Baseband Signal Processing with UnetStack

Software-defined underwater modems implement key components of an underwater communication system in software, rather than hardware, and allow engineers and researchers to modify those components dynamically. These components include not only high-level network protocols, but also physical layer signal processing chains, modulation techniques and error-correction codes. The UnetStack project provides a flexible platform for software-defined open-architecture underwater modems and networks. We outline the software-defined modem functionality in UnetStack that enables users to process baseband acoustic signals directly. We demonstrate several practical applications of baseband signal processing, including an implementation of a software-defined OFDM modem, a delay-Doppler channel estimator, and an underwater vehicle to transponder range estimator.