31, August 2020

ESA Open Invitation to Tender AO10451
Open Date: 27/08/2020
Closing Date: 20/11/2020 13:00:00

Status: ISSUED
Reference Nr.: 20.1TI.07
Prog. Ref.: OP-Other Act. CC
Budget Ref.: E/0534-05A – OP-Other Act. CC
Tender Type: C
Price Range: > 500 KEURO
Products: Satellites & Probes / Optical Communication / Optical Comm ¿ BB / Laser sources, modulators / Satellites & Probes / Optical Communication / Optical Comm ¿ BB / Software
Technology Domains: Optoelectronics / Laser Technologies / Laser Sources
Establishment: ESTEC
Directorate: Directorate Telecom & Integrated Applica
Department: Telecom Technologies,Product&Systems Dep
Division: Institutional and European Programme Off
Contract Officer: Glandieres, Florence Odette Jeanne
Industrial Policy Measure: N/A – Not apply
Last Update Date: 27/08/2020
Update Reason: Tender issue

The objective of this activity is to design, manufacture and test a transmitter that demonstrates the critical functionsof variabledata rate (VDR) optical communications in direct-to-Earth links from LEO spacecraft. Targeted Improvements: A three-fold increase of the data return (volume) during the full pass of a LEO satellite over the ground station compared to the state-of-the-art fixed data rate terminals. Description: An area of significant interest for applying optical communications is high-rate telemetry downlinksfrom low Earth orbit (LEO) satellites directly to Earth (DTE) for both institutional and commercial missions. This scenario is currently being standardised by CCSDS and referred to as optical on-off keying (O3K) due to the binary pulsed modulation used. The channel data rates considered in O3K range from a few Mbps to 10 Gbps. Even in the absence of cloud blockage, optical LEO DTE links are limited in their data rate by the turbulence of the atmospheric refraction index, which is highly dependent on the elevation angle. So far, optical LEO DTE links have been of experimental nature, trying to achieve attractive data rates with small satellites, limited resources, and low complexity. In this framework, the transmitter employs a single data rate during the whole pass of the LEO spacecraft over the optical ground station. However, this is a worst-case approach that does not allow the transmitter to operate in a more robust regime at lower elevation angles, and, at the same time, prevents the transmitter from using its full potential in terms of data rate at higher elevation angles. In contrast, state-of-the-art radiofrequency (RF) LEO DTE make use of severalmodulation schemes throughout a full pass over the receiving ground station to maximise the data through put as a function of the elevation angle and channel conditions. Variable data rate has not been yet implemented in optical LEO DTE downlinks. Its introduction would enable the optimisation of the transmission rate in each segment of the LEO pass -instead of accepting a worst-case, lower through-put scenario-, making the technology much more competitive with respect to the RF option.

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