Software-defined-radio based ionospheric chirpsounder for self-organizing HF networks
Baliganapalli Nagaraju, Pradeep
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Ionospheric propagation is the basis of long-distance high frequency (HF) communications on frequencies of 2.0 to 30.0 MHz. To successfully establish a robust wireless link between a pair of geographically separated HF transceivers, we need to estimate the maximum usable frequency (MUF) of the wireless link so as to be able to select an operating frequency near the MUF. One means by which this is traditionally achieved is the use of ionospheric chirpsounders 1 . A chirpsounder is typically a linearly varying frequency (LVF) modulator transmitting a swept continuous wave tone so as to traverse the frequency band of interest, which can be as much as the entire HF band of 2.0 to 30.0 MHz, and then receiving and processing it in order to estimate the received signal strength, propagation delay, and multipath spread at different frequencies. In this thesis, I have designed and implemented the algorithm and architecture for a software-defined-radio (SDR)  based chirpsounder. Software defined radio (SDR)  offers the flexibility to rapidly prototype and re-configure chirpsounder operations in real time. The software-defined chirpsounders are believed to have the potential to become core building blocks of advanced self-organizing HF networking systems able to adapt to periodic and aperiodic variations in ionospheric propagation.