Waveguide Parameters of 19.8 kHz Signal Propagating over a Long Path

Sushil Kumar

doi:10.1155/2009/216373

Abstract

The amplitude and phase of 19.8 kHz signal from navigational transmitter located in North West Cape, Australia, recorded at Suva, Fiji, have been utilized to determine the waveguide mode parameters. The propagation path is mixed over land and sea having Transmitter-Receiver Great Circle Path distance 6.7 Mm. The experimental values of the parameters were found to be consistent with the theoretical values calculated using the mode theory of VLF wave propagation in the waveguide.

Highlights

Low Frequency (ELF: 3–3000 Hz) and Very Low Frequency (VLF: 3–30 kHz) signals propagate to great distances in the waveguide bounded by the Earth’s surface and the lower ionosphere (∼60–140 km), consisting of the D and E-regions
SoftPAL is a state of art data acquisition system recently (2006) developed by AD Instruments, New Zealand, which can log amplitudes and phases of seven MSK VLF transmitter signals continuously with the time resolutions ranging from 10 milliseconds to 10 seconds, using a GPS based timing
The daytime signal strength is larger than the nighttime which could be mostly due to the higher attenuation of Earth-Ionosphere Waveguide (EIWG) for the daytime VLF propagation [8]

Summary

Introduction

Low Frequency (ELF: 3–3000 Hz) and Very Low Frequency (VLF: 3–30 kHz) signals propagate to great distances in the waveguide bounded by the Earth’s surface (ground or sea) and the lower ionosphere (∼60–140 km), consisting of the D and E-regions. This atmospheric waveguide is known as the Earth-Ionosphere Waveguide (EIWG). Clilverd et al [6] have presented some interesting long-term (1990–1995) studies of VLF propagation over a long North-South path from Cutler (USA), Marine (NAA transmitter, 24 kHz) to Faraday, Antarctica They found the timings of the minima in the received signal strength to be remarkably consistent from year to year. The 1-minute averaged amplitude and phase data recorded at 0.1 second have been used for analysis

Theoretical Background

Observational Data and Results

60 TRGCP in light

Conclusions