DGPS Method 4 and Its Error Characterization

Chun Yang

Abstract:	Differential GPS (DGPS) technique has been shown viable in generating accurate position, velocity, and time measurements for a wide range of applications. According to which set of differential corrections is used: (1) in the solution domain with position error correction, (2) in the measurement domain with pseudorange error correction, or (3) in the error source domain with ephemeris error and clock bias correction and where the correction is applied: either on board the user platform or in the user’s ground control/processing station, there are six DGPS methods. In the case of ground processing, if counting the way in which GPS data are transferred, the use of IF signal with analog or digital translators could be the seventh method. In this paper, DGPS Method 4, i.e., downlink of uncorrected position data for ground differential processing, is considered. This method is particularly suitable for such applications as test range target control or post-flight processing where no corrected data are needed on board the user’s platform and the final position data must be made available on the ground. Such a DGPS method has other advantages in terms of cost, power consumption, size, and overall system complexity. After analyzing Method 4 errors in terms of orbital error projection, spatial decorrelation, and line of sight deflection, a new implementation scheme is set forth. In the new scheme, user position fixes transmitted or recorded as in conventional Method 4 are viewed as “pseudorange compression,” from which errors due to orbital error projection and line of sight deflection can be eliminated.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	889 - 897
Cite this article:	Yang, Chun, "DGPS Method 4 and Its Error Characterization," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 889-897.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In