Satellite signals

Abstract

The scintillation of satellite-emitted radio signals has been observed using two different techniques, namely, doppler-shift frequency measurements and radio direction finding. Variations from a smooth doppler-shift curve obtained during individual orbits give a measure of frequency scintillation and thus of the roughness of the ionospheric path between the satellite and the observer. As expected, these variations are a function of frequency. Examples of the range of scintillations are given; both as a function of frequency and as correlated with an artificial ionospheric disturbance (Argus). Variations in direction-finder bearings are presented and their rate of change is discussed in relation to the roughness of the ionosphere. Both techniques are applicable to measurement of the hyperfine structure of the ionosphere. Tentative indices of ionospheric inhomogeneities are presented; namely, scintillation quality index from doppler measurements and probability of angular deviation from direction-finding technique.