Fading of radio signals from spaced synchronous satellites: dependence on source coordinates

Abstract

The fading of radio signals from synchronous satellites has been investigated, by analyzing the fading records radiated from a system of spaced synchronous satellites, all radiating at 136 MHz, and observed at Legon, Ghana: longitude 0.19° west, latitude 5.63° north and magnetic dip 8.47° south; for the occurrence of scintillation. In particular, the dependence of scintillation occurrence on source coordinates, especially the elevation, was investigated. The investigations revealed, amongst others, that: Equatorial scintillation is indeed a nocturnal phenomenon. Moreover, it sets in rather abruptly about sunset, and disappears sluggishly about dawn and shows a peak occurrence between 2100 h and 0300 h depending on observer's coordinates and the season. Scintillation occurrence, hence signal fading depends strongly on source elevation, and local time. The onset of scintillation is essentially, a west-east event; and it depends strongly on the elevation of the source, the lower the elevation the earlier the onset. Plausible explanations for the observations are proffered.

Keywords: equatorial ionospheric scintillation; radio signal fading; source coordinate; spaced synchronous satellites

Nigeria Journal of Pure and Applied Physics Vol. 4(1) 2005: 1-10