International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In response to a NASDA decision to upgrade their satellite ground network (GN) to provide worldwide coverage as well as interoperability with other agencies, MELCO has assembled remote ground stations that include the L-3 Communications Telemetry & Instrumentation (L-3 T&I) NETstar 20001 TT&C system. Software developed by Mitsubishi Electric Corporation (MELCO) controls a variety of COTS products in the remote stations, including the L-3 T&I system. L-3 T&I’s TT&C system provides modem services, high accuracy ranging, Doppler compensation, command verification, and CCSDS protocol processing for a wide range of LEO/MEO/GEO satellites.

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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Vehicle tracking system based on GPS has been paid more and more attention. The system consists of GIS (Geological Information System), master station, movable station and communication network. Movable stations installed on automobiles transmit their position and status messages to the master station. All vehicles' tracks are drawn on the electrical map displayed by the master station's computer screen in real time. Vehicles' alarming signals can also be transmitted to the master station simultaneously. This paper presents a whole designing scheme of the vehicle tracking system, then it makes a thorough introduction to the system's performance and working procedure. The key technologies employed by the system and the relations between them are also discussed in details in the paper.

The ease with which indoor wireless systems can be installed has become their main selling feature. A desirable application for wireless systems is the transmission of compressed digital music in an indoor shopping mall environment. The indoor environment, with its many walls and highly reflective surfaces, has a high level of multipath. High levels of slowly changing multipath can cause deep fades, and therefore reduce the reliability of the system. <p> The proper use of multiple receiving elements is one way to mitigate the deep fades caused by multipath. The main objective of this thesis is to study a simple and cost effective approach to combining the signals from several receiving elements. A novel diversity combining approach using 2 receiving elements is presented. The novel diversity combining approach consists of periodically changing the phase of one of the two received signals. <p> A set of simulations was developed to study the effectiveness of the novel diversity combining method in mitigating deep multipath fades. The relative performances of two different implementations of the diversity combining were compared to a baseline test case that did not include diversity combining. In both of the simulated implementations, the diversity combining approach proved to be an effective means of mitigating the multipath fading phenomenon. <p> A proof-of-concept, bench-top hardware prototype was also developed. The transmitter and receiver were implemented in Field Programmable Gate Arrays (FPGAs). The laboratory testing of the hardware successfully illustrated the feasibility of the proof-of-concept system.

The ease with which indoor wireless systems can be installed has become their main selling feature. A desirable application for wireless systems is the transmission of compressed digital music in an indoor shopping mall environment. The indoor environment, with its many walls and highly reflective surfaces, has a high level of multipath. High levels of slowly changing multipath can cause deep fades, and therefore reduce the reliability of the system. <p> The proper use of multiple receiving elements is one way to mitigate the deep fades caused by multipath. The main objective of this thesis is to study a simple and cost effective approach to combining the signals from several receiving elements. A novel diversity combining approach using 2 receiving elements is presented. The novel diversity combining approach consists of periodically changing the phase of one of the two received signals. <p> A set of simulations was developed to study the effectiveness of the novel diversity combining method in mitigating deep multipath fades. The relative performances of two different implementations of the diversity combining were compared to a baseline test case that did not include diversity combining. In both of the simulated implementations, the diversity combining approach proved to be an effective means of mitigating the multipath fading phenomenon. <p> A proof-of-concept, bench-top hardware prototype was also developed. The transmitter and receiver were implemented in Field Programmable Gate Arrays (FPGAs). The laboratory testing of the hardware successfully illustrated the feasibility of the proof-of-concept system.

Abstract Along with the increasingly developed computer technology and the wide application of Internet, the use of Internet has been more and more diverse. The function of narrowband network that was limited in the transmission of texts and basic graphs cannot meet the needs of the transmission of multimedia which is consisted of audio, data, video, etc. Therefore, the broadband network has gradually become the mainstream of the network application. The objectives of this study are to discuss the technologies commonly applied in broadband network and to find out how the function of broadband network could be promoted in Taiwan. This study is an industrial policy research. The comparative analysis was conducted on the secondary data collected from both domestic and foreign sources. As shown by the statistics, the number of broadband subscribers has been increasing rapidly in both domestic and foreign areas. This reflects the rising demand of broadband. The conclusions of the study are as follows: 1. The government policy and the industry support make the number of broadband subscriber increase sharply. 2. ADSL and Cable Modem are the technologies commonly adopted among various countries. 3. The economy factor is the primary consideration in adopting the broadband technologies. 4. The content of network is the key factor to the popularity of broadband network. 5. The popularity of broadband network will promote the electronic commerce. There are five suggestions in this study: 1. To install a full optical-fiber network. 2. To accelerate the network into the Internet Protocol one. 3. To cultivate the software professionals. 4. To rationalize the fee of broadband network. 5. To implement the policy on speeding up the construction of broadband network. Key word: Internet, Broadband network, ADSL, Cable Modem

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.

Orientador: Rui Fragassi Souza / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Campinas / Made available in DSpace on 2018-07-18T02:31:27Z (GMT). No. of bitstreams: 1 Scavasin_DecivalA.W_M.pdf: 3912218 bytes, checksum: 5271d0da06796ee9a9f1d81b1731447b (MD5) Previous issue date: 1981 / Resumo: Este trabalho faz parte de um programa de estudo e desenvolvimento de um sistema de transmissão e recepção de sinais digitais via rádio, atualmente em andamento no Departamento de Engenharia Elétrica da Faculdade de Engenharia de Campinas da UNICAMP. Neste trabalho são apresentados os estudos e a implementação de um modulador e de um demodulador PSK de quatro fases (MODEM 4-PSK), além do conjunto de circuitos auxiliares correspondentes (circuito conversor de nível, filtros e circuito de recuperação de portadora). Inicialmente é feita uma comparação entre diversos tipos de modulação e demodulação mais comuns e, em seguida, passa-se à descrição e implementação do MODEM 4-PSK em detalhes. No final são apresentadas as medidas da taxa de erros em função da relação portadora/ruído / Abstract: Not informed / Mestrado / Mestre em Ciências

<p> A simple and relatively inexpensive equalizer has been developed in conjuction with a FSK modulator and demodulator (modem) for the transmission of digital data over time dispersive channels. </p> <p> The transmitter structure consists of a digital modulator followed by two filters, the first of which is a binary transversal filter (BTF), the second a conventional two-stage R-C low-pass filter. </p> <p> In the receiver structure a phaselock loop (PLL) is employed as a discriminator. Synchronization is achieved with a digital phaselock loop (DPLL). Considerable attention is placed on the error rate optimization of the receiving structure. </p> <p> The equalizer uses binary transversal filter comprising a tapped delay line, realized by a long string of metal-oxide semiconductor (MOS) flipflops, with a variable gain circuit associated with each tap in the delay line. The operation of the equalizer is adaptive in that the tap gains are adjusted rom the received data, consequently the tap gains are continually optimized. The algorithm employed for setting the tap gains is simple and can be quite easily implemented using a combination of analog and digital techniques. </p> <p> Experimental results are presented which illustrate the important features of the system implemented under a variety of operating conditions. </p> / Thesis / Master of Engineering (MEngr)

Approved for public release; distribution is unlimited / In the past ten years reliable high-speed satellite systems have pushed slower less reliable communication systems to the bottom of the list for development programs. Concern over reduced budgets, vulnerability of expensive satellite systems, and recent advances in HF technology are creating new interest in upgrading existing HF communication systems. Nondevelopment Items (NDI) are defined as the use of off-the-shelf commercial items instead of costly, time-consuming conventional research and development programs. The Navy Department's current policies are designed to insure the maximum use of NDI to fulfill Navy requirements. The speed of HF systems can be improved using current signaling and modulation techniques, and reliability can be increased by error-correcting codes or error detection used in conjunction with automatic repeat request (ARQ) schemes. Improved HF systems not only provide survivable back-up capability, but increased capacity for present communication needs. / http://archive.org/details/longhaulcommunic00elli / Lieutenant, United States Navy