caa a22 4500 606162380 CHVBK 20210128100638.0 cr unu---uuuuu 210128e20151001xx s 000 0 eng 10.1007/s10291-014-0421-5 doi (NATIONALLICENCE)springer-10.1007/s10291-014-0421-5 Three-carrier ambiguity resolution using the modified TCAR method [Elektronische Daten] [Qile Zhao, Zhiqiang Dai, Zhigang Hu, Binzi Sun, Chuang Shi, Jingnan Liu] Multi-frequency technique is expected to be widely adopted with the new generations of global navigation satellite system, which is anticipated to benefit ambiguity resolution (AR). Three-carrier AR (TCAR) is a classical AR method based on triple-frequency observations, which is efficient for AR of short baseline. However, this method ignores the residual ionospheric delay, which degrades the reliability in active ionosphere situations and reduces the success of AR for medium and long baselines. We investigate the classical TCAR method and identify the major deficiency that hampers its application, especially to medium and long baselines. To improve this algorithm, the second and third steps of the classical TCAR are modified accordingly. In step 2, the ambiguity-resolved extra-wide-lane (EWL) combination and three pseudorange observations are employed to eliminate or reduce the residual ionospheric delay, in addition to the geometry term. In step 3, besides the EWL combination and pseudoranges, the ambiguity-resolved wide-lane (WL) combination is used to completely eliminate the ionosphere and geometry terms. The combination coefficients of these pseudoranges and combinations are optimized to minimize the noise of the ambiguity estimates. In order to assess the performances, real triple-frequency observations of BeiDou navigation system of baselines with different lengths are processed by the two methods. Results show that, the classical TCAR method is very sensitive to ionospheric delay and limited to short baseline application, while the modified TCAR method is free from ionospheric delay and can be applied to AR of median and long baselines. For WL AR, the modified TCAR method shows a comparable performance with the classical TCAR method, and a better performance can be expected when the baseline becomes longer, e.g., from 100s to 1,000s kilometers. For narrow-lane AR, the modified TCAR method performs much better than the classical TCAR method for median and long baselines. Springer-Verlag Berlin Heidelberg, 2014 TCAR nationallicence CIR nationallicence Ambiguity resolution nationallicence GNSS nationallicence GPS nationallicence BDS nationallicence Galileo nationallicence Zhao Qile GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut Dai Zhiqiang GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut Hu Zhigang GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut Sun Binzi GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut Shi Chuang GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut Liu Jingnan GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut GPS Solutions Springer Berlin Heidelberg 19/4(2015-10-01), 589-599 1080-5370 19:4<589 2015 19 10291 https://doi.org/10.1007/s10291-014-0421-5 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10291-014-0421-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhao Qile GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut NATIONALLICENCE 700 1- Dai Zhiqiang GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut NATIONALLICENCE 700 1- Hu Zhigang GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut NATIONALLICENCE 700 1- Sun Binzi GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut NATIONALLICENCE 700 1- Shi Chuang GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut NATIONALLICENCE 700 1- Liu Jingnan GNSS Research Center, Wuhan University, 129 Luoyu Road, 430079, Wuhan, China aut NATIONALLICENCE 773 0- GPS Solutions Springer Berlin Heidelberg 19/4(2015-10-01), 589-599 1080-5370 19:4<589 2015 19 10291