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  • 1
    Electronic Resource
    Electronic Resource
    Satellite ATM for broadband ISDN (1995)
    Springer
    Telecommunication systems 4 (1995), S. 119-131 
    Details
    ISSN: 1572-9451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper presents the development of satellite ATM for broadband ISDN based on the Research in Advanced Communications in Europe (RACE) CATALYST project. The purpose of the project is to develop an experimental ATM satellite link for the future B-ISDN services, particularly for the interconnections of the ATM testbeds which are in the form of broadband islands developed in Europe. Then initial ATM based B-ISDN can be introduced by interconnections of these broadband islands. An evolutionary approach has been adopted in the development of the ATM networks that the CATALYST project has developed the equipment to be able to interconnect the newly developed ATM testbeds as well as the existing networks such as DQDB, FDDI and Ethernet networks. In March 1994, the project carried out an experiment on the second demonstratoras the Laboratories of Alcatel Telespace in Nanteere near Paris to demonstrate the capability of the satellite ATM connections supporting data, voice, video and multimedia applications. This experiment provided a real system demonstration of satellite ATM for B-ISDN. In the light of the experiment, this paper presents the model and architecture of the ATM satellite equipment, studies the relevant issues and the impact of ATM-via-satellite on the applications and the protocols, and evaluates of satellite ATM based on some measured and simulated results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02110082
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Multiple scattering effects in electromagnetic wave propagation through a medium containing precipitation (1978)
    Institute of Physics
    Details
    Publication Date: 1978-04-01
    Print ISSN: 0305-4470
    Electronic ISSN: 1361-6447
    Topics: Mathematics , Physics
    Published by Institute of Physics
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    PAPER CURRENT
  • 3
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    Frequency scaling propagation parameters using dual-polarization radar results (1984)
    American Geophysical Union
    Details
    Publication Date: 1984-01-01
    Print ISSN: 0048-6604
    Electronic ISSN: 1944-799X
    Topics: Geosciences , Physics
    Published by American Geophysical Union
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    PAPER CURRENT
  • 4
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    A UT positioning approach for dynamic satellite constellations (1995)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: In this paper, we discuss a new positioning scheme which is thought to be applicable for dynamic satellite constellations. We begin with the introduction of our filter model which is based on stochastic process and filtering theory. Then, simulation results of the technique are presented based on a LEO constellation and some of the IRIDIUM system parameters. Performance of this algorithm is investigated under various noise conditions. Finally, several applications of this UT (user terminal) positioning algorithm are discussed.
    Keywords: Spacecraft Design, Testing and Performance
    Type: Proceedings of the Fourth International Mobile Satellite Conference (IMSC 1995); 35-41; NASA-CR-199955
    Format: text
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  • 5
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    Satellite diversity and its implications on the RAKE receiver architecture for CDMA-based S-PCN's (1995)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: In this paper we examine the applicability of RAKE receivers in a mobile LEO satellite channel and identify the potential problem areas. We then proceed to investigate the possibility of a coherent combining architecture (downlink) in the presence of satellite diversity. We closely examine the path delay difference statistics of a diversity channel and propose a delay compensation scheme for the downlink in order to reduce the complexity of the user terminal. Finally, the required modifications to the conventional RAKE receiver are proposed and discussed.
    Keywords: Communications and Radar
    Type: Proceedings of the Fourth International Mobile Satellite Conference (IMSC 1995); 457-462; NASA-CR-199955
    Format: text
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  • 6
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    Narrowband and wideband characterisation of satellite mobile/PCN channel (1995)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper presents models characterizing satellite mobile channel. Statistical narrowband models based on the CSER high elevation angle channel measurement campaign are reported. Such models are understood to be useful for communication system simulations. It has been shown from the modelling results that for the mobile satellite links at high elevation angles line-of-sight (LOS) signal is available most of the time, even under the heavy shadowing conditions. Wideband measurement campaign which CSER is about to undertake, and subsequently the modelling approach to be adopted is also discussed. It is noted that a wideband channel model is expected to provide a useful tool in investigating CDMA applications.
    Keywords: Communications and Radar
    Type: Proceedings of the Fourth International Mobile Satellite Conference (IMSC 1995); 128-133; NASA-CR-199955
    Format: text
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  • 7
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    A variable rate speech compressor for mobile applications (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: One of the most promising speech coder at the bit rate of 9.6 to 4.8 kbits/s is CELP. Code Excited Linear Prediction (CELP) has been dominating 9.6 to 4.8 kbits/s region during the past 3 to 4 years. Its set back however, is its expensive implementation. As an alternative to CELP, the Base-Band CELP (CELP-BB) was developed which produced good quality speech comparable to CELP and a single chip implementable complexity as reported previously. Its robustness was also improved to tolerate errors up to 1.0 pct. and maintain intelligibility up to 5.0 pct. and more. Although, CELP-BB produces good quality speech at around 4.8 kbits/s, it has a fundamental problem when updating the pitch filter memory. A sub-optimal solution is proposed for this problem. Below 4.8 kbits/s, however, CELP-BB suffers from noticeable quantization noise as a result of the large vector dimensions used. Efficient representation of speech below 4.8 kbits/s is reported by introducing Sinusoidal Transform Coding (STC) to represent the LPC excitation which is called Sine Wave Excited LPC (SWELP). In this case, natural sounding good quality synthetic speech is obtained at around 2.4 kbits/s.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, California Inst. of Tech., Proceedings of the 2nd International Mobile Satellite Conference (IMSC 1990); p 690-695
    Format: application/pdf
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  • 8
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    A high quality voice coder with integrated echo canceller and voice activity detector for mobile satellite applications (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In the last decade, low bit rate speech coding research has received much attention resulting in newly developed, good quality, speech coders operating at as low as 4.8 Kb/s. Although speech quality at around 8 Kb/s is acceptable for a wide variety of applications, at 4.8 Kb/s more improvements in quality are necessary to make it acceptable to the majority of applications and users. In addition to the required low bit rate with acceptable speech quality, other facilities such as integrated digital echo cancellation and voice activity detection are now becoming necessary to provide a cost effective and compact solution. In this paper we describe a CELP speech coder with integrated echo canceller and a voice activity detector all of which have been implemented on a single DSP32C with 32 KBytes of SRAM. The quality of CELP coded speech has been improved significantly by a new codebook implementation which also simplifies the encoder/decoder complexity making room for the integration of a 64-tap echo canceller together with a voice activity detector.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the Third International Mobile Satellite Conference (IMSC 1993); p 449-454
    Format: application/pdf
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  • 9
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    Interworking and integration of the Inmarsat Standard-M with Pan-European GSM system (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The market demand on mobile telephone communications has been increasing since the introduction of the cellular mobile telephone systems about twelve years ago. In Europe, projections indicate a demand of about 17 million subscribers for a fully deployed Pan European system. The Pan-European GSM system is to harmonize the growth of the terrestrial mobile system. Studies conducted by the European Space Agency (ESA) indicate that even with 60-70 percent of the area being covered by the GSM, a significant traffic demand (voice and data) will still exist for areas not covered by the terrestrial systems. This demand could be satisfied by a land mobile satellite system. The satellite system is therefore seen in a complementary role rather than in competition with the terrestrial system in an integrated telecommunications network. One possible scenario may be that initially the satellite system provides services to the rural areas together with areas still not covered by the GSM system. This service area is then gradually diminished as the terrestrial system expands until an optimum point is reached where the systems co-exist optimally. The objective of this paper is to investigate the possibility of integration of a space based system, in this case Inmarsat Standard-M, with the GSM (Global System for Mobile communications). One very important advantage of incorporating GSM services in Standard-M is that it will be feasible to extend the GSM services economically worldwide, not only to land mobiles but also to aeronautical and maritime mobiles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, Proceedings of the Third International Mobile Satellite Conference (IMSC 1993); p 131-136
    Format: application/pdf
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  • 10
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    A propagation experiment for modelling high elevation angle land mobile satellite channels (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This paper summarizes the results of a feasibility study for conducting high elevation angle propagation experiments in the European region for land mobile satellite communication. The study addresses various aspects of a proposed experiment. These include the selection of a suitable source for transmission, possibility of gathering narrow and wide band propagation data in various frequency bands, types of useful data, data acquisition technique, possible experimental configuration, and other experimental details.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL, California Inst. of Tech., Proceedings of the 2nd International Mobile Satellite Conference (IMSC 1990); p 231-238
    Format: application/pdf
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