Abstract
Due to the great influence of multipath effect, noise, clock and error on pseudorange, the carrier phase double difference equation is widely used in high-precision indoor pseudolite positioning. The initial position is determined mostly by the known point initialization (KPI) method, and then the ambiguities can be fixed with the LAMBDA method. In this paper, a new method without using the KPI to achieve high-precision indoor pseudolite positioning is proposed. The initial coordinates can be quickly obtained to meet the accuracy requirement of the indoor LAMBDA method. The detailed processes of the method follows: Aiming at the low-cost single-frequency pseudolite system, the static differential pseudolite system (DPL) method is used to obtain the low-accuracy positioning coordinates of the rover station quickly. Then, the ambiguity function method (AFM) is used to search for the coordinates in the corresponding epoch. The real coordinates obtained by AFM can meet the initial accuracy requirement of the LAMBDA method, so that the double difference carrier phase ambiguities can be correctly fixed. Following the above steps, high-precision indoor pseudolite positioning can be realized. Several experiments, including static and dynamic tests, are conducted to verify the feasibility of the new method. According to the results of the experiments, the initial coordinates with the accuracy of decimeter level through the DPL can be obtained. For the AFM part, both a one-meter search scope and two-centimeter or four-centimeter search steps are used to ensure the precision at the centimeter level and high search efficiency. After dealing with the problem of multiple peaks caused by the ambiguity cosine function, the coordinate information of the maximum ambiguity function value (AFV) is taken as the initial value of the LAMBDA, and the ambiguities can be fixed quickly. The new method provides accuracies at the centimeter level for dynamic experiments and at the millimeter level for static ones.
Highlights
The outdoor global navigation satellite system (GNSS) has been developed and widely applied, but it is difficult to obtain reliable GNSS signals in sheltered environments or indoors
Due to the complexity of the indoor environment, this paper mainly focuses on the static double difference (DD) pseudorange/carrier phase observations of the zero this paper mainly focuses on the static DD pseudorange/carrier phase observations of the zero baseline baseline and short baseline
GNSSdifferential differentialpseudorange pseudorangepositioning, positioning,the theinitial initialvalue valueof ofthe therover roverstation station can be given by because the constellations of satellites are changing at all times and can be given by SPP because the constellations of satellites are changing at all times andthe thenumber number of a more accurate value cancan be be obtained in ainfew epochs
Summary
The outdoor global navigation satellite system (GNSS) has been developed and widely applied, but it is difficult to obtain reliable GNSS signals in sheltered environments or indoors. A pseudolite system can make up for the shortage of GNSS in these environments [1,2]. There are many problems in the indoor pseudolite systems, such as clock synchronization, multipath effect, noise, fixed satellite constellations, the high precision requirement of initial values, and so on. All of them are significant challenges for indoor pseudolite positioning. The most mature indoor pseudolite system is produced by LOCATA.
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