一定点におけるオメガ測位精度の微視的変動

抄録

In the former paper, we evaluated macroscopically the accuracies of positions determined by two or three Omega position lines based on the data of A-C, A-D, A-E, A-H, C-D, C-E, C-H, D-E, D-H and E-H pairs which were measured at a fixed point (41°48'. 4N, 140°43'. 3E) from January 1, 1977 until December 31, 1977. The accuracies of Omega position lines however, fluctuate depending on the season and hour. In this paper, we attempted to evaluate in detail laying stress on specific pairs. The combinations were A-C, A-H; A-H, C-H and A-C, D-H pairs which were evaluated highly in the former paper. 1) Accuracies of determined positions when propagation corrections are carried out by the use of PPC tables. The standard deviations around predicted values (obtained by correcting the values shown in the PPC tables to the phase differences between the observation point and the two stations) are shown monthly in Figs.1 and 2 assuming that the measured values have normal distributions around each predicted value. Based on the σ of each pair and the intersecting angles of two or three position lines the radii of 95 per cent probability circles were calculated and shown in Figs.3 and 4. 2) Accuracies of determined positions when propagation corrections are carried out by the use of measured ones. Each day was divided into twenty-four hours and each month into two parts, thus a year was divided into 576 parts, and each condition was considered to be the same respectively. The differences between the mean values and the measured values for each part presented observation errors. Figs.5 and 6 show the standard deviations of each pair corresponding to each season and time. Based upon those data and the angles cut in two or three position lines the radii of 95 per cent probability circles were calculated and are shown in Figs.7 and 8.