STANDARD TIME AND FREQUENCY SIGNAL DISSEMINATION INSAT-1B SERVICE VIA INDIAN DOMESTIC SATELLITE

A. Sen Gupta, A.K. Hanjura, P. Banerjee, B.S. Mathur

Abstract:	INSAT-1B is a multipurpose Indian Domestic Satellite parked on the equator at 74°E. It has twelve transponders in C-Band and two in C/S Band. One of the narrowband injected carriers in one C/S band transponder is dedicated for Standard Time and Frequency Signal (STFS) dissemination. The uplink frequency of this channel is 5899.675 MHz and downlink is 2599.675 MHz. The permissible RF bandwidth is 160 KHz and audio bandwidth 10 KHz. The STFS used, consists of a train of 5 KHz bursts which is frequency modulated on the carrier. The coded information on the IST clock and satellite position is transmitted by binary modulation of the width of 5 KHz packets. The satellite position coordinates are updated every 10 minutes to take care of the propagation delay corrections. The STFS format generator driven by Cesium frequency standard is interfaced with the INSAT earth station uplink channel. The receiving setup consists of an 8-foot chicken mesh antenna, front-end converter, FM demodulator, and a microprocessor controlled signal decoder. The decoder not only extracts the coded information of IST and the satellite position coordinates but also makes measurements of the time interval between the received signal and a local 1 pps. Preliminary investigations on the performance of this dissemination scheme were carried out by receiving the signal at the Earth Station site. These measurements indicate the time transfer capability with a precision of better than 1 microsecond and accuracy of better than 20 microseconds. The inaccuracy comes mainly because of the uncertainty in the satellite position prediction.
Published in:	Proceedings of the 19th Annual Precise Time and Time Interval Systems and Applications Meeting December 1 - 3, 1989 Sheraton Hotel Redondo Beach, California
Pages:	381 - 398
Cite this article:	Gupta, A. Sen, Hanjura, A.K., Banerjee, P., Mathur, B.S., "STANDARD TIME AND FREQUENCY SIGNAL DISSEMINATION INSAT-1B SERVICE VIA INDIAN DOMESTIC SATELLITE," Proceedings of the 19th Annual Precise Time and Time Interval Systems and Applications Meeting, Redondo Beach, California, December 1987, pp. 381-398.
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