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Schaefer S.,University of Kiel | Gregory M.,TESAT Spacecom | Rosenkranz W.,University of Kiel
Optics InfoBase Conference Papers | Year: 2016

We present experimental results for intradyne detection as an alternative for current homodyne systems in optical inter-satellite links. Our approach is based on digital frequency offset and phase noise compensation for more flexible coherent systems. © OSA 2016.


Gregory M.,Tesat Spacecom | Heine F.,Tesat Spacecom | Kampfner H.,Tesat Spacecom | Lange R.,Tesat Spacecom | And 2 more authors.
Optical Engineering | Year: 2012

Laser communication terminals with data rates far above 1 Gbps have been in operation in orbit since January 2008, and the links established between two low Earth orbit (LEO) satellites have demonstrated error-free communication. Bit error rates better than 10-11 have been achieved without data encoding. Signal acquisition can be reproducibly achieved within a few seconds. After adaptation to larger link separation distances these laser communication terminals will be used in the low earth orbit-geosynchronous satellite (LEO-GEO) link of European data relay satellite (EDRS), the GEO European data relay system. LEO-to-ground and ground-to-LEO links have examined the impact of the atmosphere on such optical links. In the future, high data rate GEO-to-ground links will require ground stations equipped with adaptive optics, which are currently under development. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).


Gregory M.,Tesat Spacecom | Heine F.,Tesat Spacecom | Kampfner H.,Tesat Spacecom | Lange R.,Tesat Spacecom | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Since February 2008 coherent laser communication links are operational in-orbit. Transmitting data at a rate of 5.625 Gbps they verify the capability of laser communication exemplarily in LEO-LEO and Ground-LEO constellations. The LEO-LEO links run with a bit error rate of 10-11. Acquisition typically is closed within seconds. On the basis of these results laser communication terminals are adapted to LEO-GEO links with a still scalable user data rate of 1.8 Gbps. The terminals will be applied in the European data relay system. © 2011 SPIE.


Gregory M.,Tesat Spacecom | Heine F.,Tesat Spacecom | Kampfner H.,Tesat Spacecom | Lange R.,Tesat Spacecom | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Today, coherent optical inter-satellite links are operational in LEO-LEO constellations for more than two years. With data transmitted error free at rate of 5.625 Gbps and links established within a few seconds they prove a performance well suited for commercial applications. For the first time coherent LEO-to-ground links have been built up, too. They allow to investigate the atmosphere's impact on optical space-to-ground links for later optimization of optical ground stations. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Schaefer S.,University of Kiel | Rosenkranz W.,University of Kiel | Gregory M.,TESAT Spacecom
2015 IEEE International Conference on Space Optical Systems and Applications, ICSOS 2015 | Year: 2015

In order to increase the data rate and lower the power consumption in satellite communication systems, optical laser terminals are an attractive alternative to the conventional RF systems. By using optical coherent detection, high receiver sensitivity as well as full signal recovery is achieved. However, the local oscillator at the receiver requires a carrier recovery system. In order to achieve homodyne detection, an optical phase-locked loop can be used. Each optical PLL structure is fixed to a specific modulation format and its complexity increases with modulation order. Therefore, applying an intradyne detection scheme, where the local laser runs un-synchronized and frequency offset and phase noise compensation is done by digital signal processing after the optical front end, seems to be a possible alternative. We present numerical results for both coherent detection schemes and compare them in terms of receiver sensitivity. © 2015 IEEE.


Jaumann G.,TESAT Spacecom
2016 IEEE International Vacuum Electronics Conference, IVEC 2016 | Year: 2016

The traditional way to operate TWTAs in orbit is with the helix protection disabled. The pro's and con's of this tradition are discussed hereafter. © 2016 IEEE.


Jaumann G.,TESAT Spacecom
Proceedings of 2015 IEEE International Vacuum Electronics Conference, IVEC 2015 | Year: 2015

TESAT presents an update of the achieved reliability of its TWTAs and MPMs in orbit with data up to the end of the year 2014. Various breakdowns such as SINGLE vs. DUAL units or TWTAs vs. MPMs are presented and discussed. A comparison with the standard reliability analysis based on parts count/stress indicates significantly better reliability in orbit. © 2015 IEEE.


Motzigemba M.,TESAT Spacecom
Proceedings of the International Astronautical Congress, IAC | Year: 2013

The trend of a constantly growing demand for high data transfer caused by high performance sensors on Spacecrafts for Earth Observation Missions and the need of fast information update are looking for new solutions. Critical missions will not wait for the next download of LEO data-to-ground stations after next orbit. The combination of Laser Communication between Satellites for high data transmission and the use of a GEO data relay system for reducing the latency time of data refresh, are real game changers. Optical inter-satellite communication has been verified in orbit. Optical links between two LEO satellites achieved bit error rates better than 10"" at a data rate of 5.625 Gbps. Based on that success, DLR and ESA are fostering the realization of a GEO relay service with the PPP Program EDRS, the European data relay system. EDRS will offer by optical communication a data rate of 1.8 Gbps between LEO and GEO Relay. First customer on the LEO part is the GMES Global Monitoring Environmental System with the Sentinel Spacecrafts. The permanent GEO-to-ground link is based on radio frequency communication (Ka-Band @ 26 GHz) for a reliable, commercial service performance through the atmosphere. The improvement of using such a hybrid (Laser communication and RF) system is not only a high data rate service-Fiber in Space - it is offering an extreme reduction of latency time for the information availability with at the same time commercial service conditions. ©2013 by the International Astronautical Federation. All rights reserved.


Friederichs L.,Satellite Communications | Sterr U.,Satellite Telecommunications Consulting | Dallmann D.,Tesat Spacecom
Journal of Lightwave Technology | Year: 2016

Starting November 2007 and continuing through the present, Tesat-Spacecom has been conducting successfully optical intersatellite communication links utilizing laser communication payloads built by Tesat-Spacecom under DLR funding. A total of four communication payloads are in space at the time of writing. Also optical space-to-ground communication links have been successfully conducted using a compatible ground terminal built by Tesat-Spacecom and the ESA Optical Ground Station on Tenerife. All terminals are using a beaconless spatial acquisition algorithm which was developed by Tesat-Spacecom for intersatellite communication links. We present an analytical investigation on the influence of vibrations deferring the laser beam search pattern on the receiving probability of the counter terminal. A Gaussian distribution of the vibrations is assumed. Results are presented here and compared to computer simulations to verify the analytical results. The influence of link margin and slave terminal position in the scan field on hit probability is addressed. © 2016 IEEE.


Jimenez E.G.,TESAT Spacecom | Jaumann G.,TESAT Spacecom
14th IEEE International Vacuum Electronics Conference, IVEC 2013 - Proceedings | Year: 2013

TESAT presents the achieved reliability of its TWTAs and MPMs in orbit. Various breakdowns such as SINGLE vs. DUAL units or TWTAs vs. MPMs are presented and discussed. A comparison with the standard reliability analysis based on parts count/stress indicates significantly better reliability in orbit. © 2013 IEEE.

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