Equatorial Radio Scintillations of ATS-6 Radio Beacons: Phase II-Ootacamund 1975-76

Abstract

Temporal variations of the amplitude fluctuations of the radio beacon signals on 40, 140 and 360 M Hz transmitted from the ATS-6 satellite (at 34°E longitude) received at Ootacamund (11.4 N, 76.7 E, magnetic dip 6° N) during the second phase ofthe ATS-6 programme (1975-76) are described. For 360 MHz beacon, the mean scintillations index had two minima of about1% (about 0.1 dB) during the sunrise and sunset periods; a flat maximum of about 4% (0.4 dB) around midday and another maximum of about 13% (1.2 dB) around 2100-2200 hrs LT. The mean scintillation index on 140 MHz was minimum (0.6 dB) around sunrise and sunset hours and maxima of about 2 dB were at midday and nighttime. The magnitude of scintillations of 40 MHz was about 3 dB around sunrise and sunset periods and about 5 dB during midday and midnight hours. The nighttime scintillations were strongest in October 1975 (thus during equinoxes) while daytime scintillations did not indicate any definite seasonal variation.