OSIRIS Laser Downlink Terminals for Small LEO Satellites Completed (Closed WGs... · 2012-04-17 ·...

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OSIRIS Laser Downlink Terminals for Small LEO Satellites Dirk Giggenbach, Martin Brechtelsbauer, Christopher Schmidt, Christian Fuchs Institute of Communications and Navigation Optical Communication Systems Group German Aerospace Center (DLR) Oberpfaffenhofen, Germany


OSIRIS Optical Space Infrared Downlink System


Laser Downlink Terminals for Small LEO Satellites Background & Motivation - Experimental validation of fast Optical downlinks for small satellites

(~BIRD-Class, 50x50x50cm³, 50kg)

- Major Benefits of Optical Communications: - Smaller, lighter and lower power

consumption than RF systems - No spectrum regulations issues!

- Data-Rates

- 1 … 10 Gbit/s (Downlink) - few Mbit/s (Uplink)

- Main Goals

- Experimental concept validation - Gathering of Measurement data and validation of ground equipment

(e.g. AO Systems)


Major Challenge: Link-Blockage by Clouds Optical Ground Station Diversity - Example:

4 Optical Ground Stations (OGS) in Germany Combined Availability:

- Summer: 91% - Winter: 73%

- European OGS-Network:

>98% annual Availability (5 Stations) - Worldwide OGS-Networks allow

availabilities over 99%

European and Worldwide OGS-Locations

OGS-Locations in Germany

red/yellow: areas with low/high cloud probability


OSIRIS: Current Developments @ DLR Laser Sources High Power Laser Diode (HPLD) - Weight: ~150 g - Up to 155 Mbit/s @ 0,1 W Optical Power - Power Consumption: ~8 W

Erbium Doped Fiber-Amplifier (EDFA) - Weight: ~1 kg - Up to 2,5 Gbit/s @ 1 W Optical Power - Power Consumption: ~35 W - Space-Qualification ongoing


OSIRIS: Current Developments @ DLR Tracking Devices

Dedicated Pointing Unit - Pointing independent from satellite attitude

- Goal:

- „Coffee Cup“ sized optical comms terminal - < 5 kg - < 50 W (only during downlink)

Tracking Device based on 4QD - Higher pointing accuracy Better link-budget

- Tracking done with satellite

4QD: Four Quadrant Detector

Pointing Unit for aeronautical applications

Basic System Parameters

- Beacon - 1560nm, 2x 5W - Good synergies with other projects, eye-safety - Integrated low-rate uplink (~Mbit/s)

- Downlink

- Current Electronics allow up to 2,5 Gbit/s - Currently limited by On-Board-Computer to 1 Gbit/s - 10 Gbit/s feasible from electronics Point-Of-View

- Coding

- Currently: Standard CCSDS TM/TC-Frames


Development Schedule – Next Steps

- In-Orbit-Validations of… - COTS-EDFA and HPLD (2013) - Tracking Device with integrated uplink (2014)

- Further Developments required

- Space-Proof EDFA - Compact and light-weight Coarse Pointing Assembly (CPA)

- Goal: IoV of experimental optical terminal with CPA: ~2016



Optical Ground Station Oberpfaffenhofen (OGS-OP)

40cm Cassegrain-Telescope

Optical Ground Station Oberpfaffenhofen „Next Generation“

- 4,5m clamshell-dome

- Fits up to 1,5m Telescope

- Coude-Room for Operations and Adaptive Optics


Transportable Optical Ground Station (TOGS)

- 60cm Aluminium-Mirror (Manufactured at DLR)

- Low Weight due to usage of composite materials

- Globally Deployable

- Data-Rates up to 1,25 Gbit/s

- Optimized for aircraft- and satellite-downlinks


Transportable Optical Ground Station (TOGS)

Conclusions

- DLR-IKN is developing experimental optical terminals for small satellites

- Several components and systems are currently in development and will be demonstrated in flight

- Several Optical Ground Stations are available for experiments


OSIRIS Laser Downlink Terminals for Small LEO Satellites Completed (Closed WGs... · 2012-04-17 ·...

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