in-phase with the January solstice – to be more pronounced over the Northern Hemisphere than the Southern Hemisphere. Predictions of the magnitude of annual anomaly using the International Reference Ionosphere (IRI) model have been shown to be unreliable so far. The objective of our study is to investigate model prediction of the magnitude of the annual ionospheric anomaly using new ionospheric indices as inputs in the IRI model. These new indices improve predictions ionospheric variations that differ over the two hemispheres. We present a retrospective analysis of the IRI predictions of the ionospheric daytime annual anomaly and solsticial variation using a model-data comparison with observations from over 40 ionosondes for high, moderate, and low solar cycle conditions. Our results show that there is an overall 33 % underestimation of the magnitude of the annual anomaly when the by the IRI. When the new ionospheric indices as used in the IRI, model predictions underestimate the magnitude of the annual anomaly by 6 %. This indicates an improvement of the model predictions when using the new indices. We show that the underestimation of the annual anomaly by IRI is related to a similar underestimation of the magnitude of the ionospheric solsticial variation over the Northern Hemisphere. Based on our results, we infer that the underlying processes of the annual anomaly must vary across each hemisphere.

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