Baseband signal processing with UnetStack

Software-defined underwater modems implement key components of an underwater communication system in soft-ware, 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.