On 13th october 2017, Adrien-Richard Camboulives has defended his thesis. Awarded by the Paris Saclay University, his work was supervised by both ONERA Châtillon – Département DOTA/Unité Résolution Angulaire laboratory, the doctoral school Onde et Matière n°572 (Paris Saclay University) and IRT Saint Exupéry.
The high quality and the relevance of Adrien-Richard thesis contributed to get significant results as a part of ALBS project.
THESIS SUBJECT
“Mitigation of turbulence effects on ground-to-geostationary link: impact on ground terminal architecture”
About this thesis
An optical link based on a multiplex of wavelengths at 1.55µm is foreseen to be a valuable alternative to the conventional radio-frequencies for the feeder link of the next-generation of high throughput geostationary satellite. Considering the limited power of lasers envisioned for feeder links, the beam divergence has to be dramatically reduced. Consequently, the beam pointing becomes a key issue. During its propagation between the ground station and a geostationary satellite, the optical beam is deflected and possibly distorted by atmospheric turbulence. It induces strong fluctuations of the detected telecom signal, thus reducing the capacity. A steering mirror using a measurement from a beam coming from the satellite is used to pre-compensate the deflection. Because of the point-ahead angle between the downlink and the uplink, the turbulence effects experienced by both beams are slightly different, inducing an error in the correction. The performance criteria is the minimum detectable irradiance 95% of the time. A fast model, named WPLOT, taking into account pointing errors and their temporal evolution, is proposed to evaluate the minimum irradiance as a function of the ground station parameters and quality of the correction. The model’s results are compared to those obtained with a more physical but requiring more computation power: TURANDOT. A sensitivity study has been realized and led to a sizing of a ground station. The model also enables the generation of time series in order to optimize the forward error correction codes in order to be compliant with the targeted capacity (1Terabit/s by 2025).
ALBS PROJECT
Ground processing and transmission chains for RF and optical broadband satellite communication systems (new waveforms, interference and distortions management, ground stations handover, ground optical terminals).
Jury
- V. Michau – Paris-Sud University – PhD Advisor
- A. Belmonte – Technical University of Catalonia, Barcelona Tech – Rapporteur
- Y. Jaouen – Telecom ParisTech – Rapporteur
- M. Tallon- Astrophysical Research Center of Lyon – Examiner
- J. Lacan – ISAE – Examiner
- G. Artaud – CNES – Examiner
- L. Saint-Antonin – IRT Saint Exupéry – Invited
- M-T. Velluet – ONERA – Invited
PUBLICATIONS
- A.-R. Camboulives, M.-T. Velluet, L. Saint-Antonin, S. Poulenard and V. Michau: “Optical ground station optimization for future optical geostationary satellite feeder uplinks”. Photonics West 2017, San Francisco (USA). 2017