DLR.de Chart 1 DLR s Optical Communications Program for 2018 and beyond Dr. Sandro Scalise Institute of Communications and Navigation
DLR.de Chart 3 Relevant Scenarios Unidirectional Links Main application areas Earth observation Deep space missions Inter-Satellite Links Mainly LEO GEO Mature and reliable technology with TRL 9 (EDRS, Tesat LCT) Direct Earth-Ground Links for LEO satellites esp. small LEOs (50 to 500 kg) For Cubesats Bidirectional Links Main application areas Telecom GNSS (for time transfer)? Inter-Satellite Links HAPs Mega-Constellations LEOs maybe MEOs? Galileo 2-3G? Feeder Links for GEOs
DLR.de Chart 4 DLR OSIRIS Program Optical Space Infrared Downlink System OSIRISv1 & OSIRISv2 in Orbit (on Flying Laptop & BIROS) Cubesat-Version in Orbit by 2018 OSIRISv3 in Orbit by 2019 Further OSIRIS-payloads to be launched in 2019
DLR.de Chart 5 OSIRIS Development Roadmap Launch 2017 2016 OSIRISv1: Open-Loop Body Pointing Data rate: up to 200 Mbit/s OSIRISv2: Closed-Loop Body Pointing with Tracking Sensor Data rate: up to 1 Gbit/s OSIRIS4CubeSat: Active Beam Steering combined with body pointing Data rate: up to 100 Mbit/s 2018 2019 Commercialization Phase together with: OSIRISv3: Active Beam Steering with Coarse Pointing Assembly Data rate: up to 10 Gbit/s
DLR.de Chart 6 OSIRISv1 on Flying Laptop Concept Satellite Bus: University of Stuttgart Dimension: 80 x 60 x 50 cm Mass: 120 kg Launch: July 14 th, 2017 System Parameters: Laser 1: 200 Mbit/s with 1W Laser 2: 78 Mbit/s with 125 mw Power and weight: 26 W, 1,3 kg Pointing: Open-Loop Body Pointing Flying Laptop (FLP)
DLR.de Chart 7 OSIRISv2 on BiROS Concept Satellite Bus: DLR Berlin Adlershof Dimension: 88 x 65 x 55 cm Mass: 115 kg Launch: June 22 nd, 2016 System Parameters: Laser 1: 1 Gbit/s with 1W Laser 2: 150 Mbit/s with 150mW Power and weight: 37 W, 1,65 kg Tracking Sensor with optical uplink channel (1 Mbit/s) Pointing: Closed-Loop Body Poiting Bispectral Infrared Optical System (BiROS)
DLR.de Chart 8 OSIRISv2 Flight Model BiROS satellite, DLR Berlin
DLR.de Chart 9 OSIRISv3 under Development Concept Modular system concept to adapt to different missions and spacecraft needs Commercialization partner: Tesat Spacecom Designed for 5 years lifetime in orbit Equipped with a dedicated Coarse Pointing Assembly (CPA) unit Data handling + storage included in the OSIRIS terminal Optical uplink channel System Parameters: Weight: 5 kg Power consumption: 50 W (operation), 10 W (Stand-By) Downlink data rate: N x 10 Gbit/s Reference implementation for upcoming CCSDS-standard
DLR.de Chart 10 OSIRIS4CubeSat under Development Concept Miniaturized OSIRIS version for cubesat platforms Highly compact system design COTS components based on OSIRIS space qualification Demonstration mission in 2018 Commercialization partner: Tesat Spacecom System Parameters: Size: 90 x 95 x 35 mm (~0,3U) Weight: < 300g Power consumption: < 8W Downlink data rate: 100 Mbit/s
DLR.de Chart 13 Optical Ground Station Oberpfaffenhofen Optimized for scientific measurements 80 cm telescope with coudé room by 2018 Adaptive Optics by 2019
DLR.de Chart 14 Transportable Optical Ground Station Optimized for data reception 60 cm telescope Worldwide use with short lead-time
DLR.de Chart 15 Optical GEO Feeder Links: Motivation Currently HT GEO Satellites: Ka-Band (user + feeder) Next steps: extensions to Q/V and W bands for feeder-links ( few extra-ghz) Number of required gateways increases linearly with throughput Approach: Optical Feeder Links 10-12 OGSs for cloud mitigation Every gateway provides full capacity DWDM Technology from fiber communication Several THz of bandwidth and no-regulation
DLR.de Chart 16 Technological Challenges Ground-Segment Site availability vs. connectivity Fast switching / handover Optical Link Challenging channel esp. in the uplink (atmospheric turbulences) Pre-distortion adaptive optics Transmitter diversity Space-Segment (optical RF Payload) Power & mass budget Heat dissipation Space qualified HW High-speed ADCs and DACs DWDM components Optical pre-amplification First Step: Demonstrate DWDM Technology in relevant environment
DLR.de Chart 17 THRUST (Terabit throughput satellite system technology) Project Ground link emulating the GEO feeder link Environment defined by the atmospheric turbulence (C n 2 profile) 10,45 km link between DLR-Weilheim and DWD Hohenpeißenberg Measurement of the communications performance with strong fluctuations Channel characterization DLR-Weilheim 10.45 km DWD-Hohenpeißenberg
DLR.de Chart 18 THRUST: Hardware Setup for Fiber Coupling Satellite terminal with single-mode fiber coupling Telescope FSM VIS / IR T99 / R01 VIS CAM 4QD Optics Signal coupling Electronics Sensor analysis Actuator control SMF Filter Iris RX IR CAM
DLR.de Chart 19 THRUST: Hardware on the Field during the Demonstration Measurement campaign in October 2016 TX: DLR Weilheim Alignment Laser seen from DWD - Hohenpeißenberg RX: DWD - Hohenpeißenberg
DLR.de Chart 20 THRUST: Test Campaign with Bit Error Ratio Measurements Characterization of the power fluctuations and BER for each channel Measurements performed in several turbulence conditions Measured functionality in worst-case channel turbulence 1.72 Tbit/s transmitted with 40 DWDM channels in optical C-Band (Worldwide Record!)
DLR.de Chart 22 Coherent Optical Communications Coherent modulation schemes Higher spectral efficiency Better sensitivity Digital homodyne receiver No need of OPLL Digital signal processing Robust to signal fading Technology demonstrated in GEO-equivalent turbulent environment 10.45 km worst-case channel conditions for GEO link 30 Gbit/s BPSK demonstrated in October 2016 40 Gbit/s BPSK demonstrated in June 2017 Signal processing optimized for the turbulent channel Surof, J.; Poliak, J. & Mata Calvo, R., Demonstration of intradyne BPSK optical free-space transmission in representative atmospheric turbulence conditions for geostationary uplink channel, Opt. Lett., OSA, 2017, 42, 2173-2176
DLR.de Chart 24 Next Steps towards First In-Orbit Demonstration Definition of the end-to-end communications system Compatibility and interface with RF standards (DVB-S2X/RCS) Modulation, coding, error correction approach Definition of a suitable payload architecture Analog transparent vs. fully digital regenerative (many options in between) Trade-off complexity / robustness Development of a robust coherent optical communication system Higher sensitivity and more robust to channel impairments Optimization of the post-processing for the atmospheric channel Development of channel impairments mitigation techniques Adaptive optics: for downlink wave-front conjugation and uplink pre-distortion Blind transmitter-diversity schemes Laser Guide Stars for uplink channel estimation Collaboration with ESO/ESA in joint measurement campaigns
DLR.de Chart 25 Summary & Conclusions Optical LEO Satellite Downlinks Two payloads in orbit, further payloads planned Currently developed systems enable downlink rates of 10 Gbps Higher data rates / Smaller terminals ( Cubesat) under development Standardisation within CCSDS ongoing Optical GEO Feeder Links DLR demonstrated DWDM technology in a representative environment DLR raised the record in free-space optical transmission rate to 1.72 Tbps Demonstration of 40 Gbit/s BPSK (with only one wavelength) Goal is the first experimental demonstration by 2020-2021 in cooperation with industrial partners thanks for more than 20 years of experience and heritage in optical freespace communications for space applications, DLR developments and early prototypes are an excellent basis for product development through our industrial partners
DLR.de Chart 26 DLR s Optical Communications Program for 2018 and beyond Acknowledgments: Christian Fuchs, Dr. Dirk Giggenbach, Dr. Ramon Mata Calvo, Florian Moll, Christopher Schmidt and all the rest of DLR team working on the subject