TerraSAR-X LCT-ATM

• Optical downlink from the LEO satellite TerraSAR-X in the second half of 2007
• Data rate 5.6Gbps (BPSK).
• Atmospheric measurements with a Turbulence Profiler and a DIMM

TX-Wavelength 1064 nm TX- Power 1W TX-Aperture D 12.4cm RX-Aperture D 40cm DLR, 12.4cm Tesat Data Rate 5.6Gbps BPSK Distance 500-1000km Elevation Angles 30-90deg.

The laser communication terminal in the test-bed.

In the framework of the TerraSAR-X- Mission the DLR Laser Communication Terminal (LCT) is planned to be verified in several downlink experiments to the optical ground station in Oberpfaffenhofen (OGS-OP).

The LCT is planned to be launched on TerraSAR-X mid 2007 to demonstrate highest bitrates for downlinks and inter-satellite optical links. The terminal is based on coherent technology at 1064nm with BPSK at 5.6Gbps.

First tests will take place in downlinks to the optical ground station at Oberpfaffenhofen in the second half of 2007. DLR has developed several instruments to measure atmospheric turbulence (Atmospheric Transmission Monitor ATM) in parallel to the data transmission and the bit error measurements. The Turbulence Profiler estimates the turbulence on the path through the atmosphere, the so called Cn2 profile. The Differential Image Motion Monitor (DIMM) measures the atmospheric coherence length r0 on the path.

Project Duration: 2004 - 2007

Web-page on Optical Communications : http://www.kn.dlr.de/freespaceoptics/

Publications :

N. Perlot, M. Knapek, D. Giggenbach, J. Horwath, M. Brechtelsbauer, Y. Takayama, T. Jono, "Results of the Optical Downlink Experiment KIODO from OICETS Satellite to Optical Ground Station Oberpfaffenhofen (OGS-OP)," SPIE Photonics West, Free Space Laser Communication Technologies XIX, San Jose, Jan. 2007. pdf

M. Knapek, J. Horwath, N. Perlot and B. Wilkerson, “The DLR Ground Station in the Optical Payload Experiment (STROPEX) - Results of the Atmospheric Measurement Instruments”, Proceedings of the SPIE 2006, Vol. 6304. pdf

Joachim Horwath, Florian David, Markus Knapek, Nicolas Perlot, “Coherent transmission feasibility analysis,” Free-Space Laser Communication Technologies XVII; G. Stephen Mecherle; Ed., Proc. SPIE Vol. 5712, p. 13-23., April 2005. pdf

Example of gathered turbulence data. Recorded turbulence profiler pupil intensity snapshot of the 40 cm Cassegrain telescope aperture with central obscuration (left). Recorded DIMM sample picture, with the two focal spots moving against each other (right).