ISSN:0737-2884    

DOI:10.1002/sat.4600050202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600050203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600050204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper discusses on‐board processing systems and associated benefits including connectivity, increased capacity, lower costs and system improvements; there are complex trade‐offs in design approaches. Several architectures are described which use a microwave switch matrix, a baseband switch matrix or baseband processor. Regeneration (an advanced form of on‐board processing) consists of demodulation followed by remodulation and provides access to baseband signals. The link advantages of this method are clearly presented for 120Mb/s TDMA and for IBS at 1/544 Mb/s. Additionally, there are discussions of five architectures using multi‐carriers per transponder, and their advantages and disadvantages. Some considerations of using on‐board decoding and baseband processing functions are also briefly

ISSN:0737-2884    

DOI:10.1002/sat.4600050205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe continuing improvement of RF components, particularly in the field of spot‐beam antennas, combined with the steady progress in digital technology, leads us to consider the advantages of a satellite system able to provide full connectivity to ground stations operating at different data rates. For low data rates, two different access methods: continuous TDM and Multi‐carrier TDMA, are compared for earth‐stations operating at 2Mb/s. The two methods are compared from the point of view of efficiency and adaptability in a non‐uniform load environment.Some control criteria are proposed for the Multi‐carrier system.Both methods are particularly suited for sm

ISSN:0737-2884    

DOI:10.1002/sat.4600050206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper is composed of two parts.The first part addresses some topics associated to the implementation of FDMA/TDM systems for ‘business’ services applications, operating atKaband.A modular regenerative and processing satellite repeater, each module capable of handling up to 16 up‐link carriers in the 2 Mb/s range is considered. Available coding techniques were reviewed; concatenated codes seem highly interesting because of the high coding gains achievable with two simpler co‐decoding processes in series, and also because they lead to an implementation wherein the internal coder is installed on board the satellite, while the external one is installed in the user terminals.The problem of keeping stable the up‐link carriers in the satellite demodulators is discussed and a compensation method is proposed.Finally, simulation results of co‐decoding and carrier extraction performance are illustrated.The second part concerns the implementation of a multifrequency TDMA system. This is a hybrid system whereby the access for up‐links uses time and frequency slots in a time‐frequency map. The adoption of a clock synchronous network allows a frame for which no preamble and guard time are inserted between the burst.The error contributions and the performance of the clock synchronous network are assessed. A solution to the problem of fast phase/frequency estimation is proposed.For a clock synchronous network fast algorithms suitable for frequency demultiplexing and detecting of the FDM signal could be adopted; a modular solution to the implementation of the demultiplexer and detector is proposed based on the use of an optimized matched filter; a multistage scheme minimizes the number of

ISSN:0737-2884    

DOI:10.1002/sat.4600050207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe paper considers the application of satellite on‐board processing (OBP) technology for land mobile applications for possible introduction in the late 1990s. Initially a system outline is presented followed by a discussion considering the merits of OBP over conventional transparent payloads. The paper then presents an overview of the work being carried out as part of an ESA study. Some details on the critical parts of the system are also include

ISSN:0737-2884    

DOI:10.1002/sat.4600050208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe derivation of a system concept for the digital multi‐service repeater starts from evaluating the mission profile and the antenna concept elaborated so far. Furthermore, the repeater concept is shaped by Ka‐band propagation conditions, the kind of integration of a down‐link TV‐distribution service into the prevailing multi‐beam communications mode and readily available digital technologies. It is intended to embark on a completely regenerative approach using a unified switching concept for all services accompanied by a large amount of rearrangement functions in the foreground. An attempt is made to define those network control functions and procedures to be located on‐board exploiting the fact that the repeater already acts as a central switching node. The discussion of on‐board digital technologies concentrates upon a multicarrier demodulator concept and a candidate solution for the baseband switch. One general boundary condition is pronounced due to uncertainties about the actual traffic scenario in the future: all repeater resources must be accessible for the most important of the services considered, i.e. the provision of satellite busi

ISSN:0737-2884    

DOI:10.1002/sat.4600050209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper describes new on‐board equipment built around a microprocessor and controlled by earth through a specialized link. It drives in real‐time a 4 × 4 microwave switch matrix (MSM) for operation in satellite‐switched time division multiple access (SS/TDMA). The system is designed to evaluate SS/TDMA performances when (i) frame and multiframe durations are changed, (ii) the switch states sequence which controls the MSM is updated in real‐time. Another specific feature of this versatile equipment is the possibility to modify upon earth request the program run by the microprocessor to be able to carry out further exp

ISSN:0737-2884    

DOI:10.1002/sat.4600050210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis paper presents technologies which are key candidates for advanced on‐board processing for future communication satellites. Satellite switching centres for microwave and baseband signals, on‐board coherent modems for 120Mb/s burst‐mode TDMA systems and their technologies are discussed. A brief description of on‐board demultiplexing and demodulation of low bit rate carriers is offered and study results on investigation of on‐board unique word detectors and large buffers are

ISSN:0737-2884    

DOI:10.1002/sat.4600050211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY