A Study of Time Dissemination via Satellite in India

B.S. Mathur, P. Banerjee, P.C. Sood, Mithlesh Saxena, Nand Kumar, A.K. Suri

Abstract:	The availability of French-German satellite Symphonie, coupled with the increasing demand on accuracy and coverage by the Indian users, provided an opportunity to carry out time transfer experiments with satellite, thus to enable us to have some gainful experience on the merits and demerits of different possible modes of time transfer via satellite. We report some of these observations and analysis in this paper. A simultaneous two-way clock synchronization experiment between three Earth stations, New Delhi (DES), Ahmedabad (AES) and Madras (MES) was performed and improvements over the technique earlier attempted in India, where transmit/receive roles of the two stations were alternated at regular intervals, were studied. The National Physical Laboratory, New Delhi (NPL) has been disseminating standard time and frequency signals, under the call sign "ATA," at three carrier frequencies, 5, 10 and 15 MHz. To study the improvements over the existing HF broadcast, a similar time format as used in HF "ATA" transmissions was disseminated via satellite Symphonie and was studied at DES, AES, MES and the mobile terminal TRACT located at Calcutta. The Time signals via these two modes (HF and satellite) were critically monitored at AES and analysed. This time format was later mod 1fied to include the additional information about time of the day in year, month, day, hour, minute and second as well as DUT1 in BCD code and was disseminated via the satellite from DES. These signals were decoded, displayed and studied at DES, AES, MES and with TRACT at Calcutta, thus covering a very large cross-section of India. Some preliminary work on time transfer via TV using direct satellite broadcast, is also reported.
Published in:	Proceedings of the 11th Annual Precise Time and Time Interval Systems and Applications Meeting November 27 - 29, 1979 Goddard Space Flight Center Greenbelt, Maryland
Pages:	387 - 402
Cite this article:	Mathur, B.S., Banerjee, P., Sood, P.C., Saxena, Mithlesh, Kumar, Nand, Suri, A.K., "A Study of Time Dissemination via Satellite in India," Proceedings of the 11th Annual Precise Time and Time Interval Systems and Applications Meeting, Greenbelt, Maryland, November 1979, pp. 387-402.
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