Experimental VLF relative navigation on R/V Atlantis II, cruise 15

Abstract

An experimental long-range relative navigation system was employed on the Research Vessel ATLANTIS II of the Woods Hole Oceanographic Institution during Cruise 8 to the Indian Ocean in 1963 and Cruise 15 which circumnavigated the globe in 1965. The very low frequencies (VLF) transmitted by stations having stab1lized carriers (a few part s in 10 11) can be received throughout the world. Navigational information is obtained from the comparison of the received signals of two or more stations with a precision oscillator which serves as a reference. Geographical changes result in phase changes which may be computed to longitude and latitude if the starting point is known; thus, the system is relative. Reference points could be supplied to the VLF system from a satellite radio navigator that was loaned to the U.S. Navy for this cruise. Best positioning agreed to within three nautical miles from best ship's position under favorable conditions. The VLF equipment also was able to provide (l) a measure of ship's drift on station, (2) precise time and frequencies, and (3) a means for calibrating the ship's EM log at sea.