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Today many types of communication are employed on seagoing vessels, such as radio, satellite and Wi-Fi but only one type of communication is practical for submerged vessels, the acoustic underwater modem. The "off-the-shelf" modems are sometimes difficult to update and replace, especially on a large submarine. But by separating the hardware from the signal processing and making the software modular more versatility can be achieved.   The questions that this thesis are asking are: is it possible to implement the signal processing in software? How small or large should the modules be? What kind of architecture should be used? This thesis shows that it is indeed possible to implement simple algorithms that can isolate a signal and read its content regardless of the hardware configuration. Calculations show that up to 13 kbps can be reached at a range of one kilometer. It is most practical to make the entire physical layer into one module and the size of the system could drastically change the type of architecture used.

VDSL2 is the fastest xDSL technology at present. Its data rate is variable depending on the length of wire and generally higher than HDSL and VDSL. VDSL2 uses the original POTS hardware to provide up to 100 Mbps data rate in upstream and downstream. The disadvantage of VDSL2 is that the longer the transmission distance, the lower the data rate. Generally speaking, the transmission distance is typically less than 1200 meters. The VDSL2 modem in this research is based on Infineon chip set composed of PEB83000 and ADM5120 with an operating band up to 30 MHz. The data rate in the different profiles of chip set is compared to find the optimum performance for a certain transmission distance.

Orientador: Rege Romeu Scarabucci / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica / Made available in DSpace on 2018-07-23T20:57:36Z (GMT). No. of bitstreams: 1 Portelinha_FranciscoMartins_M.pdf: 8195773 bytes, checksum: d5185d4b47aa02871f2cdf527d0bf93f (MD5) Previous issue date: 1994 / Resumo: Este trabalho apresenta uma nova técnica de processamento puramente digital para realizar as funções de modulação e demodulação QPSK (Quadrature Phase Shift Keying). Um protótipo experimental foi realizado e as medidas de desempenho mostraram resultados satisfatórios, compatíveis com desempenho obtidos através de outras implementações físicas / Abstract: Not informed. / Mestrado / Mestre em Engenharia Elétrica

[pt] Uma solução simples, de baixo custo e robusta, para o problema de multipercursos na comunicação acústica submarina em águas profundas, é apresentada. Inicialmente, uma caracterização do perfil de atrasos e do nível de ruído, em ambientes de exploração de petróleo Offshore é feita, com o objetivo de definir as características do canal de comunicação em questão. A técnica de modulação, considerada mais adequada pela sua simplicidade e robustez, é a FSK. A inadequação de um sistema FSK-2 não coerente, sem nenhuma medida contra o multipercurso é comprovada em resultados experimentais. Duas possíveis soluções para o problema de demodulação de sinais FSK-2 com multipercurso são apresentadas. Uma muito simples, baseada na inserção de tempos de guarda entre dois bits, suficientes para o desaparecimento dos multipercursos, que foi implementada e testada. A outra, mais elaborada, baseada na estimação dos parâmetros do canal, através do algoritmo EM, e da análise de particularidades do problema para o caso de três raios. Essa segunda solução é analisada e simulada em computador. Os resultados para as duas soluções são analisados. / [en] A simple, low-cost and robust for the problem of multipath in underwater acoustic communication in deep water, is presented. Initially, a delay profile and noise level characterization, in offshore oil exploitation environments is done, with the objective of defining the communication channel of interest. The modulation techique, considered adequate by means of its simplicity and robustness is FSK. The non adequacy of an non-coherent FSK-2 system, without any contermeasure againt multipath is showed in experimental results. Two possible solutions to the problem of the demodulation of FSK-2 signals with multipath are presented. One very simple, based on the insertion of guard times between the bits, sufficient to the vanishing of the multipaths, that have been implemented and tested. The other, more elaborated, based in the estimation of the channel parameters, with the EM algorithm, and the analysis of some particularities of the problem, for the case of three rays. The second solution is analyzed and simulated in a computer. The results for both solutions are analyzed.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Shrinking budgets and labor pools have impacted our ability to perform experiments at the Nevada Test Site (NTS) as we did previously. Specifically, we could no longer run heavy cables to remote data acquisition sites, so we replaced the cables with RF links that were transparent to the existing system, as well as being low-cost and easy to deploy. This paper details how we implemented the system using mostly commercial off-the-shelf components.

<p>Westermo Teleindustri tillverkar och säljer telefonmodem för industritillämpningar och ska erbjuda ett konfigureringsverktyg till dessa. Verktyget ska konfigurera Westermos modem med Hayes AT-kommandon genom ett PC program som ska vara enkelt att använda så att deras supportavdelning blir avlastad från en del konfigureringssupport. Min uppgift i detta examensarbete var att ta fram en kravspecifikation och implementera en lösning utifrån denna. Kravspecifikation togs fram genom att skicka ut förfrågningar om önskemål till dotterbolag, distributörer och andra som har nära kontakt med slutkunderna. I kravspecifikationen beskrivs vilken funktionalitet programvaran skall innehålla. Att göra en design av en programvara kräver att man har kunskaper om språket och verktygen som ska användas för implementationen. Verktyget som Westermo tillhandahåller för att implementera Windows applikationer är MFC(Microsoft Foundation Class) som är en instans i Microsoft Visual Studio 6.0. MFC är ett bibliotek av klasser som underlättar Windows API användningen för programmeraren. Det är alltså som ett skal för programmeraren vilket gör att implementationen går snabbare. En design gjordes innan implementeringen av verktyget började. En viktig detalj i programmet är att nya produkter ska kunna utnyttja programvaran, dvs. den ska vara utvecklingsbar och kunna uppdateras för nya modem. Detta görs genom att läsa in hur modemet ska konfigureras genom vanliga textfiler som beskriver hur modemet ska konfigureras. Detta innebär att ett nytt modem endast kräver ett par nya textfiler och medför ingen omkompilering av programmet.</p>

The thesis is focused on designing OFDM modem, which should be implemented into the FPGA device. The advantages of using OFDM signals in order to provide high baud rates together with high multipath immunity has provoked a mass expansion into media systems such as DSL, DVB, Wi-Fi, WLAN, etc. . Thanks to this technology we can quarantee high modulation rates with minimal negative disturbance eects. The rst part is dedicated to characterise OFDM signals, their generation and the algorithm producing the OFDM which is implemented in DSP devices. For the purpose of using the fastest algorithm, the Fast Fourier Transform using Cooley-Tukey algorithm was shown. Before we can implement OFDM modem into the FPGA device, we have to simulate its correct function. Because there is no OFDM analyser available at our departement, its necessary to prove its correct function by simulations. Therefore a large part of this thesis is focused on simulations using Matlab and ModelSim, in order to show comparison between the theoretical, and simulated results. Between the theoretical and practical simulations there is a part which shows the brief characteristics of available FPGA devices. Detailed view is presented just for the Virtex II device, which the implementation is made for. As a suitable FPGA device, we have chosen Virtex II XC2V1000 which is available for students. In the last part the measured results were shown to prove the corect function of the modem. Programming the FPGA using VHDL language is realized in the software ISE Xilinx (distributed in Xilinx software support). All programmed scrits and data used in this thesis are included on distributed media.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / This paper describes the design and successful development of an acoustic modem for potential use in underwater ecological sensor networks. The presentation includes theoretical study, design and development of both software and hardware, laboratory experiments, full-scale field tests, and the documentation and analysis of field-test results.

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / As the integrated Network Enhanced Telemetry (iNET) program moves forward in resolving systems engineering design and architecture definition, critical technology “gaps” and a migration path to realizing the integration of this technology are needed to insure a smooth transition from the current legacy point to point telemetry links to a network oriented telemetry system. Specifically identified by the DoD aeronautical telemetry community is the need for a migration to a network solution for command, control, and transfer of test data by optimizing the physical, data link, and network layers. In this paper, we present a network centric telemetry preliminary architecture approach based on variants of 802.11 that leverages the open standards as well as the previous Advanced Range Telemetry (ARTM) work on the physical layer waveform. We present a burst modem approach based on the recent AOFDM 802.11a work, a TDMA-like MAC layer based on 802.11e, and then add additional MAC layer features to allow for the multi-hop aeronautical environment using a variant of the current working standard of 802.11s. The combined benefits of the variants obtained from 802.11a, 802.11e, and 802.11s address the needs for both spectrum efficiency in the aeronautical environment and the iNET program.