Y. V. Somayajulu

A multi-station satellite radio beacon study of ionospheric variations during total solar eclipses

Faraday rotation data obtained at Delhi, Kurukshetra, Hyderabad, Bangalore, Waltair, Nagpur and Calcutta during the total solar eclipse of 16 February 1980 and at Delhi during the total solar eclipse of 31 July 1981 have been analysed to detect the gravity waves generated by a total solar eclipse as hypothesized by Chimonas and Hines (1970, J. geophys. Res. 75, 875). It has been found that gravity waves can be generated by a total solar eclipse but their detection at ionospheric heights is critically dependent on the location of the observing station in relation to the eclipse path geometry. The distance of the observing station from the eclipse path should be more than 500 km in order to detect such gravity waves.

Satellite radio beacon monitoring of the troposphere

Abstract In this communication some effects of characteristic enhancements and/or fluctuations of the satellite radio beacon transmissions are described. It is convincingly shown that these effects are of tropospheric origin. The satellite radio beacon can thus be used for monitoring the tropospheric events.

Clock Synchronization Experiment in India Using Symphonie Satellite

A recent clock synchronization experiment between the National Physical Laboratory (NPL), New Delhi and Space Applications Centre (SAC), Ahmedabad via geostationary satellite symphonie-II, stationed at 49°E longitude, is reported in this paper. As only one satellite transponder was available for this experiment, the two-way transmission of the clock pulses was carried out by switching the transmit—receive roles at the two stations at 5 minute intervals to achieve a nearly simultaneous two-way transmission. Taking into account all the additional delays, the results demonstrated a clock—synchronisation accuracy of better than 0.5 μs. A crystal-based portable clock flown aboard an aircraft confirmed this clock-synchronization to within a microsecond.