New Measurements of Phase Velocity at VLF

Abstract

The purpose of this note is to describe some new phase velocity measurements using signals from the VLF stations NPG (18.6 kc/s) near Seattle, Wash., and WWVL (20.0 kc/s) near Fort Collins, Colo. Previous experimental results have been described by Wait [1961].

Distribution of standard frequency and time signals

“…The National Aeronautics and Space Administration has reported interest in this VLF time distribution system for use at its satellite tracking stations [35]. Further investigations of its utility as a worldwide accurate time distribution system are underway at NBS [36] and elsewhere [37], [38]. Another similar system for VLF distribution of time signals has been reported [39], [40].…”

“…As mentioned before, the multiple carrier VLF technique devised by NBS [32], [14], [34], possibly a similar one under study in Italy, [39], [40], and the Omega System appear to be promising for the worldwide distribution of SFTS, as shown by theoretical [14], [39], [40] and experimental studies [34], [36]- [38]. The technical and economic advantages of such a system are: 1 ) it requires a relatively narrow bandwidth; 2) it will provide continuous and worldwide signals for clock synchronization and time interval requirements; 3) the transmissions are from a single site (a suitable backup in cases of emergency may be provided at another site) and therefore it does not have the transmitter synchronization problems inherent in other possible worldwide systems; 4) the reliability and continuity of its signals at a receiver will be many times greater than that of a network of transmitters that must be kept accurately synchronized at all times if the timing signals are to be useful ; and 5) the cost of operating and maintaining a single transmitting station would obviously be much less than that of a network.…”