Obtaining a Faster and More Accurate First Position Fix in Poor Signal Environments

Heidi Kuusniemi, Timo Jokitalo, Stefan Soderholm and Swama Kakarlapudi

Abstract:	This paper presents a methodology for obtaining a faster initial navigation solution in compromised signal conditions with greater reliability by utilizing high rate measurements and special averaging processing to smooth range observables. The advantages of using high rate measurements and a smoothing process until a first position solution is obtained include decreased time-tofirst- fix and reduced position error. This paper presents different ideas how high rate observations can be made the most of in poor signal-environments. Channel-wise smoothing Kalman filters are implemented for observation correction with an assumption of constant Doppler during the initialization period. Results from utilizing this smoothing process in hot start tests in different environments show the improvements in TTFF and first fix accuracy.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1405 - 1412
Cite this article:	Kuusniemi, Heidi, Jokitalo, Timo, Soderholm, Stefan, Kakarlapudi, Swama, "Obtaining a Faster and More Accurate First Position Fix in Poor Signal Environments," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1405-1412.
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