Objective The uncertainty of influencing factors of BDS positioning is great in the disaster environment and emergency scene. The applicability and maneuverability of receiver in disaster emergency environment may not meet the needs of positioning. Therefore, the method of augmented positioning between long range stations on smart device was researched to meet the demand high-precision positioning in disaster emergency environment. The augmented positioning algorithm is convenient for high efficiency and easy to realize, and the user can use a very flexible data processing method.
Methods The un-difference error corrections between long-range reference stations was used of augmented positioning. The satellite clock error was eliminated and the atmospheric error and satellite orbit error can be weakened by the un-difference error corrections. The augmented positioning of user including pseudo-range, carrier phase and carrier phase smoothing pseudo-range between long range stations were achieved. And the demand of high-precision positioning of long range was meted by corrections of classified errors. The method of carrier phase smoothing pseudo-range by un-difference error corrections was used. The integer ambiguity was estimated by observations with eliminating errors and the pseudo-range was recalculated by the simple smoothing formula. The user station errors were removed or corrected by the reference station smoothing error corrections.The pseudo-range observations do not involve ambiguity with simple positioning mode and high- real-time performance, at the same time the accuracy of pseudo-range positioning can be improved by carrier phase observations. And this method can be better applied to the demand for high-precision positioning in disaster environment. The augmented positioning for specific receiver equipment was also integrated in the smart device.
Results Three reference stations between long range together with smart device and receiver in North China were used to test the augmented positioning. The positioning accuracy of dm or cm can be obtained by augmented positioning with pseudo-range and carrier phase smoothing of receiver, the accuracy on cm level obtained with carrier phase. The smart device can get the position on dm level of horizontal with carrier phase smoothing augmented positioning, and the augmented positioning with carrier phase was able to achieve the accuracy on cm level by fixed ambiguity or float ambiguity. The kinematic augmented positioning of smart device can get the positioning accuracy better than 1 meter with the test at Liaoning.
Conclusions The smart device can be used as the source of observation and the carrier of data processing for user receiver positioning. The results indicate that the method can achieve high-precision positioning with real-time dynamic centimetre, decimetre and sub-meter levels better than 1 meter.
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