ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR ... more ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR Forschungsinstituts für Kommunikation und Navigation und dessen Forschungspro-jekten. Er zeigt außerdem die Entwicklung zu einem ge-samtheitlichen Projektmanagementkonzept für das Institut für Kommunikation und Navigation auf und gibt einen Ausblick auf weitere Ziele und Maßnahmen.
ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR ... more ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR Forschungsinstituts für Kommunikation und Navigation und dessen Forschungspro-jekten. Er zeigt außerdem die Entwicklung zu einem ge-samtheitlichen Projektmanagementkonzept für das Institut für Kommunikation und Navigation auf und gibt einen Ausblick auf weitere Ziele und Maßnahmen.
Breadboard model of a coherent optical BPSK homodyne system with virtual pilot tone (ViP)-based r... more Breadboard model of a coherent optical BPSK homodyne system with virtual pilot tone (ViP)-based receiver and MRC auxiliary channel. [Proceedings of SPIE 3932, 35 (2000)]. Florian David, Christoph Rapp. Abstract. This paper presents a bread-board model of an optical BPSK ...
Proceedings of Spie the International Society For Optical Engineering, Jul 1, 2003
Within the frame of the FASOLT project the German Aerospace Center (DLR) performed channel measur... more Within the frame of the FASOLT project the German Aerospace Center (DLR) performed channel measurements and optical data transmission tests on a 61 km near ground horizontal path. The transmitter was situated on a mountain top in the German Alps with the receiver placed on top of a building at the DLR site in Oberpfaffenhofen. Partners in the FASOLT project were Contraves Space, Switzerland and EADS Military Aircraft, Germany. During a period of several months various data sets of scintillation data were recorded in one and two laterally separated transmitter configurations and under different environmental conditions. A significant decrease of number and depth of fades was observed for the two transmitter setup. This paper presents an overview on the scintillation statistics of this particular optical channel. Also beam offsets due to refraction have been measured and results are presented here. As well as these measurements, data transmission tests at bit rates of 100 Mbps have been performed. A two transmitter configuration with a transmit power of 1 W per laser and a sensitive APD receiver front-end plugged in to a 75mm Rx telescope have been used. Despite severe scintillations, bit error rates (BER) below 1e-4 could be observed, though synchronization losses of the data and clock recovery affected the results. Tests at 155 Mbps (OC-3) and 270 Mbps (SMPTE 259M) were not successful due to high atmospheric attenuation. This paper gives an overview of the entire experimental setup, sums up the results of this long-haul data transmission experiment, and gives an outlook to further DLR activities in the field of free-space optics.
ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary hi... more ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary high altitude platform (HAP) systems, where communications platforms are placed in the stratosphere at altitudes between 20 and 30 km and are kept stationary. Situated over congested urban areas they will be capable of handling high data rate traffic like a geostationary satellite. Due to the specific altitudes of these platforms, communications cross links between either two platforms are not as severely affected by Earth´s atmosphere, as near-ground links are. Hence this scenario is very well-suited for optical inter-platform communications. Nevertheless such optical links suffer from various atmospheric influences that we will discuss here. In particular this paper addresses intensity fluctuations due to atmospheric turbulence, atmospheric attenuation due to absorption and scattering, and background radiation. Platform vibrations and according mispointing and –tracking losses are regarded as well. It turns out that possible links distances are very much limited by vibrations, scintillations and background light. The terminal design is generally a trade-off between those effects. From an extensive investigation of all influence factors, hints for the design of optical cross links in HAP systems will be given in terms of suitable transmitter divergence angles and receiver field of view. Link budget calculations clearly prove the feasibility of optical cross links. However, they as well show the limitations to optical communications in this particular application.
Optics in Atmospheric Propagation and Adaptive Systems VII, 2004
Research activities at the German Aerospace Center (DLR) concerning optical free-space communicat... more Research activities at the German Aerospace Center (DLR) concerning optical free-space communications have focussed on coherent communication systems for inter-satellite link (ISL) applications for a long time. Under DLR contract Tesat Spacecom has developed the DLR-LCT (laser communications terminal) which relies on coherent technology. This terminal will be verified in space as secondary payload onboard the earth observation satellite TerraSAR-X,
Emerging Location Aware Broadband Wireless Ad Hoc Networks, 2005
... of users (both, signaling and data traffic coming from satellite terminals, satellite gateway... more ... of users (both, signaling and data traffic coming from satellite terminals, satellite gateways, and Network Control Center), to process ... of usage for ATC purposes will start from less safety-critical applications such as crew communications, general airline operational control, and bi ...
Optics in Atmospheric Propagation and Adaptive Systems VII, 2004
Atmospheric refraction bends optical beams and lets objects appear in positions they not really a... more Atmospheric refraction bends optical beams and lets objects appear in positions they not really are. This phenomenon is very important in astronomy. However, astronomical refraction formulas can only be used if the light source is at a very far distance from the observer. Then, atmospheric refraction mainly depends on meteorological conditions on ground. In case of optical free-space communications, the distances are comparatively short and well-known formulas for astronomical refraction are no longer sufficient. An exact knowledge of the structure of the whole atmosphere is required to assess refraction in this case. Due to the complexity of the atmosphere, analytical solutions are not possible. Hence, a numerical simulation model based on spherical symmetry, atmospheric shell modeling and standard atmosphere models was used instead. Three different categories of refraction were examined: 1) the observer is situated on ground and the object is at an altitude of at least 25 km, 2) both object and observer are below 25 km and the link path is mainly vertical and 3) both object and observer are in the stratosphere and ray paths are mainly horizontal. The results presented in this work are useful for applications like laser beam pointing and satellite tracking, UAV (Unmanned Aerial Vehicle) and HAP (High Altitude Platform) downlinks or long-haul cross-links through the atmosphere, e.g. HAP-HAP or UAV-satellite.
Free-Space Laser Communication Technologies XII, 2000
ABSTRACT This paper presents a bread-board model of an optical BPSK homodyne system. A new phase ... more ABSTRACT This paper presents a bread-board model of an optical BPSK homodyne system. A new phase synchronization method--the so- called Virtual Pilot-tone method--enables a dramatic reduction of the system completely. Although fully compatible to the transmit signal of a high data rate Costas Loop system, the receiver design is enormously simplified. Neither an optical 90 degree(s) hybrid nor digital high speed electronics are needed. An additional low data rate auxiliary channel is provided by using a Modulated Residual Carrier and envelope detection.The data rate of this auxiliary channel has to be well below that of the main channel, but is sufficient for transmitting e.g. telemetry data. Both methods and their realization are explained. Simulation and practical results are displayed and compared to a standard Costas Loop design.
Genome engineering based on homologous recombination has been applied to yeast for many years. Ho... more Genome engineering based on homologous recombination has been applied to yeast for many years. However, the growing importance of yeast as a cell factory in metabolic engineering and chassis in synthetic biology demands methods for fast and efficient introduction of multiple targeted changes such as gene knockouts and introduction of multistep metabolic pathways. In this review, we summarize recent improvements of existing genome engineering methods, the development of novel techniques, for example for advanced genome redesign and evolution, and the importance of endonucleases as genome engineering tools.
Industrial bio-processes for fine chemical production are increasingly relying on cell factories ... more Industrial bio-processes for fine chemical production are increasingly relying on cell factories developed through metabolic engineering and synthetic biology. The use of high throughput techniques and automation for the design of cell factories, and especially platform strains, has played an important role in the transition from laboratory research to industrial production. Model organisms such as Saccharomyces cerevisiae and Escherichia coli remain widely used host strains for industrial production due to their robust and desirable traits. This review describes some of the bio-based fine chemicals that have reached the market, key metabolic engineering tools that have allowed this to happen and some of the companies that are currently utilizing these technologies for developing industrial production processes.
Free-Space Laser Communication Technologies XVI, 2004
When designing free-space optics systems, one key issue is to assess the impact of scintillations... more When designing free-space optics systems, one key issue is to assess the impact of scintillations and to find an appropriate link margin to cope with atmospheric fading. Huge effort is spent to find mathematical models to describe laser beam propagation through the atmosphere. However, these models are quite cumbersome to use for the communications engineer. On the other hand, there
Free-Space Laser Communication Technologies XV, 2003
Channel measurements were performed by the German Aerospace Center in various near ground optical... more Channel measurements were performed by the German Aerospace Center in various near ground optical channels including a 1.5 km horizontal path as well as a 61km path. These measurements clearly showed that the atmosphere causes very slow fading (compared to the high data rates usually used in optical communication systems), which significantly degrades the transmission quality. As transmitter power and
22nd AIAA International Communications Satellite Systems Conference & Exhibit 2004 (ICSSC), 2004
ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary hi... more ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary high altitude platform (HAP) systems, where communications platforms are placed in the stratosphere at altitudes between 20 and 30 km and are kept stationary. Situated over congested urban areas they will be capable of handling high data rate traffic like a geostationary satellite. Due to the specific altitudes of these platforms, communications cross links between either two platforms are not as severely affected by Earth´s atmosphere, as near-ground links are. Hence this scenario is very well-suited for optical inter-platform communications. Nevertheless such optical links suffer from various atmospheric influences that we will discuss here. In particular this paper addresses intensity fluctuations due to atmospheric turbulence, atmospheric attenuation due to absorption and scattering, and background radiation. Platform vibrations and according mispointing and –tracking losses are regarded as well. It turns out that possible links distances are very much limited by vibrations, scintillations and background light. The terminal design is generally a trade-off between those effects. From an extensive investigation of all influence factors, hints for the design of optical cross links in HAP systems will be given in terms of suitable transmitter divergence angles and receiver field of view. Link budget calculations clearly prove the feasibility of optical cross links. However, they as well show the limitations to optical communications in this particular application.
ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR ... more ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR Forschungsinstituts für Kommunikation und Navigation und dessen Forschungspro-jekten. Er zeigt außerdem die Entwicklung zu einem ge-samtheitlichen Projektmanagementkonzept für das Institut für Kommunikation und Navigation auf und gibt einen Ausblick auf weitere Ziele und Maßnahmen.
ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR ... more ABSTRACT Dieser Beitrag beschreibt die Anforderungen an das Pro-jektmanagement innerhalb des DLR Forschungsinstituts für Kommunikation und Navigation und dessen Forschungspro-jekten. Er zeigt außerdem die Entwicklung zu einem ge-samtheitlichen Projektmanagementkonzept für das Institut für Kommunikation und Navigation auf und gibt einen Ausblick auf weitere Ziele und Maßnahmen.
Breadboard model of a coherent optical BPSK homodyne system with virtual pilot tone (ViP)-based r... more Breadboard model of a coherent optical BPSK homodyne system with virtual pilot tone (ViP)-based receiver and MRC auxiliary channel. [Proceedings of SPIE 3932, 35 (2000)]. Florian David, Christoph Rapp. Abstract. This paper presents a bread-board model of an optical BPSK ...
Proceedings of Spie the International Society For Optical Engineering, Jul 1, 2003
Within the frame of the FASOLT project the German Aerospace Center (DLR) performed channel measur... more Within the frame of the FASOLT project the German Aerospace Center (DLR) performed channel measurements and optical data transmission tests on a 61 km near ground horizontal path. The transmitter was situated on a mountain top in the German Alps with the receiver placed on top of a building at the DLR site in Oberpfaffenhofen. Partners in the FASOLT project were Contraves Space, Switzerland and EADS Military Aircraft, Germany. During a period of several months various data sets of scintillation data were recorded in one and two laterally separated transmitter configurations and under different environmental conditions. A significant decrease of number and depth of fades was observed for the two transmitter setup. This paper presents an overview on the scintillation statistics of this particular optical channel. Also beam offsets due to refraction have been measured and results are presented here. As well as these measurements, data transmission tests at bit rates of 100 Mbps have been performed. A two transmitter configuration with a transmit power of 1 W per laser and a sensitive APD receiver front-end plugged in to a 75mm Rx telescope have been used. Despite severe scintillations, bit error rates (BER) below 1e-4 could be observed, though synchronization losses of the data and clock recovery affected the results. Tests at 155 Mbps (OC-3) and 270 Mbps (SMPTE 259M) were not successful due to high atmospheric attenuation. This paper gives an overview of the entire experimental setup, sums up the results of this long-haul data transmission experiment, and gives an outlook to further DLR activities in the field of free-space optics.
ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary hi... more ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary high altitude platform (HAP) systems, where communications platforms are placed in the stratosphere at altitudes between 20 and 30 km and are kept stationary. Situated over congested urban areas they will be capable of handling high data rate traffic like a geostationary satellite. Due to the specific altitudes of these platforms, communications cross links between either two platforms are not as severely affected by Earth´s atmosphere, as near-ground links are. Hence this scenario is very well-suited for optical inter-platform communications. Nevertheless such optical links suffer from various atmospheric influences that we will discuss here. In particular this paper addresses intensity fluctuations due to atmospheric turbulence, atmospheric attenuation due to absorption and scattering, and background radiation. Platform vibrations and according mispointing and –tracking losses are regarded as well. It turns out that possible links distances are very much limited by vibrations, scintillations and background light. The terminal design is generally a trade-off between those effects. From an extensive investigation of all influence factors, hints for the design of optical cross links in HAP systems will be given in terms of suitable transmitter divergence angles and receiver field of view. Link budget calculations clearly prove the feasibility of optical cross links. However, they as well show the limitations to optical communications in this particular application.
Optics in Atmospheric Propagation and Adaptive Systems VII, 2004
Research activities at the German Aerospace Center (DLR) concerning optical free-space communicat... more Research activities at the German Aerospace Center (DLR) concerning optical free-space communications have focussed on coherent communication systems for inter-satellite link (ISL) applications for a long time. Under DLR contract Tesat Spacecom has developed the DLR-LCT (laser communications terminal) which relies on coherent technology. This terminal will be verified in space as secondary payload onboard the earth observation satellite TerraSAR-X,
Emerging Location Aware Broadband Wireless Ad Hoc Networks, 2005
... of users (both, signaling and data traffic coming from satellite terminals, satellite gateway... more ... of users (both, signaling and data traffic coming from satellite terminals, satellite gateways, and Network Control Center), to process ... of usage for ATC purposes will start from less safety-critical applications such as crew communications, general airline operational control, and bi ...
Optics in Atmospheric Propagation and Adaptive Systems VII, 2004
Atmospheric refraction bends optical beams and lets objects appear in positions they not really a... more Atmospheric refraction bends optical beams and lets objects appear in positions they not really are. This phenomenon is very important in astronomy. However, astronomical refraction formulas can only be used if the light source is at a very far distance from the observer. Then, atmospheric refraction mainly depends on meteorological conditions on ground. In case of optical free-space communications, the distances are comparatively short and well-known formulas for astronomical refraction are no longer sufficient. An exact knowledge of the structure of the whole atmosphere is required to assess refraction in this case. Due to the complexity of the atmosphere, analytical solutions are not possible. Hence, a numerical simulation model based on spherical symmetry, atmospheric shell modeling and standard atmosphere models was used instead. Three different categories of refraction were examined: 1) the observer is situated on ground and the object is at an altitude of at least 25 km, 2) both object and observer are below 25 km and the link path is mainly vertical and 3) both object and observer are in the stratosphere and ray paths are mainly horizontal. The results presented in this work are useful for applications like laser beam pointing and satellite tracking, UAV (Unmanned Aerial Vehicle) and HAP (High Altitude Platform) downlinks or long-haul cross-links through the atmosphere, e.g. HAP-HAP or UAV-satellite.
Free-Space Laser Communication Technologies XII, 2000
ABSTRACT This paper presents a bread-board model of an optical BPSK homodyne system. A new phase ... more ABSTRACT This paper presents a bread-board model of an optical BPSK homodyne system. A new phase synchronization method--the so- called Virtual Pilot-tone method--enables a dramatic reduction of the system completely. Although fully compatible to the transmit signal of a high data rate Costas Loop system, the receiver design is enormously simplified. Neither an optical 90 degree(s) hybrid nor digital high speed electronics are needed. An additional low data rate auxiliary channel is provided by using a Modulated Residual Carrier and envelope detection.The data rate of this auxiliary channel has to be well below that of the main channel, but is sufficient for transmitting e.g. telemetry data. Both methods and their realization are explained. Simulation and practical results are displayed and compared to a standard Costas Loop design.
Genome engineering based on homologous recombination has been applied to yeast for many years. Ho... more Genome engineering based on homologous recombination has been applied to yeast for many years. However, the growing importance of yeast as a cell factory in metabolic engineering and chassis in synthetic biology demands methods for fast and efficient introduction of multiple targeted changes such as gene knockouts and introduction of multistep metabolic pathways. In this review, we summarize recent improvements of existing genome engineering methods, the development of novel techniques, for example for advanced genome redesign and evolution, and the importance of endonucleases as genome engineering tools.
Industrial bio-processes for fine chemical production are increasingly relying on cell factories ... more Industrial bio-processes for fine chemical production are increasingly relying on cell factories developed through metabolic engineering and synthetic biology. The use of high throughput techniques and automation for the design of cell factories, and especially platform strains, has played an important role in the transition from laboratory research to industrial production. Model organisms such as Saccharomyces cerevisiae and Escherichia coli remain widely used host strains for industrial production due to their robust and desirable traits. This review describes some of the bio-based fine chemicals that have reached the market, key metabolic engineering tools that have allowed this to happen and some of the companies that are currently utilizing these technologies for developing industrial production processes.
Free-Space Laser Communication Technologies XVI, 2004
When designing free-space optics systems, one key issue is to assess the impact of scintillations... more When designing free-space optics systems, one key issue is to assess the impact of scintillations and to find an appropriate link margin to cope with atmospheric fading. Huge effort is spent to find mathematical models to describe laser beam propagation through the atmosphere. However, these models are quite cumbersome to use for the communications engineer. On the other hand, there
Free-Space Laser Communication Technologies XV, 2003
Channel measurements were performed by the German Aerospace Center in various near ground optical... more Channel measurements were performed by the German Aerospace Center in various near ground optical channels including a 1.5 km horizontal path as well as a 61km path. These measurements clearly showed that the atmosphere causes very slow fading (compared to the high data rates usually used in optical communication systems), which significantly degrades the transmission quality. As transmitter power and
22nd AIAA International Communications Satellite Systems Conference & Exhibit 2004 (ICSSC), 2004
ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary hi... more ABSTRACT A perspective for future high data-rate communication systems are quasi-geostationary high altitude platform (HAP) systems, where communications platforms are placed in the stratosphere at altitudes between 20 and 30 km and are kept stationary. Situated over congested urban areas they will be capable of handling high data rate traffic like a geostationary satellite. Due to the specific altitudes of these platforms, communications cross links between either two platforms are not as severely affected by Earth´s atmosphere, as near-ground links are. Hence this scenario is very well-suited for optical inter-platform communications. Nevertheless such optical links suffer from various atmospheric influences that we will discuss here. In particular this paper addresses intensity fluctuations due to atmospheric turbulence, atmospheric attenuation due to absorption and scattering, and background radiation. Platform vibrations and according mispointing and –tracking losses are regarded as well. It turns out that possible links distances are very much limited by vibrations, scintillations and background light. The terminal design is generally a trade-off between those effects. From an extensive investigation of all influence factors, hints for the design of optical cross links in HAP systems will be given in terms of suitable transmitter divergence angles and receiver field of view. Link budget calculations clearly prove the feasibility of optical cross links. However, they as well show the limitations to optical communications in this particular application.
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Papers by Florian David