Abstract
In this paper a new mathematical algorithm is proposed to improve the accuracy of DGPS (Differential GPS) positioning using several GNSS (Global Navigation Satellites System) reference stations. The new mathematical algorithm is based on a weighting scheme for the following three criteria: weighting in function of baseline (vector) length, weighting in function of vector length error and weighting in function of the number of tracked GPS (Global Positioning System) satellites for a single baseline. The algorithm of the test method takes into account the linear combination of the weighting coefficients and relates the position errors determined for single baselines. The calculation uses a weighting scheme for three independent baselines denoted as (1A,2A,3A). The proposed research method makes it possible to determine the resultant position errors for ellipsoidal BLh coordinates of the aircraft and significantly improves the accuracy of DGPS positioning. The analysis and evaluation of the new research methodology was checked for data from two flight experiments carried out in Mielec and Dęblin. Based on the calculations performed, it was found that in the flight experiment in Mielec, due to the application of the new research methodology, DGPS positioning accuracy improved from 55 to 94% for all the BLh components. In turn, in the flight experiment in Dęblin, the accuracy of DGPS positioning improved by 63–91%. The study shows that the highest DGPS positioning accuracy is seen when using weighting criterion II, the inverse of the square of the vector length error.
Highlights
The GNSS (Global Navigation Satellites System), as a satellite technology, is continuously developed and widely used in many areas of human life, including the entire aviation industry [1]
The proposed weighted average model presented in Equations (6)–(11) gives the possibility to determine the resultant positioning accuracy of the aircraft for the DGPS technique
The coorwas performed with a Cessna 172 aircraft and the duration of the experiment was from dinates of the GNSS reference stations were as follows: 09:48:00 a.m. to 11:05:44 a.m. according to GPST time
Summary
The GNSS (Global Navigation Satellites System), as a satellite technology, is continuously developed and widely used in many areas of human life, including the entire aviation industry [1]. It is important to note that the benefits of the GNSS in aviation are enormous, ranging from improved flight safety to reduced fuel emissions for example for RNAV (Area Navigation) [2] or the economic factor itself through improved airport capacity and an increased number of flight operations [3]. The calculation of the aircraft position in DGPS technique usually uses code observations at the L1 frequency of the GPS system, to ensure that it is possible to compare the pseudoranges between the GNSS reference station and the on-board GPS receiver [8] This comparison of pseudoranges for the same instant of time has been called differential satellite observations. The differential process itself allows for the reduction in many systematic errors such as satellite clock error, hardware TGD
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