SimpleModem: A Low Cost Acoustic Modem Implementation for In-Situ Sensing Applications

SimpleModem is a simple, low-cost, modular modem architecture designed for use with many different acoustic actuators for the marine sensing research and hobbyist communities. Dense in-situ sensing networks require large numbers of low-cost communication systems that integrate seamlessly with arbitrary sensor, actuation and power systems. SimpleModem's easy-to-learn architecture will enable future development of a wide variety of such sensor systems. SimpleModem implements a 430/360 Hz frequency-shift keying (FSK) Protocol, encoded via a simple assembly language routine and decoded using an array of operational amplifiers; a complete explanation of firmware and signals analysis is included herein. Schematics for the full system, along with the simple low-level programs are provided. The SimpleModem architecture is designed to work with future interchangeable acoustic actuators, enabling communication through water, air and high density sediments.