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Chris Monfredo Chris Johnson Jon Holton Greg Davis Scott Hambleton

P14251 Underwater Acoustic Communication. Chris Monfredo Chris Johnson Jon Holton Greg Davis Scott Hambleton. 10/03/13. Rochester Institute of Technology. 1. Underwater Acoustic Communication. Agenda Revisit Customer and Engineering Requirements Functional Decomposition

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Chris Monfredo Chris Johnson Jon Holton Greg Davis Scott Hambleton

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  1. P14251 Underwater Acoustic Communication Chris MonfredoChris JohnsonJon HoltonGreg DavisScott Hambleton 10/03/13 Rochester Institute of Technology 1

  2. Underwater Acoustic Communication • Agenda • Revisit Customer and Engineering Requirements • Functional Decomposition • Morphological Charts • Morph Details • Pugh Analysis • Final Pugh Analysis • Final System Selection • Risk Analysis • Test Plans • Subsystem Design Schedule 10/03/13 Rochester Institute of Technology 2

  3. Underwater Acoustic Communication • Customer Requirements • Most important requirements: 10/03/13 3 Rochester Institute of Technology

  4. Underwater Acoustic Communication • Engineering Requirements • Most important requirements: 10/03/13 Rochester Institute of Technology 4

  5. Underwater Acoustic Communication Functional Decomposition 10/03/13 Rochester Institute of Technology 5

  6. Underwater Acoustic Communication System Flow Diagram 10/03/13 Rochester Institute of Technology 6

  7. Underwater Acoustic Communication Communication Protocols: ALOHA • Easy to Implement • Inefficient – Theoretical throughput of 18% (36% for slotted ALOHA) • Better suited for long distances 10/03/13 Rochester Institute of Technology 7

  8. Underwater Acoustic Communication Communication Protocols: CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) • Less Noise • Better Throughput • Can function with swarm expansions • Terminal Problems vs. Overhead 10/03/13 Rochester Institute of Technology 8

  9. Underwater Acoustic Communication Communication Protocols: CDMA(Code Division Multiple Access) - Sends data in a unique frequency pattern - Receiver can intercept multiple signals and decode based on the pattern - Allows multiple, simultaneous senders with same set of frequencies • Widely-Used by 2G and 3G Devices • High Throughput • Difficult to Implement • Difficult to test – Requires more than two devices 10/03/13 Rochester Institute of Technology 9

  10. Underwater Acoustic Communication • Error Detection and Correction Detection Methods: • Parity Bits • Cyclic Redundancy Checks (CRCs) • Error Correcting Code (EEC) Correction Methods: • Automatic Repeat Requests (ARQs) • Forward Error Correction (FEC) • Hybrid Schemes (Both ARQ and FEC) 10/03/13 Rochester Institute of Technology 10

  11. Underwater Acoustic Communication • Encryption and Compression • Encryption Methods: • Triple DES (56-bit) • AES (128-bit) • If not enough time, something simple (XOR the bit stream) Compression Methods: • Lossless Algorithms • Lossy Algorithms 10/03/13 Rochester Institute of Technology 11

  12. Underwater Acoustic Communication • Computational Power Microprocessors: • Low Price • Low Complexity • Efficient • Fairly Versatile • Many microprocessors to choose from Other options (regular processors, FPGAs, ASICs) are too expensive, complicated, and far beyond the scope of this project. 10/03/13 Rochester Institute of Technology 12

  13. Underwater Acoustic Communication Rochester Institute of Technology • Power Converters • Transformer • High voltage step-down or positive and negative voltage • Buck Converter • High efficiency step-down • Linear Regulator • Easy to implement but low efficiency 10/03/13

  14. Underwater Acoustic Communication Rochester Institute of Technology • Amplitude Modulation • Easy to Implement • Requires more power than other schemes • Carrier frequency must be about 10X data rate 10/03/13

  15. Underwater Acoustic Communication Rochester Institute of Technology • Frequency Modulation • Susceptible to frequency shifts due to Doppler effect or sound speed changes • Carrier frequency is move flexible than AM 10/03/13

  16. Underwater Acoustic Communication Rochester Institute of Technology • Phase Shift Keying • Harder to implement than FM but more resistant to noise • More bandwidth efficient than FM 10/03/13

  17. Underwater Acoustic Communication Rochester Institute of Technology • Quadrature Amplitude Modulation • Hardest to implement • Can encode the most amount of information • Susceptible to noise 10/03/13

  18. Underwater Acoustic Communication • Water Resistance • Gasket/O-rings • Caulk/Sealant • Tight Fit Pressure Resistance • Structural Strength/Case Design • Internal Pressurization • Corrosion Resistant • Material Selection • Metals • Plastics • Corrosion Resistant Coating • Barrier • Galvanization 10/03/13 Rochester Institute of Technology 18

  19. Underwater Acoustic Communication • Dissipate Heat • Heat sink • Fan • Liquid cooling • Use external water • Use internal system Image from: http://en.wikipedia.org/wiki/File:Heatsink_povray.png 10/03/13 Rochester Institute of Technology 19

  20. Underwater Acoustic Communication Morphological Chart 10/03/13 Rochester Institute of Technology 20

  21. Underwater Acoustic Communication Pugh Analysis 10/03/13 Rochester Institute of Technology 21

  22. Underwater Acoustic Communication • Finalized Pugh Analysis • Generation of hybrid between two best systems 10/03/13 Rochester Institute of Technology 22

  23. Underwater Acoustic Communication Final System Selection 10/03/13 Rochester Institute of Technology 23

  24. Underwater Acoustic Communication Risk Analysis Major Concerns: Speaker, Data Loss, and Carrier Frequency Loss Minor Concerns: Power Surge, Short Circuiting, Watertight Case, and Bad Parts 10/03/13 Rochester Institute of Technology 24

  25. Underwater Acoustic Communication • Test Plans • ASTM B117-11 Salt Spray Test • IPX7 Submersion Testing • Operating Temperature Testing • Error Correction Testing 10/03/13 Rochester Institute of Technology 25

  26. Underwater Acoustic Communication Subsystem Design Schedule 10/03/13 Rochester Institute of Technology 26

  27. Underwater Acoustic Communication Questions? 10/03/13 Rochester Institute of Technology 27

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