1、QUESTION ITU-R 218-4/3Ionospheric influences on space systems(1990-1992-1995-1997-2007-2009)The ITU Radiocommunication Assembly,consideringa) that, in the case of some high-performance space systems involving satellites, ionosphericeffects should be considered up to the highest frequencies in use;b)
2、 that various satellite systems, including mobile- and navigational-satellite services,are employing non-geostationary-satellite networks,decides that the following Questions should be studied1 How can trans-ionospheric propagation models be improved, especially to account forionospheric changes in
3、the short-term, and at high and low latitudes, in regard to: scintillation effects on phase, angle of arrival, amplitude and polarization; Doppler and dispersion effects; refraction affecting in particular the direction of arrival and also the phase and groupdelays; Faraday effect, particularly with
4、 regard to polarization discrimination; attenuation effects?2 What propagation prediction methods can be derived to assist in coordination and sharingamong concerned services?3 What propagation prediction method can be derived to assist in the determination ofperformance characteristics of satellite
5、 services employing non-geostationary-satellite networks?4 What are the methods to simulate realistic time-series for system simulation includingrapidly varying propagation effects?further decides1 that the available information should be prepared as new Recommendations, or as revisionsto existing Recommendations;2 that Recommendation ITU-R P.531 will be revised before 2010.NOTE 1 Priority will be given to studies relating to 1.3 that the above studies should be completed by 2012.Category: S2
