Summary

Abstract

From October 1964 to May 1969 the 40 MHz, 41 MHz, and 360 MHz signals of the satellite Explorer 22, were recorded at Lindau (51, 650°N; 10, 125°E). The Faraday effect recordings at 40 MHz and 41 MHz and Dispersive-Doppler-effect recordings at 40 MHz and 360 MHz were used to calculate the ionospheric electron content up to 1000 km. The mean electron content for 1 hour periods over a period of three months as obtained at 51. 6° N geographic latitude as derived from various evaluation methods is presented. Furthermore, the relevant critical frequency FOF2 is displayed. A similar presentation was chosen for the calculated slabthickness data. For one specific case the daily variation of the electron content as determined by measurements was compared with a relevant theoretical curve. The agreement, was fairly good. Due to technical problems the beacons were switched off in 1969. Now the five orbiting US-NNSS satellites provide a good possibility to determine the ionospheric electron content up to 1100 km fairly accurately by evaluating the Dispersive Doppler recordings obtained at 150 MHz and 400 MHz.