A comparative study of equatorial radio source scintillations and the scintillations expected for ATS-6 emissions over India

Abstract

The aim of the paper is (1) to report equatorial radio source scintillations at 327 MHz observed by the giant radio telescope at Ooty, India; (2) to compare these results with the existing Fremouw-Rino global model (1971); and (3) to estimate the scintillation indices that may be expected from the Fremouw-Rino model for the years 1975-1976 for ATS-6 beacon transmissions. The Fremouw-Rino model grossly underestimates the scintillation indices by as much as one order of magnitude at low solar activity levels. This is probably due to the fact that the model was meant to give an overall picture of global morphology and that accuracy for any geographical region depends on the statistical significance of data input, which in this case is inadequate. Scintillation indices were computed for the Indian SITE program using the ATS-6 satellite. It is shown that at all stations, the predicted indices of scintillation are insignificant, but this may be misleading because of the inadequacy of the model for low latitudes.