Variation of Ionospheric Narrowband and Wideband Performance for a 12,760 km Transequatorial Link and Its Dependence on Solar and Ionospheric Activity

Rosa Ma Alsina-Pagès,Antoni Segarra,Xavier Gonzalez Sans,Estefania Blanch,David Altadill,Marcos Hervás

doi:10.3390/rs12172750

Abstract

The ionosphere provides a channel that is able to propagate electromagnetic waves for long-haul communications, allowing Non-Line-Of-Sight (NLOS) radio communications in the high-frequency band (HF). Nonetheless, its performance as a communications channel mainly depends on solar activity, as Earth’s diurnal and seasonal cycles modify the ionospheric ionization by the sun and consequently the channel performance. La Salle and the Observatori de l’Ebre have conducted oblique soundings of a 12,760 km ionospheric channel from Livingston Island (South Shetland Archipelago—Antarctica −62.7∘S, 299.6∘E) to Cambrils (Spain −41.0∘N, 1.0∘E) to evaluate this evidence and analyze the characteristics of this particular channel. The final goal of the project is to establish a stable communications link to be used as a backup for low throughput data transmission from the various geomagnetic and meteorological sensors located in the Spanish Antarctic Station. The aim of this paper is to confirm the relationship between the channel availability of narrowband and wideband communications and the resulting channel parameters with the solar and ionospheric activity for four consecutive sounding campaigns.

Highlights

The ionosphere is a hostile channel for high-frequency (HF) radio communications due to the several phenomena that constantly change the its performance conditions
This paper studies the potential relationship between solar activity (SSN) and the propagation of a wideband signal in a 12,760 km long haul ionospheric link between Antarctica and Spain
We conclude from the study that the higher the solar activity, the higher the mean value of the composite delay spread and the composite Doppler spread; no significant influence of solar activity is observed in terms of the number of paths in the propagation

Summary

Introduction

The ionosphere is a hostile channel for high-frequency (HF) radio communications due to the several phenomena that constantly change the its performance conditions. The ionization varies considerably depending on the activity of the Sun, and the variations of the solar flux radiation, such as ultraviolet and X-ray radiation, can have significant effects [1]. An awareness of this variation becomes absolutely central when attempting to model a given ionospheric channel for communication purposes [2]. Disturbances related to equatorial plasma bubbles (EPBs) contribute significantly to the ionospheric variability [7] Such disturbances are closely related to the well-known Equatorial Spread-F phenomena [8] (ESF) which are consequences of the diffusive nature of the ionospheric echoes produced by radio scattering from electron density irregularities [9]

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Conclusion