Some tests of methods of analysis of ionospheric drift records using an array of 89 aerials

Abstract

Results from an array of 89 aerials are used to test the validity of the usual methods of measuring ionospheric drifts, in which only three aerials are used. It is shown that the magnitude of the ‘true’ velocity determined by ‘full correlation analysis’ increases as the size of the aerial triangle increases, and tends to a limit which is the correct value. The ‘apparent’ velocity, which is equal to the velocity obtained by the ‘method of similar fades’, shows no variation with triangle size, but gives consistently high values. The ‘correlation ellipse’ shows a tendency to be aligned along the hypotenuse when small right-angled triangles are used. An explanation of these results is given in terms of instrumental effects in the recording and digitizing process. It is suggested that there is an optimum aerial separation for spaced receiver experiments, and that this is considerably larger than has usually been employed in the past. For E-region measurements, an equilateral triangle of side about 300 m is recommended.