Underwater acoustic modem with streaming video capabilities

Oceans have shown tremendous importance and impact on our lives. Thus the need for monitoring and protecting the oceans has grown exponentially in recent years. On the other hand, oceans have economical and industrial potential in areas such as pharmaceutical, oil, minerals and biodiversity. This demand is increasing and the need for high data rate and near real-time communications between submerged agents became of paramount importance. Among the needs for underwater communications, streaming video (e.g. for inspecting risers or hydrothermal vents) can be seen as the top challenge, which when solved will make all the other applications possible. Presently, the only reliable approach for underwater video streaming relies on wired connections or tethers (e.g. from ROVs to the surface) which presents severe operational constraints that makes acoustic links together with AUVs and sensor networks strongly appealing. Using new polymer-based acoustic transducers, which in very recent works have shown to have bandwidth and power efficiency much higher than the usual ceramics, this article proposes the development of a reprogrammable acoustic modem for operating in underwater communications with video streaming capabilities. The results have shown a maximum data-rate of 1Mbps with a simple modulation scheme such as OOK, at a distance of 20 m.

Hermes: um software-modem ADSL baseado no framework Ptolemy II

Esta dissertação tem como objetivo principal apresentar a implementação de um software-modem ADSL totalmente escrito em Java, utilizando o framework Ptolemy II, denominado de Hermes (de "A Handy Experimental Software Modem System"). Um software-modem é útil em ocasiões onde se precisem executar testes e simulações de sistemas de comunicação com um número grande de modens e quando os parâmetros desses sistemas precisem ser modificados com um alto grau de liberdade. Além disso, um software-modem possui características que tornam mais fácil a tarefa de acrescentar, eliminar, validar e analisar funções e algoritmos de processamento de sinais e de telecomunicações. Testes e simulações foram realizados para analisar a funcionalidade do Hermes, utilizando, inclusive, o Tracespan, um equipamento para análise não-intrusiva de redes DSL. A partir dos resultados obtidos em conjunto com o Tracespan, foi possível validar com sucesso as funções do Hermes.

Alocação de modem PLC utilizando SNR em uma rede elétrica de baixa tensão

Pós-graduação em Engenharia Elétrica - FEIS

Optimization of Arq Parameters of Stanag 5066 for the HFDVL Modem

The reliability of bidirectional communication link can be guaranteed with Automatic Repeat Request Procedures (ARQ). The standard STANAG 5066 describes the ARQ procedure for HF communications that can either be applied to existing HF physical layers modems or adapted to future physical layer designs. In this contribution the physical layer parameters of an HF modem (HFDVL), developed by the authors over the last decade, are chosen to optimize the performance of the ARQ procedure described in STANAG 5066. Besides the interleaving length, constellation size and coding type, the OFDM-based HFDVL modem permits the selection of the number of receiver antennas. It will be shown that this parameter gives additional degrees of freedom and permits reliable communication over low SNR HF communication links.

Direct support and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools) : modem, telephone P TA-219/U, FSN 5805-503-1062.

"August 1974."

Operator's and organizational maintenance manual : modem, cable driver, MD-1025/G, (NSN 5820-01-145-4905).

Includes index.

Organizational maintenance : modem radio teletypewriter MD-522/GRC, (NSN 5815-00-999-5277).

Includes index.

Operator's manual : modem radio teletypewriter MD-522A/GRC, (NSN 5815-00-919-4800).

"5 April 1984."

Operator's and organizational maintenance manual : modem, cable driver, MD-1024/G (NSN 5820-01-145-4902).

Includes index.

Operator's manual : modem radio teletypewriter, MD-522/GRC (NSN 5815-00-999-5277).

Includes index.

Organizational maintenance : modem radio teletypewriter MD-522A/GRC (NSN 5815-00-919-4800).

Includes index.

Direct support and general support maintenance : modem radio teletypewriter MD-522A/GRC (NSN 5815-00-919-4800).

"11 May 1984."

Direct support and general support maintenance repair parts and special tools lists ... for radio teletypewriter, modem MD-522A/GRC (NSN 5815-00-919-4800).

"June 1979."