A New Approach for GNSS Frequency Selection Considering Detection of Cycle Slip Insensitive Pairs of Ionospheric Combination for Dual-Frequency Receivers

Junesol Song and Changdon Kee

Peer Reviewed

Abstract:	Carrier phase based positioning provides high level of positioning accuracy due to small noise error of its measurement. However, cycle slip can degrade positioning accuracy because it changes the integer ambiguity. Therefore, cycle slips should be detected and eliminated to guarantee precise positioning result. The linear combinations of the L1 and L2 carrier phase measurements are widely used to detect cycle slips since the distance term can be completely eliminated in those combinations. When the L1 and L2 carrier phases are linearly combined with some coefficients, the L1 and L2 integer ambiguities also form a linear combination with the same coefficients in the resultant measurement. Consequently, cycle slips in the combined measurement can be close to zero even for the presence of cycle slips on either carrier. In order to overcome this limitation, two different types of linear combinations are used simultaneously. The ionospheric combination and Hatch-Melbourne-Wubbena (HMW) combination are widely used for cycle slip detection since these combinations are complementary to each other. That is, the insensitive cycle slip pair of one combination can be detected by the other. On the other hand, the HMW combination has large noise errors since it is generated from pseudorange measurement. Even though the wavelength of the HMW combination is long, it may fail in detecting some insensitive cycle slip pair when the multipath errors in pseudorange measurement is significant. In this paper, we propose a new approach to validate detection of insensitive cycle slips of the ionospheric combination using additional linear combinations. By comparing the size of the cycle slip error and the standard deviation with appropriate confidence level for all possible linear combinations, we established that there exists no possible linear combination of the L1 and L2 frequencies which can detect the insensitive sets. Since the insensitive cycle slip pairs of linear combinations are intrinsic to the L1 and L2 frequencies, this approach is further applied to search theoretical L1 companion frequency that can detect or eliminate cycle slip insensitive pairs. As a result, the possible L1 companion frequencies in L-band are determined when the noise of the L1 carrier phase is approximately 0.3 mm. We also generated simulation measurement of the L1 and its companion frequency to verify the proposed approach. The proposed approach can be one of considerations to determine transmission frequencies of the additional signals for the current satellite navigation systems, as well as of the new satellite navigation systems in the future.
Published in:	Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015) September 14 - 18, 2015 Tampa Convention Center Tampa, Florida
Pages:	2681 - 2687
Cite this article:	Song, Junesol, Kee, Changdon, "A New Approach for GNSS Frequency Selection Considering Detection of Cycle Slip Insensitive Pairs of Ionospheric Combination for Dual-Frequency Receivers," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 2681-2687.
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