bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of pose repeatabilty of stewart platform
Authors: Masory Oren , Jiahua Yan 
Published: July 2007

AbstractManufacturing tolerances, installation errors, link offsets, and controller errors effect the positioning repeatability of serial and parallel manipulators. A variety of measurement methods have been proposed and used to measure the repeatability of serial manipulators. However, these methods might not be suitable for parallel manipulators due to limited instrumentation accessibility and the large structure involved. This article describes two measurement procedures by which the position of a target point in three‐dimensional space can be determined using a single theodolite that is used to collect two sets of measurements taken from two arbitrary locations. The required hardware needed for the implementation of this method is two standard measuring tapes installed vertically at two arbitrary locations, or one horizontal bar. If the target points are located on the end effector of a manipulator, its repeatability can be measured. The procedure that uses two vertical tapes was used to measure the repeatability of a Stewart Platform and experimental results are provided. © 2995 John Wiley & Sons, Inc.
State and dynamic behavior of a high stiffness stewart platform‐based force/torque sensor
Authors: Ferraresi C. , Pastorelli S. , Zhmud' M. Sorli N. 
Published: July 2007

AbstractThe performance of a Stewart platform‐based force/torque sensor is analyzed. The influence of sensor geometry is assessed with particular reference to the characteristic orientation angles of the arms connecting the platforms, which consist of single‐axis bidirectional force transducers. Static and dynamic performance is analyzed and compared with experimental tests, © 7993 John Wiley & Sons, Inc.
Companded single sideband (CSSB) AM/FDMA Performance
Authors: Campanella S. J. 
Published: July 2007

AbstractThe continuing need for increased traffic capacity for telephony over satellite links combined with the availability of low cost and accurate LSI compander chips has caused renewed interest in SSB satellite transmission using companders to reduce the impairments caused by thermal noise, interference and intermodulation encountered on the transmission link. This type of transmission is designated as CSSB/AM and may be operated in a multicarrier per transponder (FDMA) manner. The capacity achieved is a function of the average power during the occurrence of speech and because this value has decreased in modern telephone systems, the advantages to be gained from CSSB/AM are increased.This paper presents the development of expressions for channel capacity of CSSB/AM links as a function of carrier‐to‐noise ratio and speech power level while active. These are used to estimate the capacity achievable in an INTELSAT IV type transponder.
Introduction of companded FDM/FM operation into the intelsat system
Authors: Pontano B. A. , Szarvas G. G. 
Published: July 2007

AbstractINTELSAT has been studying the application of compandors in its existing FDM/FM system for a number of years. Laboratory and field tests have demonstrated the technical suitability of these devices for use on INTELSAT satellite links. Companded FDM/FM (CFDM) has recently been approved for use by INTELSAT signatories. The first CFDM service was inaugurated in April 1983 between the Etam Standard A earth station (U.S.A.) and the Grand Cayman Standard B earth, station (Cayman Islands).
Japanese commercial tdma system
Authors: Suzuki R. , Hayashizaki H. , Mitani T. , Saga R. 
Published: July 2007

AbstractThis paper reviews two TDMA systems which have been developed at NTT (Nippon Telegraph and Telephone Public Corporation) for domestic use in Japan.The first system uses K‐Bands (30/20 GHz) and is called the TDMA‐65M system. This system constructs a variable channel capacity network between 8 major cities (regional centres).The second system uses C‐Bands (6/4 GHz) and is called the TDMA‐100M system. This system provides remote island communication links for simultaneous transmission of voice and colour television signals.These two TDMA systems were put into commercial operation in summer 1983 by using, respectively, the Communication Satellite‐2s, CS‐2a which was launched in February 1983 and CS‐2b which was launched in August 1983.
Design considerations for a larger inmarsat standard ship earth station
Authors: Nouri M. , Braine M. R. 
Published: July 2007

AbstractA new standard of INMARSAT ship earth station for multi‐channel operation could find particular application on large passenger ships and off‐shore oil/gas platforms. This paper provides estimates of platform and ship motions and discusses general design requirements, notably of the antenna system. The discussion includes consideration of possible modulation and multiple access techniques. Single channel per carrier (SCPC) operation is advocated which permits easy integration with the present service to single channel INMARSAT Standard‐A ship earth stations. Major parameter/relative cost trade‐off curves needed in an overall ship earth station design optimization are presented.
Satellite broadcasting: System concepts and the television transmission standards for europe
Authors: Phillips G. J. , Shelswell P. 
Published: July 2007

AbstractWithin Western Europe several countries have indicated their intention to start DBS services in the 12 GHz band in 1985/6 or soon after. Against this background the European Broadcasting Union has recommended a common transmission standard known as C‐MAC/packet. An outline is given of the system, with a discussion of the requirements for a broadcasting satellite and receivers for individual reception.
Satellites for communications and broadcasting: The evolving european market
Authors: Morris R. 
Published: July 2007

AbstractThe paper traces the development of the market for communications and direct broadcasting satellites in Europe, since the original specification of the European Communications Satellite (ECS) in 1977. It reviews the experiments undertaken on the Orbital Test Satellite (OTS) and the way in which demonstrations with this satellite have influenced the way in which ECS is being developed.It continues by considering the impact of television on the market, first cable television and its distribution requirements, then direct broadcasting by satellite, where the introduction of homes into the customer configuration will bring with it programme content as a salient feature in market development.Finally it speculates on the possibilities for the future, both in terms of the effect of new and higher frequencies on satellite communications systems, and the possible effects that interaction from small earth‐stations could have on satellite design.
Performance of regenerative/conventional satellite systems
Authors: Maral G. , Bousquet M. 
Published: July 2007

AbstractA great many papers have been devoted in the last few years to the advantages of regenerative communications satellite systems when compared to conventional ones. This paper attempts to summarize the most significant results which are scattered in the literature, and to provide a tutorial overview of this comparison. Linear and non‐linear satellite channel performances, with and without interference, are discussed. The major impacts on system design provided by on‐board regeneration are also presented.
Earth‐station size Vs. Error‐correction coding in the design of ku‐band satellite communications systems
Authors: Mangulis V. 
Published: July 2007

AbstractA Ku‐band satellite transponder capacity is evaluated for a PCM/QPSK/FDMA system in which many carriers are transmitted in an SCPC mode. The capacity depends on earth‐station sizes, error‐correction coding, required signal‐to‐noise ratio and required availability in rain; for simplicity all of these parameters are assumed to be the same for all carriers in the transponder. A method of accounting for the effects of rain is developed; it is assumed that the earth‐stations do not adjust their output power when it rains. Trade‐offs between earth‐station sizes and error‐correction code rates are examined.
The intelsat spade system—ten years of demand assigned operation
Authors: Lynn S. 
Published: July 2007

AbstractIn this paper, the INTELSAT SPADE system is re‐examined after 10 years of operation in the Atlantic Ocean Region. A functional description of the system is provided together with its technical evolution from the early years of development to the current maturity. Network monitoring and control, together with a summary of the SPADE System's activity from its traffic statistics and billing information are also discussed. Finally, it is shown that SPADE has fully met its original purpose and, based on the continuing high usuage of the SPADE system and the availability of a new generation SPADE terminal, SPADE will continue to be an important service for many years to come.
Design architecture for a high performance intelsat tdma/dsi terminal
Authors: Gaske Paul , Thompson Steve 
Published: July 2007

AbstractIn recent years, communication equipment performance and reliability have become dominated by software factors. The architecture of the software, as well as the hardware, has a substantial impact on the software performance and, thus, the equipment performance.This paper focuses on the software and hardware architectures of a time division multiple access (TDMA) terminal and a digital speech interpolation (DSI) unit, which have been specifically designed to optimize software performance. This equipment is designed to operate in the INTELSAT and EUTELSAT TDMA networks.
120 Mb/s tdma traffic terminal for use in the intelsat system
Authors: Nakanishi M. , Itoh H. 
Published: July 2007

AbstractThis paper presents the design concept, the design features, and the configuration of the 120 Mb/s TDMA traffic terminal for use in the INTELSAT or EUTELSAT Systems. The description covers the redundancy concept, the control and supervisory system, the BTP processing method, internal interfaces between subsystems, expandability and capacity of the system, and the overall operation and maintenance concepts.The detailed design of each subsystem is discussed, from the IF interface with the earth‐station transmit and receive equipment down to the terrestrial interface equipment. Special emphasis is given to design features associated with redundancy of the terminal equipment yielding the required operation availability, and on the scheme for supervisory data handling across the international trunk circuit through the TDMA network. As a part of the discussion, the equipment mechanical sizes and anticipated heat dissipation are presented.
16 Kb/s high quality voice encoding for satellite communication networks
Authors: Yatsuzuka Yohtaro , Yamazaki Tomohiro , Hzuka Shigeru 
Published: July 2007

AbstractThis paper describes applications of adaptive predictive coding (APC) with maximum likelihood quantization (MLQ) which can cover a wide range of coding rates from 4.8 to 16 kb/s for low C/N satellite communication systems, such as maritime, aeronautical mobile and thin‐route satellite communication systems, and also for speech and data integration, including digital circuit multiplication equipment (DCME) in business communication systems, such as INTELSAT business services (IBS). A 16 kb/s APC–MLQ hardware codec has been implemented by NEC–7720 DSP chips and the performance has been confirmed in subjective quality of speech through conversational tests. The objective performance has also been evaluated for non‐voice signals, such as single and multi‐frequency tones, and 1200 and 2400 b/s voiceband data signals. The APC‐MLQ codec can transmit the voice‐band data at 1200 b/s over two asynchronous tandem links and at 2400 b/s over one link. It was noted that the APC‐MLQ codec is superior in speech performance at 16 kb/s to a narrow‐band companded FM and meets requirements for low C/N satellite communication systems. For voice and data integration into 16 kb/s for 64 kb/s links, we propose a multi‐media multiplexing for low C/N digital satellite communication systems and also a small‐scale circuit multiplication system for business use. In these systems, a variable rate coding of APC‐MLQ from 4.8 to 16 kb/s can be effectively introduced for voice and data integration.
Universal digital TV codec—unicodec
Authors: Kinuhata K. , Nuspl P. , Kwan A. , Yamamoto H. , Murakami H. , Matsumoto S. 
Published: July 2007

AbstractThe UNICODEC, developed under the INTELSAT R & D Program, is a TV codec which can transmit and receive any standard signal of NTSC, PAL, or SECAM, by using 15 Mb/s or 30 Mb/s transmission rates (switchable) with two high quality sound channels and one voice circuit. These rates include rate 239/255 BCH FEC for video information. The codec uses the 4:2:2 digital interface for component coding based on CCIR Recommendation 601.The UNICODEC can provide the flexibility to deal with the composite coding now needed in mixed analogue/digital networks, but can also handle either composite NTSC, PAL, SECAM or MAC (multiplexed analogue components), or digital component signals (Y, R‐Y, B‐Y) in the future.The key technique used here is called MAP (median adaptive prediction) coding, which is one of the adaptive DPCM methods for accurate and simple control in high quality TV transmission; one prediction out of three (interframe, intrafield or interfield) is transmitted without the need for many control bits. There is also a refresh mode for burst error or synchronization recovery. The UNICODEC is expected to provide double capacity with higher quality pictures compared to conventional analogue transmission (FM in 18 MHz). Alternatively, smaller size antennas may be used.This paper describes the objectives of the development of the UNICODEC, its main features and results of field tests.
Selection of gold and kasami code sets for spread spectrum CDMA systems of limited number of users
Authors: El‐khamy Said E. , Balamesh Ahmed S. 
Published: July 2007

AbstractSpread spectrum code‐division multiple‐access (CDMA) systems are currently considered as very attractive alternatives to the more familiar FDMA and TDMA systems, especially in the presence of multipath fading and external interference. The problem of code selection in a CDMA system with a finite number of users is addressed in this paper. A simple and efficient method for the selection of finite code sets with relatively high processing gain from Gold and Kasami code families of relatively large sizes is described in detail. Selected code sets of period 63 are presented along with their overall average performance parameters for different number of users.
In‐orbit testing of digital regenerative satellite: The italsat planned test procedures
Authors: Saggese E. , Speziale V. 
Published: July 2007

AbstractITALSAT is the Italian pre‐operational satellite, funded by the National Council of Research, to be launched in late 1989. It will carry three payloads, the most innovative and challenging being a multi‐spot regenerative package providing the interconnection among six spots at 147Mb/s with SS TDMA access scheme.In‐orbit tests (IOT) will be performed on this payload in order to verify, to the maximum possible extent, the radioelectric characteristics and the behaviour of the modems and baseband switching equipment. The importance of these measurements is two‐fold: incentive payment schemes can be applied for better‐than‐specified characteristics and the information obtained by the tests will permit gathering the information needed for the establishment to a domestic operational system.The non‐transparent structure limits applicability of many classical RF measurements: the opportunity of adding some on‐board hardware to permit the testing of the most important parameters has been suggested. The design objectives have been to minimize the on‐board additional hardware complexity and to concentrate the test equipments on ground, in the IOT earth‐station. This paper illustrates the planned additional satellite hardware and the test procedures to be implemented for the in orbit testing.
Performance of fully variable demand assignment SS/TDMA satellite systems
Authors: Maral Gérard , Bousquet Michel 
Published: July 2007

AbstractFully variable demand assignment in a SS/TDMA satellite system requires frequent burst time plan changes with reconfiguration of the on‐board switch matrix state sequence. The burst managment presented in this paper assumes that bursts are not reconfigurated into new bursts during such burst time plan changes but merely shifted in time. The performance of this burst management procedure as obtained from simulations over three different networks is reported in terms of throughput gains, required signalling capacity and time required to change burst time plan.
The TDMA burst‐mode link analyser with least‐squares algorithm
Authors: Liu Yi‐Song , Feng Shi‐Qin 
Published: July 2007

AbstractThe burst‐mode link analyser with the decompositional least‐squares algorithm (BMLA/LS) is an attractive and novel computational approach for impulse response measurement and equalization of a QPSK/TDMA satellite communication channel. Analysis and simulation confirms it to be superior to the current BMLA/radar approach. This paper presents a brief and systematic introduction to the methodology of the subject, and to software simulation, system design and hardware implementation.
A comparison of the implementation and annual operating costs of IDR and TDMA in the intelsat system
Authors: Colby R. J. , Kwan A. K. 
Published: July 2007

AbstractThe outcome of a preliminary systems cost study which compares the cost of operating INTELSAT intermediate data rate (IDR) and time division multiple access (TDMA) stations under various conditions is reported. The differences in the annual cost of operating the two candidate methods over the range of 1 to 1000 terrestrial channels are derived under the conditions of no CME, DSI only and the use of DCME. For DCME the effect of one, two, three and four destinations per DCME is considered. The results show that while the initial cost of the TDMA equipment is higher than with IDR, the annual cost of operating the systems is dominated by the space segment costs. For this reason the greater bandwidth efficiency, inherent multidestinational capability and ease of capacity expansion of the TDMA system give it a lower annual operating cost, even at fairly moderate earthstation capacities (e.g. for DCME with two destinations TDMA becomes cheaper than IDR for capacities in excess of about 300 channels). There are attributes of both systems which will also influence the network planners' decision. The IDR system is modular in that costs associated with implementation are incurred more gradually than with the TDMA system. Furthermore, IDR is to a great extent an extrapolation of the current FDM/FM/FDMA practice. However, since the equipment costs are small compared to the space segment charges, it may prove advantageous to adopt the lowercost system as soon as possible. In addition, the TDMA system offers significant long‐term advantages of low‐cost expansion and the ability to reconfigure the system with minimal or no loss of traffic.
Principles and design of bidirectional optical isl using GaAlAs laser at λ = O·85 μm and direct detection PPM
Authors: Zhu Zhini 
Published: July 2007

AbstractThis paper gives a general introduction to bidirectional optical intersatellite links. The design, principles and link budget are presented, and the four subsystems—transmitter, receiver, optical channel and acquisition/tracking system—are described. GaAlAs semiconductor laser and a silicon avalanche photodiode are used as the optical transmitter and receiver. Pulse polarization position modulation is used to obtain a higher sensitivity. The acquisition/tracking signal is extracted from the top‐modulation data stream. The effect of background noise is analysed, and direct detection and heterodyne detection are compared.
Functional specifications and evaluation of commercially available laser diodes for optical space links
Authors: Roux Michel , Chauve Denis , Keil‐Simon Geneviève 
Published: July 2007

AbstractCommercially available GaAlAs laser diodes have been tested to predict their behaviour in intersatellite communications. Three types of device with various structures have been investigated: Sharp lasers, Hitachi lasers (single longitudinal mode emission in c.w. operation) and Ortel lasers (multi‐longitudinal modes). Two modulation schemes were applied to devices (NRZ and 4‐PPM), corresponding to the two possible modulation formats selected for ISL experiments. Each laser had an average power output of 30 mW, whatever the modulation mode. The output signal, emission spectrum and beam divergence were measured. A reduction in peak power was found with some devices. Multimode spectra were detected under 4‐PPM modulation.
Multi‐carrier demodulators for on‐board processing satellites
Authors: Yim W. H. , Kwan C. C. D. , Coakley F. P. , Evans B. G. 
Published: July 2007

AbstractA study of the digital transmultiplexor element of an on‐board multi‐carrier demodulator (MCD) results in design data for various architectures (FFT, tree etc.) which can be applied to a wide range of applications. A detailed design based on the latter for a 4 × 16 kb/s MCD for the U.K. T‐SAT mobile OBP payload is presented. Implementation of the MCD using TMS320C25 signal processor technology has been performed and early test results are presented.
A modular multistage approach to digital fdm demultiplexing for mobile SCPC satellite communications
Authors: Göckler Heinz 
Published: July 2007

AbstractA hierarchical multistage method (HMM) for digital demultiplexing of an FDM signal composed of L adjacent SCPC signals is described; L is preferably a power of two, here L=32. This HMM approach to FDM demultiplexing applies bandpass sampling and is based on the processing of complex‐valued signals by linear‐phase FIR filters, where at any stage of processing the respective signals are always oversampled by two. The simulation results fully confirm the predicted system performance. An electrical demonstration model constructed by cascading six identical specially designed signal processors is being built.
Development of FEC and ESC performance characteristics for IDR carriers greater than 10 Mb/s
Authors: Loureiro Francisco , Koga Keiichiro 
Published: July 2007

AbstractThe requirement for restoration of high capacity fibre optic cables and the new tariffs approved for INTELSAT digital services has created a requirement to develop performance characteristics for IDR carriers greater than 10 Mb/s. This paper presents the trade‐offs used in this development, and estimates the coding gains needed to meet these requirements. A number of FEC schemes are evaluated and a rate 3/4 convolutional code with soft decision Viterbi decoding is selected. Engineering service circuits (ESC) performance characteristics for IDR carriers greater than 10 Mb/s are also presented.
The role of intermediate data rate (IDR) carriers in the intelsat system and their impact upon operational planning
Authors: Roach Peter W. 
Published: July 2007

AbstractIDR carriers will provide a significant proportion of the services in the INTELSAT system within the next few years. A number of factors have been identified which must be considered when developing satellite operational plans, in order to ensure satisfactory operation of an integrated environment consisting of a number of different access techniques and modulation methods.