Accuracies of Position Fixes Obtained by NNSS at a Fixed Station-IV : The Tendency and Comparison of Position Accuracies by each Satellite

Abstract

Improvement of the technology applied in satellite has been made both in hardware and software, and there are changes in installation in NNSS; especially the injection of NOVA satellite. Thereby it is necessary to revalue the accuracy of fixes by the system. In this paper we made discussion on the diurnal and seasonal variation of accuracy of fixes by NNSS, and found the variation in the element of satellite orbit. Finally, we found the relation between the accuracy of fixes and the transverse from the plane of satellite's orbit. The results of analysis are as follows: (1) The diurnal variation of accuracy of fixes by single channel (400MHz only) shows a similar tendency to the diurnal variation of the electron density of ionosphere, but the seasonal one of that is consistent with the amplitude of the variation of the critical frequency. The accuracy of fixes by dual channel (400MHz/150MHz) is effected mainly by the condition of the atmosphere. (2) The variation of the elements of NOVA's orbit is merely 1/3 comparing with the correspondent one of satellite (No.11). Though there is no correlation between the error of the transverse and the one of latitude, the error of the transverse causes a error portion 1 to that one in longitude.