Radio frequency range between 3-30 MHz is called high frequency or shortwave radio. For a long time, the high frequency band has been considered as the most important means for communications over long distance. The advent of new technologies, such as satellite and terrestrial communications, made the high frequency systems obsolete. Despite that, a new interest for these systems is growing due to the need of having a relatively cheap and simple system for data and voice exchange, which could be a real alternative to existing system in case of their failure. This paper aims to present an effective and flexible HF digital transceiver demonstrator based on the software defined radio paradigma. The purpose of this demonstrator is to maintain the '"essential" information among the authorities in case of the failure of both satellite and Internet communications for critical scenarios (e.g., terroristic attacks, natural disasters).
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