INTERSYSTEM INTERFERENCE DUE TO HYDROMETEOR SCATTERING ON SATELLITE DOWNLINK SIGNALS IN TROPICAL LOCATIONS

Abstract

This paper computes intersystem interference due to scattering by hydrometeors into the downlink receiver terminal of a communication satellite in three tropical locations, Ile-Ife (Nigeria), Nairobi (Kenya) and Douala (Cameroon). The evaluation procedure used was the simplified 3-D bistatic radar equation and the exponential rain-cell model. The results obtained in this study show that the cumulative distribution of effective transmission loss (Le) is much lower than the cumulative distribution of transmission loss in all the locations. For instance, at time percentage unavailability of 0.01%, the effective transmission loss is lower than the transmission loss by 20 dB in Douala, 15 dB at Ile-Ife and 11 dB in Nairobi. The lower the effective transmission loss, the higher is the interference in the satellite receiver. Also,a comparison of the effective transmission loss in the regions shows that Douala has the worst effective transmission loss, that is, highest interference at all frequencies and time percentages. Therefore, while it is acknowledged that satellite fade outs at frequencies greater than 10 GHz is a problem in these locations, it may be deduced that Douala has comparatively the highest frequency of outages.