A COMPARISON OF THE FASF AND LEAST-SQUARES SEARCH ALGORITHMS FOR ON-THE-FLY AMBIGUITY RESOLUTION

D. Chen and Gerard Lachapelle

Peer Reviewed

Abstract: This paper describes an effective approach for ambiguity resolution on the fly (OTF) -- the Fast Ambiguity Search Filter (FASF) -- and presents comparative numerical results for this method and the least-squares search approach. In the past, the search range of each ambiguity parameter was determined separately regardless of the assumed integers of the other ambiguities. In the new approach presented here, the search range is determined recursively for each ambiguity parameter. The effect of an assumed integer on other ambiguities is then fully taken into account when determining the uncertainty range of an ambiguity parameter. Another important characteristic is that all observations from the initial to the current epoch are taken into account through the use of a Kalman filter. An index of possible inability to fix the ambiguities is used. Therefore, a full search of all possible integer ambiguities is not required, and the computation is dramatically reduced. Computer memory is also saved since there is no need to retain all potential solutions. Test results show that both the computation time for ambiguity search and the observation period required for ambiguity resolution are significantly reduced.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 42, Number 2
Pages: 371 - 390
Cite this article: Chen, D., Lachapelle, Gerard, "A COMPARISON OF THE FASF AND LEAST-SQUARES SEARCH ALGORITHMS FOR ON-THE-FLY AMBIGUITY RESOLUTION", NAVIGATION, Journal of The Institute of Navigation, Vol. 42, No. 2, Summer 1995, pp. 371-390.
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