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Measurement of the Impulsive Noise Environment for Satellite-Mobile Radio Systems at 1.5 GHz.Button, Mark D., Gardiner, John G., Glover, Ian A. January 2002 (has links)
No / Noise amplitude distribution measurements relevant to%satellite-mobile radio systems are reported. The rationale for the%measurements is outlined and the choice of measurement parameters%justified. The measurement equipment and measurement methodology are%described in detail. Results characterizing the elevation angle%distribution of impulsive noise are presented for rural, suburban and%urban environments and also for an arterial road (U.K. motorway)%carrying high density, fast moving traffic. Measurements of the levels%of impulsive noise to be expected in each environment for high- and%low-elevation satellite scenarios using appropriate antenna%configurations are also presented
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SatNEx: A Network of Excellence Providing Training in Satellite CommunicationsSheriff, Ray E., Hu, Yim Fun, Chan, Pauline M.L., Bousquet, M., Corazza, G.E., Donner, A., Vanelli-Coralli, A., Werner, M. 2005 May 1930 (has links)
Yes / Satellite communications represents a specialised area of telecommunications. While the development of satellite technology is relatively slow in comparison to wireless networks evolution, due to the need for high reliability, the services that satellites are able to offer are evolving at much the same pace as their terrestrial counterparts. It is within this context that the satellite communications network of excellence (SatNEx) has evolved its initiative, the aim being to serve the engineering community with the latest technological trends, while also providing a solid grounding in the fundamentals for those new to the subject area. / European Commission Framework Programme 6
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Development of a satellite communications software system and scheduling strategyGilmore, John Sebastian 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Stellenbosch University and the Katholieke Universiteit Leuven has a joint undertaking
to develop a satellite communications payload. The goals of the project are:
to undertake research and expand knowledge in the area of dynamically configurable
antenna beam forming, to prove the viability of this research for space purposes and
to demonstrate the feasibility of the development in a practical application.
The practical application is low Earth orbit satellite communication system for
applications in remote monitoring. Sensor data will be uploaded to the satellite,
stored and forwarded to a central processing ground station as the satellite passes
over these ground stations. The system will utilise many low-cost ground sensor
stations to collect data and distribute it to high-end ground stations for processing.
Applications of remote monitoring systems are maritime- and climate change
monitoring- and tracking. Climate change monitoring allows inter alia, for the monitoring
of the effects and causes of global warming.
The Katholieke Universiteit Leuven is developing a steerable antenna to be
mounted on the satellite. Stellenbosch University is developing the communications
payload to steer and use the antenna. The development of the communications
protocol stack is part of the project. The focus of this work is to implement the
application layer protocol, which handles all file level communications and also implements
the communications strategy.
The application layer protocol is called the Satellite Communications Software
System (SCSS). It handles all high level requests from ground stations, including
requests to store data, download data, download log files and upload configuration
information. The design is based on a client-server model, with a Station Server
and Station Handler. The Station Server schedules ground stations for communication
and creates a Station Handler for each ground station to handle all ground
station requests. During the design, all file formats were defined for efficient ground
station-satellite communications and system administration. All valid ground station
requests and handler responses were also defined.
It was also found that the system may be made more efficient by scheduling
ground stations for communications, rather than polling each ground station until
one responds. To be able to schedule ground station communications, the times
when ground stations will come into view of the satellite have to be predicted. This
is done by calculating the positions of the Satellite and ground stations as functions
of time. A simple orbit propagator was developed to predict the satellite distance
and to ease testing and integration with the communications system. The times
when a ground station will be within range of the satellite were then predicted and a
scheduling algorithm developed to minimise the number of ground stations not able to communicate.
All systems were implemented and tested. The SCSS executing on the Satellite
was developed and tested on the satellite on-board computer. Embedded implementations
possess strict resource limitations, which were taken into account during the
development process. The SCSS is a multi-threaded system that makes use of thread
cancellation to improve responsiveness. / AFRIKAANSE OPSOMMING: Die Universiteit van Stellenbosch ontwerp tans ’n satelliet kommunikasieloonvrag in
samewerking met die Katolieke Universiteit van Leuven. Die doel van die projek is
om navorsing te doen oor die lewensvatbaarheid van dinamies verstelbare antenna
bundelvorming vir ruimte toepassings, asook om die haalbaarheid van hierdie navorsing
in die praktyk te demonstreer.
Die praktiese toepassing is ’n satellietkommunikasiestelsel vir afstandsmonitering,
wat in ’n Lae-Aarde wentelbaan verkeer. Soos die satelliet in sy wentelbaan beweeg,
sal sensor data na die satelliet toe gestuur, gestoor en weer aangestuur word. Die
stelsel gebruik goedkoop sensorgrondstasies om data te versamel en aan te stuur na
kragtiger grondstasies vir verwerking.
Afstandsmoniteringstelsels kan gebruik word om klimaatsverandering, sowel as
die posisie van skepe en voertuie, te monitor. Deur oa. klimaatsveranderinge te
dokumenteer, kan gevolge en oorsake van globale verhitting gemonitor word.
Die Katholieke Universiteit van Leuven is verantwoordelik vir die ontwerp en
vervaardiging van die satelliet antenna, terwyl die Universiteit van Stellenbosch verantwoordelik
is vir die ontwerp en bou van die kommunikasie loonvrag. ’n Gedeelte
van hierdie ontwikkeling sluit die ontwerp en implementasie van al die protokolle van
die kommunikasieprotokolstapel in. Dit fokus op die toepassingsvlak protokol van die
protokolstapel, wat alle leêrvlak kommunikasie hanteer en die kommunikasiestrategie
implementeer.
Die toepassingsvlaksagteware word die Satellietkommunikasie sagtewarestelsel
(SKSS) genoem. Die SKSS is daarvoor verantwoordelik om alle navrae vanaf grondstasies
te hanteer. Hierdie navrae sluit die oplaai en stoor van data, die aflaai van
data, die aflaai van logs en die oplaai van konfigurasie inligting in. Die ontwerp
is op die standaard kliënt-bediener model gebasseer, met ’n stasiebediener en ’n
stasiehanteerder. Die stasiebediener skeduleer die tye wanneer grondstasies toegelaat
sal word om te kommunikeer en skep stasiehanteerders om alle navrae vanaf die
stasies te hanteer. Gedurende die ontwerp is alle leêrformate gedefinieer om doeltreffende
adminstrasie van die stelsel, asook kommunikasie tussen grondstasies en die
satelliet te ondersteun. Alle geldige boodskappe tussen die satelliet en grondstasies
is ook gedefnieer.
Daar is gevind dat die doeltreffendheid van die stelsel verhoog kan word deur die
grondstasies wat wil kommunikeer te skeduleer, eerder as om alle stasies te pols totdat
een reageer. Om so ’n skedule op te stel, moet die tye wanneer grondstasies binne
bereik van die satelliet gaan wees voorspel word. Hierdie voorspelling is gedoen deur
die posisies van die satelliet en die grondstasies as funksies van tyd te voorspel. ’n
Eenvoudige satelliet posisievoorspeller is ontwikkel om toetsing en integrasie met die SKSS te vergemaklik. ’n Skeduleringsalgoritme is toe ontwikkel om die hoeveelheid
grondstasies wat nie toegelaat word om te kommunikeer nie, te minimeer.
Alle stelsels is geimplementeer en getoets. Die SKSS, wat op die satelliet loop,
is ontwikkel en getoets op die satelliet se aanboord rekenaar. Die feit dat ingebedde
stelsels oor baie min hulpbronne beskik, is in aanmerking geneem gedurende die
ontwikkeling en implementasie van die SKSS. Angesien die SKSS ’n multidraadverwerkingsstelsel
is, word daar van draadkansellasie gebruik gemaak om die stelsel se
reaksietyd te verbeter.
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Convergence of the naval information infrastructureKnoll, James A. 06 1900 (has links)
Approved for public release, distribution is unlimited / Converging voice and data networks has the potential to save money and is the main reason Voice over Internet Protocol (VoIP) is quickly becoming mainstream in corporate America. The potential VoIP offers to more efficiently utilize the limited connectivity available to ships at sea makes it an attractive option for the Navy. This thesis investigates the usefulness of VoIP for the communications needs of a unit level ship. This investigation begins with a review of what VoIP is and then examines the ship to shore connectivity for a typical unit level ship. An OMNeT++ model was developed and used to examine the issues that affect implementing VoIP over this type of link and the results are presented. / Lieutenant Commander, United States Navy
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High-Sensitivity Phased Arrays for Radio Astronomy and Satellite CommunicationsDiao, Junming 01 March 2017 (has links)
Radio astronomy is used to study stars, galaxies, black holes and gas clouds radiation at radio frequencies. Detecting extremely weak signals from deep space radio sources requires high sensitive feed system associated with large dish antennas. The key figure of merit is survey speed, or the time required to map a region of the sky to a given source flux density. Survey speed is proportional to the frequency bandwidth, the field of view or observable region of the sky, and the squared sensitivity, where sensitivity is related to reflector aperture efficiency and system noise temperature. Compared to the traditional single feed, phased array feeds with significantly expanded field of view are considered as the next generation feed for radio telescope. This dissertation outlines the design, analysis and measurement of high sensitivity L-band and mm-wave phased array feeds for the 100-meter Green Bank Telescope. Theoretical works for radio astronomy includes design guideline for high sensitivity phased array feed, fundamental frequency bandwidth limit, array antenna loss influenced by mutual coupling and beamformer coefficients and possibility of superdirectivity for radio telescopes and other antennas. These study are helpful to understand and guide the design of a phased array feed system. In the absence of dish antennas, sparse phased arrays with aperiodic structure have been developed for satellite communications. A compromise between the peak side lobe level, array element density, directivity and design complexity is studied. We have found that the array peak side lobe level can be reduced by enhancing the array element direction at the main lobe direction, increasing the array element density and enlarging the array size. A Poynting streamline approach develops to understand the properties of a receiving antenna and the mutual coupling effects between array elements. This method has been successfully used to generate effective area shape for many types of antennas and guide the design of a superdirective antenna. Motivated by this method, a superdirective antenna is experimental demonstrated.
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Tracking collar and infrastructure for leopard researchWarnich, Dirk J. 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This project targeted the development of a new tracking collar, trap telemetry system
and supporting infrastructure, to aid researchers from the Cape Leopard Trust. Previously
used collar products had all proven insu cient in some capacity and remote monitoring of
trap sites was also required. Tracking collars are used to identify the movement patterns
of the leopards and through the resulting research, assist in protecting this threatened
species. In the development of the tracking collar and trap telemetry system, a high level
system design was rst formulated, identifying major components that would be required.
Alternative methods for implementation were then considered and the most optimal chosen.
Two di erent modes of communication with the collar were envisioned and designed for.
These would be used to transmit logged coordinates obtained from a GPS receiver back to
researchers. A VHF terrestrial radio link was investigated, but an Iridium Satellite based
solution was ultimately selected. An Iridium Satellite communications system was also used
for transfer of trap state data. Ultimately, a working trap telemetry system was delivered
for use by researchers. The tracking collar system had progressed to a working prototype,
requiring miniaturisation and packaging before deployment. A possible packaging solution
was also identi ed. The trap telemetry system, although displaying certain de ciencies,
provided a capability previously unavailable to researchers. With further development, there
is potential for the tracking collar to provide accurate satellite tracking and communications
in a mass and price combination not previously available. / AFRIKAANSE OPSOMMING: Hierdie projek het as doel die ontwikkeling van 'n nuwe opsporingshalsband, 'n lokval
telemetriese stelsel en die nodige ondersteunende infrastruktuur daarvoor. As hulpmiddels
vir navorsers van Cape Leopard Trust. Geen van die halsband produkte wat tot nou toe
gebruik is, het voldoen aan al die nodige behoeftes nie, en dit was ook nodig om die
lokvalterreine van 'n afstand te kan monitor. Die opsporingshalsbande word gebruik om
die bewegingspatrone van luiperds vas te stel en die navorsing wat daarop volg, help dat
'n bedreigde spesie bewaar word. Die ontwikkeling van die opsporingshalsband en lokval
telemetriese stelsel het begin met die formulering van 'n ho evlak stelselontwerp waarin
die hoofkomponente wat benodig sou wees ge denti seer is. Alternatiewe metodes van
bewerkstelling is daarna oorweeg en die optimale hiervan is gekies. Twee verskillende
metodes van kommunikasie met die halsband is voorgestel en ontwerp. Hierdie sou gebruik
word om die vasgelegte koordinate wat van 'n GPS ontvanger verkry is, na navorsers terug
te versend. 'n Terrestriale radioverbinding is ondersoek, maar 'n Iridium Satelliet-baseerde
oplossing is uiteindelik verkies. 'n Iridium Satelliet kommunikasie stelsel is ook gebruik
vir die oordrag van data aangaande die lokvaltoestand. Uitendelik is 'n werkende lokval
telemetriese stelsel gelewer vir dir gebruik van navorsers. Die opsporingshalsband stelsel
was nou 'n werkende prototipe, wat slegs verklein en toepaslik verpak moes word voor dit
in gebruik geneem kon word. 'n Moontlike oplossing tot die verpakkingsprobleem is ook
identi seer. Die lokval telemetriese stelsel, hoewel dit steeds tekorte toon, voorsien die
navorsers van voorheen onbekombare inligting. Met verder ontwikkeling is daar potensiaal
vir die opsporingshalsband om akkurate satellietopsporing en kommunikasie te voorsien in
'n kombinasie van laer massa, sowel as prys, soos nog nooit voorheen beskikbaar nie.
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Equalization of Non-linear Satellite Communication Channels using Echo State NetworksBauduin, Marc 28 October 2016 (has links)
Satellite communication system designers are continuously struggling to improve the channel capacity. A critical challenge results from the limited power available aboard the satellite.Because of this constraint, the onboard power amplifier must work with a small power supply which limits its maximum output power. To ensure a sufficient Signal-to-Noise power Ratio (SNR) on the receiver side, the power amplifier must work close to its saturation point. This is power efficient but unfortunately adds non-linear distortions to the communication channel. The latters are very penalizing for high order modulations.In the literature, several equalization algorithms have been proposed to cope with the resulting non-linear communication channel. The most popular solution consists in using baseband Volterra series in order to build non-linear equalization filters. On the other hand, the Recurrent Neural Networks (RNNs), which come from the artificial neural network field, are also interesting candidates to generate such non-linear filters. But they are difficult to implement in practice due to the high complexity of their training. To simplify this task, the Echo State Network (ESN) paradigm has been proposed. It has the advantage of offering performances similar to classical RNNs but with a reduced complexity.The purpose of this work is, first, to compare this solution to the state-of-the-art baseband Volterra filters. We show that the classical ESN is able to reach the same performances, evaluated in terms of Bit Error Rate (BER), and has similar complexity. Secondly, we propose a new design for the ESN which achieves a strong reduction in complexity while conserving a similar BER.To compensate for the channel, the literature proposes to adapt the coefficients of these equalizers with the help of a training sequence in order to recover the transmitted constellation points. We show that, in such a case, the usual symbol detection criterion, based on Euclidean distances, is no longer optimal. For this reason, we first propose a new detection criterion which meets the Maximum Likelihood (ML) criterion. Secondly, we propose a modification of the equalizers training reference points in order to improve their performances and make the detection based on Euclidean distances optimal again. This last solution can offer a significant reduction of the BER without increasing the equalization and detection complexity. Only the new training reference points must be evaluated.In this work, we also explore the field of analog equalizers as different papers showed that the ESN is an interesting candidate for this purpose. It is a promising approach to reduce the equalizer complexity as the digital implementation is very challenging and power-hungry, in particular for high bandwidth communications. We numerically demonstrate that a dedicated analog optoelectronic implementation of the ESN can reach the state-of-the-art performance of digital equalizers. In addition, we show that it can reduce the required resolution of the Analog-to-Digital Converters (ADCs).Finally, a hardware demonstration of the digital solutions is proposed. For this purpose, we build a physical layer test bench which depicts a non-linear communication between two radios. We show that if we drive the transmitter power amplifier close to its saturation point, we can improve the communication range if the non-linear distortions are compensated for at the receiver. The transmitter and the receiver are implemented with Software Defined Radios (SDRs). / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
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Rapid Response Command and Control (R2C2): a systems engineering analysis of scaleable communications for Regional Combatant CommandersSullivan, Lisa, Cannon, Lennard, Reyes, Ronel, Bae, Kitan, Colgary, James, Minerowicz, Nick, Leong, Chris, Lim, Harry, Lim, Hang Sheng, Ng, Chin Chin, Neo, Tiong Tien, Tan, Guan Chye, Ng, Yu Loon, Wong, Eric, Wong, Heng Yue 06 1900 (has links)
Includes supplemental material. / Disaster relief operations, such as the 2005 Tsunami and Hurricane Katrina, and wartime operations, such as
Operation Enduring Freedom and Operation Iraqi Freedom, have identified the need for a standardized command and control
system interoperable among Joint, Coalition, and Interagency entities. The Systems Engineering Analysis Cohort 9 (SEA-9)
Rapid Response Command and Control (R2C2) integrated project team completed a systems engineering (SE) process to
address the military’s command and control capability gap. During the process, the R2C2 team conducted mission analysis,
generated requirements, developed and modeled architectures, and analyzed and compared current operational systems versus
the team’s R2C2 system. The R2C2 system provided a reachback capability to the Regional Combatant Commander’s (RCC)
headquarters, a local communications network for situational assessments, and Internet access for civilian counterparts
participating in Humanitarian Assistance/Disaster Relief operations. Because the team designed the R2C2 system to be
modular, analysis concluded that the R2C2 system was the preferred method to provide the RCC with the required flexibility
and scalability to deliver a rapidly deployable command and control capability to perform the range of military operations.
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[en] EFFICIENT USE OF THE GEOESTATIONARY SATELLITE ORBIT: ORBITAL POSITION OPTIMIZATION / [pt] USO EFICIENTE DA ÓRBITA DE SATÉLITES GEOESTACIONÁRIOS: OTIMIZAÇÃO DAS POSIÇÕES ORBITAISMARCELLE SANTIAGO DO NASCIMENTO 22 July 2005 (has links)
[pt] Este trabalho está relacionado ao problema do uso eficiente da órbita de satélite geoestacionário. A utilização eficiente da órbita é obtida através de um algoritmo de otimização que permite escolher as
posições orbitais para os diversos sistemas de modo a reduzir ao máximo o percentual do arco orbital
utilizado. Sendo assim, desenvolvido um modelo matemático que considerou além de aspectos de interferência, detalhes da geometria envolvida no problema (posições orbitais dos satélites, posições das
estações terrenas, apontamento de antenas, etc.). Este modelo foi utilizado na definição de um problema de otimização com restrição cuja função objetivo se baseia na parcela do arco orbital utilizado. Neste problema de otimização com restrição foram consideradas restrições de níveis máximos de interferência
(de entrada única e agregada) além de restrições de arcos orbitais, impostas por aspecto de propagação. O algoritmo de otimização utilizado requer o cálculo do Vetor Gradiente e da Matriz Hessiana. Para
evitar erros de origem numéricos essas quantidades foram calculadas utilizando expressões
analíticas desenvolvidas neste trabalho. O método matemático foi aplicado a situações específicas conduzindo a resultados que mostraram um uso eficiente da órbita de satélites geoestacionários através
de soluções onde a parcela utilizada do arco é minimizada. / [en] This work is related to the efficient use of the geostationary satellite orbit. It presents and describes an optimization model which chooses the best orbital position for each satellite so that the length used
orbital arc is minimized. A mathematical model considering aspects such as interference, geometry
details (orbital position of the systems, earth station position, boresight of the antenna, etc) is proposed. This model was used in the definition of a constrained optimization problem in which the cost
function is the length of the used orbital arc. Constrained imposed by propagation aspects (minimum elevation angle) and by the maximum allowable interference levels (aggregate and single-entry) are considered. The optimization algorithm requires the evaluation of the Gradient vector and the Hessian matrix. To avoid numeric problems, analytic expressions of these quantities were derived. Results of the application of this model to specific situations involving real data were also described and conducted to solutions where the length of the orbit used was minimized
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[en] A SEMI-EMPIRIC CONSISTENT MODEL FOR RAIN ATTENUATION PREDICTION IN TERRESTRIAL AND SATELLITE RADIO LINKS / [pt] PREVISÃO DA ATENUAÇÃO POR CHUVAS ATRAVÉS DE UMA MODELAGEM SEMI-EMPÍRICA CONSISTENTE PARA ENLACES RÁDIO TERRESTRE E VIA SATÉLITERODRIGO MARTINS DE SOUZA 13 February 2007 (has links)
[pt] Com a crescente utilização de sistemas de acesso sem fio
ponto-multiponto
em banda larga, operando em freqüências cada vez mais
elevadas, cresce também
a necessidade do desenvolvimento de novos modelos, mais
precisos e
consistentes, para a previsão da atenuação por chuvas,
principal efeito da
propagação em freqüências superiores a 10 GHz. Este
trabalho apresenta uma
modelagem semi-empírica para a previsão do comportamento
estatístico da
atenuação por chuvas em enlaces rádio terrestres ponto-a-
ponto e via satélite. Os
modelos foram desenvolvidos com base em resultados de
medições conjuntas de
taxa de precipitação e atenuação por chuvas em diversas
regiões do Brasil,
realizadas no período de desenvolvimento deste trabalho,
além de medidas de
várias partes do mundo, disponíveis no banco de dados de
propagação da União
Internacional de Telecomunicações (UIT-R). Os modelos
desenvolvidos
permitem obter a distribuição cumulativa de probabilidades
da atenuação por
chuvas a partir da distribuição da taxa de precipitação
medida ou estimada na
região do enlace. Embora existam diversos modelos
propostos na literatura para
previsão da atenuação em enlaces terrestres ou em enlaces
via satélite, duas
características importantes não são encontradas,
conjuntamente, na maioria deles:
utilizar, como base para a previsão, a distribuição da
taxa de precipitação em toda
a faixa de percentagens de tempo de interesse, e não
apenas em um ou dois
pontos; e manter consistência entre os modelos para os
casos terrestre e via
satélite. Além não de atender a estes requisitos, os
modelos propostos apresentam
erros de previsão menores ou equivalentes aos dos
principais modelos da
literatura, quando testados contra os resultados
disponíveis de medidas em enlaces
reais. / [en] The development of new technologies for broadband wireless
access, using
increasingly higher frequencies, points to the necessity
of more accurate methods
for rain attenuation, that represents the most serious
impairment for radio systems
operating in frequencies above 10 GHz. This work presents
semi-empirical
models for the prediction of rain attenuation in
terrestrial and satellite links. The
models were developed using data obtained in concurrent
measurements of rain
attenuation and point rainfall rate in different regions
of Brazil. Some of these
measurements were performed as part of this work and some
were already
available from previous measurements campaigns. Data
available in the UIT-R
data banks of propagation measurements were also used, in
order to develop
global methods. The models that have been developed allow
the prediction of the
cumulative probability distribution of rain attenuation
from the cumulative
distribution of point rainfall rate in the region of the
link. Although several
methods with these purpose can be found in the technical
literature, the ones
developed in this work present some important features
that are not found, as a
whole, in any of those models: they use the full rainfall
rate distribution over the
entire range of time percentages of interest; the
terrestrial and satellite models are
consistent, that is, the elements used in the terrestrial
prediction model are kept in
the satellite prediction model that involves a mor complex
geometry. Besides that,
the models proposed show an excelent performance in terms
of prediction error,
when compared with measured data.
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