Studies on the OMEGA Navigation System, Trans-Pacific Experiment-II

Abstract

OMEGA trans-Pacific experiments were made by the two ships separetly during fall of 1970 (Fig 1). Using two receivers over the voyage on each ship, the one was for 10.2kHz and the other 13.6kHz respectively, these examinations were carried out. The difference between 10.2kHz and 13.6kHz on the fluctutation range of phase/phase difference could not find clearly, because the micro change of phase in accordance with the moving ship was not obtained easily. The accuracy of the each OMEGA hyperbolic line in the Bering Sea and the Alaska Bay, would be improved within 1nmi without any relation either night or day under normal condition. The fluctuation range of A-C pair in nighttime was more stable than that of daytime. The reason why might be due to the propagation path of Aldra acrossing the Arctic Zone was stable. According to the field strength pattern of Haiku, the following result was obtained that the difference of propagation path such as east or west, and the difference of the attenuation rate in day-and-night pattern was markedly. The transit time of day/night in the waters of the meridian of Haiku was synchronized completely with the diurnal field strength. It was found that the best way to detect SPA under ship moving is to use the record of field strength. The propagation disturbances were observed 55 times during the voyage via Bering Sea, and these continuous time was 2-51 mininutes. These phenomena could be classfied into SID (SPA) and VLF sferics. Some disturbances caused by SPA, in the case of OMEGA System, suggested that the phase lag in phase difference neverthless the phase advances in phase. Most of VLF sferics were occured in the Area 09, especially near Attu Island and Kamchatka Penn. Nearly all of the field strength of Aldra during VLF sferics were observed suddenly change, on the contrary that of Haiku were disturbed sometimes. The relations between magnetic indicies Kp and the sferics did not found. The disturbances excluded the solar flare were presumably to be weak VLF emission and the strong polar atmospherics with the record of the spectrum obtained by a VLF wide band receiver.