Research On Beidou Triple-Frequency Long-Baseline Ambiguity Fixed Algorithm And Its Application

BDS adopt multi-frequency technology in China. It can provide three frequency observation. Triple-frequency observation will form more longer wavelength, less noise and small ionospheric delay combination that is conducive to reduce the observation error. based on the existing dual theory, Cycle slip detection theory and ambiguity fixed algorithm in navigation and positioning technology using triple-frequency is deeply studied, which further improve the accuracy and efficiency of navigation and positioning. Therefore, the BDS triple-frequency cycle slip detection and ambiguity fixing for long baseline methods are researched and analyzed in detail, the main research contents are as follows:(1)Based on the analysis of dual-frequency navigation model, the triple-frequency combination theory is discussed, the combination of carrier phase observations are shown, then the selection criteria for the combinations is provided, and some common linear combination equations are derived.(2) Aim at the cycle slip detection problem of BDS three frequency observation data, The cycle slip detection methods of triple-frequency pseudo-range combination and triple-frequency geometry-free phase combination are deeply analyzed and validated using BDS triple-frequency observations. Results show that there has non-sensitive cycle slips existed in the two methods, so that the two methods cannot be independently applied in BDS triple-frequency cycle slip detection. Therefore, in the cycle slip detection it is necessary to combined a variety of methods according to the characteristics of the cycle.(3)In order to detect the cycle-slip in BDS triple-frequency observations during the ionosphere active period, a new method combined by geometry-free and ionosphere-free is put forward based on analyzing the characteristics BDS triple-frequency observations. On account of the disadvantages of this method, the second order epoch difference of geometry-free phase combination is also used to detect cycle-slips in BDS triple-frequency observations. And this method is validated by the triple-frequency data during ionosphere highly active period. The result indicates that this method can detect all the cycle slips under high ionospheric activity. So this method can be used in BDS triple-frequency cycle slip processing in real-time navigation and positioning.(4)The mixed integer model least squares ambiguity resolution process is derived; and the Geometry-free model of TCAR for short baseline ambiguity resolution is analyzed. Then the baselines of different length are used to verify the ambiguity resolution ability of the above Geometry-free model, results show that with the growth of the baseline length, taking into consideration the influences of ionosphere delay and troposphere delay, the ambiguity fluctuation range grows, cannot be directly fixed by rounding ambiguity.(5)For the problem ambiguity fixing difficulty of long baseline, the factors affecting long baseline ambiguity fixing are analyzed, and the ambiguity resolution theory using Geometry-based model of TCAR is researched, then a ambiguity fixing method through multi-epoch ambiguity smoothing is put forward. The wide-lane and extra-wide-lane combination after ambiguity fixing are used to form ionospheric-free combinations, which are used to obtain the BDS long baseline positioning results. It can be found that after ambiguity fixed of narrow-lane, the positioning accuracy is in centimeter level.(6)Using BDS triple-frequency relative positioning technology in landslide monitoring, Through the deformation monitoring platform to simulate landslide deformation process, with different length(30 m and 60 km and 110 km) of BDS baseline for the monitoring of the deformation process. The experimental results show that with the growth of the baseline length, its monitoring error is bigger and bigger. Finally, validating it through an example, analyzing and comparing with high precision total station monitoring results. The results show that single BDS triple-frequency relative positioning technology can be used in the landslide deformation monitoring completely.