Greg Davis Scott Hambleton Jon Holton Chris Johnson Chris Monfredo 5/13/14Rochester Institute of Technology1 P14251 Underwater Acoustic Communication

5/13/14Rochester Institute of Technology2 Project Background Boeing wants to improve it’s relationship with RIT through sponsoring projects that involve students in aquatic engineering challenges. This project is to design a limited bandwidth communication system. The system is to be able to send and receive information as well as have communication protocols that allow for multiple systems to be able to communicate in a swarm. This system is acoustic based. Using a speaker and hydrophone, high frequency signals are to be sent between two watertight modules that are housing the electronics necessary to send and receive meaningful data.

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology3 Project Goals To be able to send a signal 30 meters with high accuracy as quickly as possible. The system should be able to withstand pressures caused by 10 meters of water and should be able to resist corrosion and leaking. The system needs to be easily modified for the purposes of future expansion. The housing should be easily retrofitted to hold either future optical signal systems.

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology4 Customer Needs

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology5 Engineering Specifications

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology6 System Diagram

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology7 Risk Analysis

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology8 Full System Build

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology9 Full System Build

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology10 System Tests Mechanical Watertight Pressure resistance Corrosion resistance Electrical Signal Path Tracing Power Systems PCB Verification Computer FFT Synchronization Error Handling Sending/Receiving Frames

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology11 Results vs Specifications

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology12 State of the Project The system is mostly functional. There are issues with the speaker and the fickle nature of this device has caused numerous problems. The software is functioning in one-way communication, but the code is in place to make it function in two-way. Messages can be sent reliably but at low speeds. The electronics are designed to support 4 FSK and should be easily integrated into future builds. The housing has a leak issue. After an overnight test there was a small amount of water inside the housing.

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology13 Lessons Learned BeagleBone Black vs. Raspberry Pi Automatic Gain Control Pulse Shaping Power Amplifiers PCB Design Hydrophones Power Converter Startup Current 3-D Printing Parabolic Dish Design malloc() Bit Collisions

Underwater Acoustic Communication 5/13/14Rochester Institute of Technology14 Recommendations For Improvements Circuit Board Changes New Acoustic Transmitter Flyback Diodes New FFT Package (FFTW) Better Synchronization Algorithm Fix ADC