TROPOSPHERIC SCINTILLATION EFFECTS ON SATELLITE LINKS FROM X-BAND TO Q-BAND OVER NIGERIAN CLIMATIC ZONES USING KARASAWA AND ITU-R MODELS

摘要

The tropospheric scintillation of satellite communication signals has continued to draw the attention of radio engineers. The effect and prevalent paucity of Earth-space tropospheric scintillation data in Africa are remarkable. The parameters of NigComSat-1R and Eutelsat-36B satellites were used for this modeling from X- to Q-band during the West African monsoon (WAM). The low error rates of Karasawa and ITU-R models reported for the tropical climates made them appropriate for this study. In situ data from the Tropospheric Data Acquisition Network stations spanning three climatic regions in Nigeria, namely Tropical Monsoon, Geo. 6.5° N, 3.5° E; Tropical Savanna, Geo. 8.99° N, 7.38° E; and the Sahel, Geo. 9.35° N, 12.5° E. The scintillation variability is lowest in the tropical monsoon climate and highest in the Sahel climate using both models. However, the ITU-R model recorded higher scintillation fade depths (SFDs) of 37.19 dB, 2.91 dB, and 2.52 dB, for low elevation, NigComSat-1R and Eutelsat-36B satellites respectively, over the tropical monsoon climatic zone, than Karasawa model, which recorded SFDs of 34.07 dB, 1.31 dB, and 1.09 dB for the respective satellites. The observed scintillation intensity increased with increasing carrier frequency, low elevation angle and small receiving antenna. High variability of the scintillation intensity characterizes the onset of WAM and post-monsoon months.