Upgrades to the Inmarsat PN Transmission Test Bed and Initial Results

George Kinal and Oleg Razumovsky

Abstract:	The first results from Inmarsat’s PN transmission test program were reported at ION GPS-89, and served to indicate the feasibility of using geostationary satellite repeaters at L-band to transmit a GPS-like signal. The PN test bed has been undergoing improvement in several stages to enhance the stability of the signal and the accuracy of the measurement techniques. In the first upgrade, the time stability of the transmitted signal was greatly improved, so that residual short term jitter was comparable to GPS CA code. In the second stage, the transmitted PN clock is being compensated for satellite motion, so that the “virtual clock” will appear to be on the satellite. In the third stage, under development, the signal will also be modulated with data in the GPS format. This paper describes these upgrades, and reports on measurements taken at various stages of improvement. It also indicates how relatively inexpensive equipment can form the basis for timing compensation and satellite ranging systems needed to make a signal relayed through a “bent pipe” repeater function as an augmentation to the GPS system for civil applications.
Published in:	Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990) September 19 - 21, 1990 The Broadmoor Hotel Colorado Spring, CO
Pages:	315 - 322
Cite this article:	Kinal, George, Razumovsky, Oleg, "Upgrades to the Inmarsat PN Transmission Test Bed and Initial Results," Proceedings of the 3rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1990), Colorado Spring, CO, September 1990, pp. 315-322.
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