This paper explored the development of software-defined radio (SDR) based alternative positioning, navigation and timing (PNT), independent of any Global Navigation Satellite System (GNSS) for use in GNSS-denied areas. A navigation signal architecture based on GPS L1C signal was designed and broadcasted on a network of SDR-based transmitters. Signals were processed by a moving receiver which used a MATLAB-based software receiver to successfully estimate changes in range to each of the transmitters.
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