Manfred Wittig

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Telecommunications Missions based on Nanosatellites

An Integrated Satellite Communication System for Data Relay, Mobile Communication and Disaster Communications

57th International Astronautical Congress, Oct 2, 2006

Reliable Optical Wireless Links used as feeder links between earth and satellite

The use of optical communication links is a growing and promising technology, with its applicatio... more The use of optical communication links is a growing and promising technology, with its applications spreading over many areas of telecommunication. ESA&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s involvement in the development of optical communication terminals for high data rate links between satellites already resulted in the successful demonstration of the SILEX programme using optical inter-satellite links, using the ARTEMIS satellite in the GEO orbit and

Developments towards an Interplanetary Internet

ABSTRACT A major effort in current developments for future space missions is the improvement of c... more ABSTRACT A major effort in current developments for future space missions is the improvement of communications capabilities. With increasing interest in space research and long-term exploration programs including a variety of both near Earth and deep space missions of the major space agencies, communications faces additional challenges. Next-generation communication systems must be able to cope with long-distance communication links, supporting disruption-tolerant networking (DTN), implementing efficient store-and-forward strategies for data download, and providing interoperability between missions. Therefore, innovative concepts for the creation of an Interplanetary Internet (IPN) are currently under investigation. The Interplanetary Internet Special Interest Group (IPNSIG) has already elaborated a suitable IPN network architecture and identified key research areas. Since the main challenges for IPN are efficient data transport strategies, current research activities are focused on the transport layer. However, in order to achieve these goals, improvements at all OSI layers are necessary. The presented paper deals with future developments required for the establishment of an Interplanetary Internet. After introducing an IPN network architecture proposed by, the suitability of terrestrial Internet and existing space communications standards for IPN is analyzed. Current protocol developments for IPN are introduced and compared with the previously investigated standards. Finally, future IPN developments are presented. This analysis focuses on all OSI layers, providing a set of recommendations for the improvement of existing technologies and proposing some innovative concepts and solutions.

Large-capacity multimedia satellite systems

IEEE Communications Magazine, 1997

The exponential growth of Internet use may result in a reduction of the grade of service of telec... more The exponential growth of Internet use may result in a reduction of the grade of service of telecommunication networks. Capacity increase is the challenge to telecom operators. Communication satellites "see" a large customer population and provide a large: amount of-mainly entertainment-information. Interactive services are possible with enhanced communication satellite systems. Such satellite concepts and technologies are the subject of this article.

Large-capacity multimedia systems

IEEE Communications Magazine, Jul 1, 1997

OPS-SAT Phase A/B1: Development and AIV Plan

OPS-SAT- A Novel Concept

OPS-SAT Phase A/B1: Experiment Analysis

OPS-SAT Phase A/B1: Mission Requirements Document

Activities of the European Space Agency in the Field of Optical Space Communication

The European Space Agency ESA is developing an optical inter-orbit communication system enabling ... more The European Space Agency ESA is developing an optical inter-orbit communication system enabling a link between a low-Earth orbiting (LEO) and a geostationary spacecraft (GEO). This so-called SILEX system allows a transmission of 50 Mbps from LEO to GEO in an experimental and pre-operational mode. The system uses GaAlAs laser diodes operating at 60 mW average power and direct detection. Both terminals are in the main development phase C/D. The terminals will be launched on board the ESA satellite ARTEMIS and the French satellite SPOT 4 with nominal launch dates in 1996 and 1995, respectively. A fully operational data relay satellite DRS 1 will be launched in 1999 to complement the European data relay infrastructure. Apart from the SILEX project the Agency has investigated advanced system concepts to optimize the terminals and to fulfil the data rate requirements of future Earth observation instruments. Results of system studies and ongoing R&D activities in the areas of high-power NdYAG lasers and coherent receivers are presented.

Impact Of Satellite Motion On Optical Intersatellite Data Links: A System Simulation Approach

Proceedings of SPIE, Sep 18, 1987

ABSTRACT Digital satellite communication links are usually characterized by transmission capacity... more ABSTRACT Digital satellite communication links are usually characterized by transmission capacity, link distance, bit error rate, availability, and lifetime. For optical data links, however, an additional parameter, the burst error rate has to be specified. The physical reason for the occurrence of burst errors lies in the required precise mutual tracking of both satellite communication terminals. The influence of the statistical motion of both satellites around their nominal attitude on optical data link performance has been studied by computer simulations. Improvements achievable with forward error correcting coding are analyzed. These simulation results are based on a Gaussian distribution of independently vibrating satellites.

Small Optical User Terminal for Intersatellite Communications

Springer eBooks, 1994

The European Space Agency (ESA) has programmes underway to place data relay satellites (DRS) in g... more The European Space Agency (ESA) has programmes underway to place data relay satellites (DRS) in geostationary orbit (GEO) within the next decade. The first satellite to fly will be Artemis which will carry a SILEX optical data relay terminal with a single 50 Mbps optical channel, followed by the operational European Data Relay System (EDRS) which will also carry SILEX terminals. Once these elements of Europe’s DRS infra-structure are in place, there will be a need for optical communications terminals on low Earth orbiting (LEO) satellites (user terminals) capable of transmitting data to the GEO DRS terminals. ESA initiated a development programme in 1992 for a LEO optical terminal with a 2 Mbps data rate. This Small Optical User Terminal (SOUT) has distinctive features of low mass, small size, and compatibility with SILEX. The prime contractor is British Aerospace, with the Canadian companies CAL and Spar, and the Belgian company Spacebel as major subcontractors.

The Importance Of Pointing-Acquisition And Tracking For Optical Communication Payloads

Proceedings of SPIE, Oct 6, 1989

The pointing, acquisition and tracking (PAT) subsystem is a very substantial part of a free-space... more

Internet access for everybody: The satellite solution

Acta Astronautica, 2009

Download

<title>Flight configuration for the small optical user terminal</title>

Proceedings of SPIE, Aug 16, 1994

The Small Optical User Terminal (SOUl) is an optical communications package for interconnecting a... more The Small Optical User Terminal (SOUl) is an optical communications package for interconnecting a LEO satellite to future optical data relay terminals and is the subject of an ESA development programme led by British Aerospace. The baseline terminal has a data rate of 2 Mbps over the return inter-orbit link and a mass of around 25 kg. Special features include a periscopic coarse pointing assembly, refractive telescope, passive anti-vibration mount, combined acquisition and tracking sensor, and fibre coupled lasers and receivers. The flight configuration which allows these features to be combined in a compact unit is described in this paper. Details are given of the pointing, acquisition and tracking, optical, and thermal and structural subsystems.

$Research paper thumbnail of Diffractive optics for advanced free space laser communication terminals$

Diffractive optics for advanced free space laser communication terminals

... 2.1 Link scenario and system concept Figure 1 shows the possible free space link scenarios ar... more

European SILEX project and other advanced concepts for optical space communications

Proceedings of SPIE, May 1, 1991

The European Space Agency (ESA) is developing an optical inter-orbit communication system enablin... more The European Space Agency (ESA) is developing an optical inter-orbit communication system enabling a link between a low earth orbiting (LEO) and a geostationary (GEO) spacecraft. The link allows the transmission of 50 Mbps between LEO and GEO in an experimental and pre-operational mode. The system uses laser diodes of typically 100 mW optical power at a wavelength of 830 nanometer. Direct intensity modulation is applied. Telescopes of 25 cm diameter are used on both terminals. The breadboard phase has been completed and the launch of both terminals is scheduled for 1994. Other concepts for optical space communication links using Nd:YAG lasers and heterodyne receive systems are outlined.

2010 12TH International Conference on Transparent Optical Networks (Icton)

International Conference on Transparent Optical Networks, 2011

<title>European SILEX project: concept, performance, status, and planning</title&gt

Proceedings of SPIE, Jul 1, 1990

The European Space Agency (ESA) is developing an optical interorbit communication system enabling... more The European Space Agency (ESA) is developing an optical interorbit communication system enabling a link between a low earth orbiting (LEO) and a geostationary (GEO) spacecraft. The link allows the transmission of up to 65 Mbps between LEO and GEO in an experimental and preoperational mode. The system uses laser diodes of typically 100 mW optical power at a wavelength of 830 nanometer. Direct intensity modulation is applied. Telescopes of 25 cm diameter are used on both terminals. The breadboard phase has been completed and the launch of both terminals is scheduled for 1994.

Manfred Wittig

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