On Board Pointing Error Detection and Estimation of Observation Satellite Data using Extended Kalman Filter

The satellite communication is embellished constantly by providing information, ensuring security, and enables the communication among huge at a particular time efficiently. The satellite navigation helps in determining the people's location. The global development, natural disasters, change in climatic conditions, agriculture crop growth, etc. are monitored using satellite observation. Hence, the satellite includes detailed information data, it has to be protected confidentially. The field of the satellite is enhanced at an astonishing pace. Satellite data plays an important role in this modern world and hence, the onboard satellite data have to secure through the proper selection of error detection and estimation schema. The Extended Kalman Filter is widely used in the satellite system. EKF is utilized in this proposed model to detect the onboard pointing error such as attitude and orbit determination. An autonomous estimation of orbit position is possible through space-borne gravity. The information obtained through the observation of satellite data is compared with the accurate gravity model in detecting the error. The utilization of EKF reduces the dependence of the ground tracking system in satellite determination. The orbital altitude and orbital position are the most important challenges faced in the satellite determination system. The satellite model using the Extended Kalman Filter is a more apt method in estimating the orbital parameters. The errors in the linearization process are detected and this can be overcome through the proper selection of linear expansion point with EKF algorithmic model with the Jacobian matrix calculation. The results show that the EKF implementation helps in attaining better accuracy in comparison with other methodologies.

Prediction improvement of potential PV production pattern, imagery satellite-based

The results obtained by using an existing model to estimate global solar radiation (GHI) in three different locations in Tunisia. These data are compared with GHI meteorological measurements and PV_Gis satellite imagery estimation. Some statistical indicators (R, R2, MPE, AMPE, MBE, AMBE and RMSE) have been used to measure the performance of the used model. Correlation coefficient for the different stations was close to 1.0. The meteorology and satellite determination coefficient (R2) were also near 1.0 except in the case of Nabeul station in which the meteorology measurements (R) were equals to 0.5848 because of the loss of data in this location due to meteorological conditions. This numerical model provides the best performance according to statistical results in different locations; therefore, this model can be used to estimate global solar radiation in Tunisia. The R square values are used as a statistical indicator to demonstrate that the model’s results are compatible with those of meteorology with a percentage of error less than 10%.

A contemporary perspective of geoid structure

A contemporary perspective of geoid structureThe present paper reviews the contemporary state of definition and theory of the geoid. Key features are:quasigeoid, external gravitational field from satellites and its analytical downward continuation to the Earth's interior, data combination by least-squares collocation, and a new view of gravity reduction. This is done under the modern systematic perspective provided by the possibility of a purely geometric satellite determination of the Earth' surface by GPS combined with satellite altimetry.