241-244The amplitude and phase of 140 MHz transmissions from geostationary satellite ATS-6 (0oN, 35°E) have been recorded at Gauhati (26·15°N; 91·75°E) for the period Nov. 1975 to Aug. 1976. The calibration technique for geostationary satellite Faraday rotation measurements suggested by Checcacci and Giorgeo [Checcacci, P. F. & Giorgeo, M, T., J. almos.terr. Phys. 37 (1976),119] has been improved and generalized, It is then utilized to remove the nπ ambiguity in Faraday rotation values and also to estimate the correct value of diurnal minimum Faraday rotation angle so that the recorded Faraday rotation values can be converted into electron content values. Typical diurnal variation curves have been obtained for all the months except for equinoxes when the satellite transmission was off very often due to ecliptic conditions and hence no complete diurnal curves could be obtained for these months, It has been found that though December and January behave like typical winter months, the month of November is more like an equinoctial month. Similarly, though June and July behave like typical summer months the month of May is more or less similar to equinoxes. The characteristic features of the diurnal and seasonal behaviour of the electron content have been discussed
