Abstract
The Loran C, [SS3], data of 1967-1971 were analysed as follows ; In the propagation route of Y rate over seawater, the constant deviations versus the distance from the master station were shown for linearly correlation, and the constant is ±3.2μs/100n.m. The deviation of X rate observed at Hiraiso was agreed with this constant in spite of the different area. The seasonal variation of the reflecting height was found at night and these stability was superior to that of day. The correlation between the field strength of X rate at Hiraiso and the 10μs jumps could not be found at the present time. Some modes of reflecting height in 100kHz were accordance with season, latitude and the direction of the pass route. If the SWC value is decided in fix, these variations will over the accuracy of this system frequently. Consequently, the Loran C SWC tables should be roughly correct by these condition above.
