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Software Defined Acoustic Underwater Modem
Today many styles of conversation are employed on  what is 0x0 0x0 error   seagoing vessels, such as radio, satellite and Wi-Fi however most effective one form of verbal exchange is sensible for submerged vessels, the acoustic underwater modem. The ”off-the-shelf” modems are occasionally difficult to replace and update, mainly on a massive submarine. But by keeping apart the hardware from the signal processing and making the software modular greater versatility may be executed. The questions that this thesis are asking are: is it viable to implement the signal processing in software? How small or huge have to the modules be? What kind of structure need to be used? This thesis shows that it is certainly feasible to put in force easy algorithms which can isolate a signal and read its content material irrespective of the hardware configuration. Calculations display that as much as 13 kbps can be reached at a range of one kilometer. It is maximum realistic to make the complete bodily layer into one module and the size of the machine may want to considerably exchange the sort of structure used. 1 Preface This Master’s thesis from Jakob Lindgren is the final venture for receiving the Master’s degree in Robotics at M¨alardalen University in V¨aster˚as, Sweden. It covers the basics of digital communication inside the underwater channel as properly as some easy algorithms for software program defined communication. The purpose of this master thesis is to research how a software defined acoustic underwater verbal exchange can be carried out. This work was executed at Saab Underwater Systems in Motala, Sweden, all through the autumn term of 2010. I hope this thesis can growth your information of communications and software program layout and with any luck you will put this document away with extra solutions than questions. I would also like to take this opportunity to thank my thesis marketing consultant, Ola Pettersson, for the assist, questions and laughs given throughout this work. 2 Contents 1 Introduction 5 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Project objectives and obstacles . . . . . . . . . . . . . . . . 7 2 Acoustic underwater verbal exchange 8 2.1 Network protocol shape . . . . . . . . . . . . . . . . . . . . Eight 2.2 Acoustic underwater modem . . . . . . . . . . . . . . . . . . . 10 2.Three Software driven modem . . . . . . . . . . . . . . . . . . . . . . 10 2.Four Underwater channel . . . . . . . . . . . . . . . . . . . . . . . . 10 2.Five Constellation diagrams . . . . . . . . . . . . . . . . . . . . . . 12 2.6 Channel outcomes . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.6.1 Effect of noise . . . . . . . . . . . . . . . . . . . . . . . 13 2.6.2 Coherent vs non-coherent . . . . . . . . . . . . . . . . 14 2.6.3 Signal electricity and Doppler impact . . . . . . . . . . . . 15 2.6.Four Echoes . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.7 Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.7.1 Why modulate . . . . . . . . . . . . . . . . . . . . . . 17 2.7.2 Digital modulation . . . . . . . . . . . . . . . . . . . . 17 2.7.3 Benefits and disadvantages . . . . . . . . . . . . . . . . . . 22 2.Eight Demodulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.Nine Orthogonal frequency division multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.10 Error correcting and interleaving . . . . . . . . . . . . . . . . 27 3 Implementation 30 three.1 Physical layer structure . . . . . . . . . . . . . . . . . . . . . . 30 3.2 Structure of the implementation . . . . . . . . . . . . . . . . . 32 three.3 Envelope detector . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.4 Modulator and demodulator implementation . . . . . . . . . . . . . . . . . . . . . . . . . . 36 three.Four.1 Processing incoming waveform . .

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