Abstract
Precise single-point positioning using carrier-phase measurements can be provided by the synchronized pseudolite system. The primary task of carrier phase positioning is ambiguity resolution (AR) with rapidity and reliability. As the pseudolite system is usually operated in the dense multipath environment, cycle slips may lead the conventional least-squares ambiguity decorrelation adjustment (LAMBDA) method to incorrect AR. A new AR method based on the idea of the modified ambiguity function approach (MAFA), which is insensitive to the cycle slips, is studied in this paper. To improve the model strength of the MAFA and to eliminate the influence of constant multipath biases on the time-average model in static mode, the kinematic multi-epoch MAFA (kinematic ME-MAFA) algorithm is proposed. A heuristic method for predicting the ‘float position’ corresponding to every Voronoi cell of the next epoch, making use of Doppler-based velocity information, is implemented to improve the computational efficiency. If the success rate is very close to 1, it is possible to guarantee reliable centimeter-level accuracy positioning without further ambiguity validation. Therefore, a computing method of the success rate for the kinematic ME-MAFA is proposed. Both the numerical simulations and the kinematic experiment demonstrate the feasibility of the new AR algorithm according to its accuracy and reliability. The accuracy of the horizontal positioning solution is better than 1.7 centimeters in our pseudolite system.
Highlights
In recent decades, the landscape of global navigation satellite system (GNSS) technology has undergone far-reaching transformations to cater for both civilian and military needs, used throughout the national infrastructure for providing positioning, navigation, and timing services
In precise single-point positioning of the pseudolite system, the carrier phase observations may suffer from cycle slips due to the dense multipath or the low-elevation pseudolite
Carrier phase measurements and Doppler measurements are used for multi-epoch ambiguity determination
Summary
The landscape of global navigation satellite system (GNSS) technology has undergone far-reaching transformations to cater for both civilian and military needs, used throughout the national infrastructure for providing positioning, navigation, and timing services. Some bias will be propagated into the float solution, resulting in wrong integer solution estimated by the LAMBDA algorithm [18] Another category of OTF AR algorithms is the search techniques in the coordinate domain, including the ambiguity function method (AFM) and the modified ambiguity function approach (MAFA), using only the fractional value of the carrier phase measurement, which are insensitive to the cycle slips [19]. Doppler measurements is used to help single-epoch determination of carrier-phase integer ambiguities in the conventional LAMBDA method [29]; its single-epoch ‘float solution’ must be calculated by updating an accurate previous position regarded as the result of correct ambiguities. A computing method of the success rate for the kinematic ME-MAFA is proposed
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