Three Carrier Ambiguity Resolution: Generalised Problems, Models, Methods and Performance Analysis Using Semi-Generated Triple Frequency GPS Data

摘要

In this paper, the problems of three carrier phase ambiguity resolution (TCAR) and position estimation (PE) are generalised as real time GNSS data processing problems for a continuously observing network of any large scales. In order to describe these problems, a general linear equation system is presented that combines uniforms various geometry-free, geometry-based and geometry-constrained TCAR models, along with state transition questions between observation times. With this general formation, generalised TCAR solutions are given to cover all the real time GNSS data processing scenarios, which can also be simplified to various integer solutions, such as geometryfree rounding and geometry-based LAMBDA solutions with single and multiple epoch measurements. In fact, various ambiguity resolution (AR) solutions differ in the floating ambiguity estimation and integer ambiguity search processes, although their theoretical equivalence depends on use of the exactly same observational systems models and assumptions. A few key performance benefits achievable with semi-generated triple frequency GPS data from several dual-frequency GPS data sets from the baselines with respective 53km, 78km and 155km in length are demonstrated. These benefits include: (1) with the geometry-based and geometry-free TCAR models, the AR success rates of the two best Extra-widelane (EWL) observables from single-epoch L1, L2 and L5 signals reach almost 100%; (2) using these two ambiguity-fixed EWL signals or other derived WL signals, the ionosphere biases can be determined to the level of centimetres; (3) the ambiguity of the third observable can be fixed to 100% success within the measurements of several minutes; and (4) position estimation using an ambiguity-fixed and ionosphere-free WL observable achieves a 3D RMS accuracy of better than 20 centimetres, where the residual tropospheric errors dominate. With respect to the current dual-frequency based wide area GPS solutions, such as Precise Point Positioning (PPP) solutions, a major benefit of using the additional signals is the reduction of filtering time for the decimetre RMS accuracy from a few tens of minutes to a few minutes.