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Theses

Techniques de synchronisation à très faible SNR pour des applications satellites

Mohamed Amine Jhaidri 1, 2
2 Lab-STICC_IMTA_CACS_COM
Lab-STICC - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance
Abstract : In deep space communication systems, the long distance between the spacecraft and the ground station along with the limited capacity of the on-board power generator result a very low signal to noise ratio (SNR). However, such transmission still possible by using near Shannon limit error correction codes (Turbo code and LDPC code). Nevertheless, to take advantage of this coding gain, the coherent demodulation is mandatory, and the carrier phase synchronization must be reliable at more restrictive SNR. At very low SNR, current synchronization systems are limited and unable to provide the required performances. Our goal is to improve the reliability of the receiver synchronization stage under very difficult conditions of a very low SNR, a variable Doppler effect (Doppler rate) and a blind transmission. This thesis deals with the problem of carrier phase synchronization for the downlink of a Deep Space transmission. After the study of the existing solutions, we selected the phase locked loop (Phase Locked Loop: PLL). In an industrial context, PLL offers the best trade-off between complexity and performance. Several phase detectors based on the maximum likelihood criterion were considered and characterized by their S-curves. Based on the equivalent models, we have developed a new study of the non-linear acquisition phase of a second-order PLL with a semi-sinusoidal phase error detector. The second part of the thesis was dedicated to the antennas combining techniques. These methods aim to improve the link budget of the transmission and offer more flexibility. At the end of this part, we proposed a new antennas combining scheme that improves the operating threshold of existing systems.
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Submitted on : Wednesday, June 13, 2018 - 2:29:06 PM
Last modification on : Friday, September 25, 2020 - 3:35:57 AM

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  • HAL Id : tel-01814702, version 1

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Mohamed Amine Jhaidri. Techniques de synchronisation à très faible SNR pour des applications satellites. Traitement du signal et de l'image [eess.SP]. Ecole nationale supérieure Mines-Télécom Atlantique, 2017. Français. ⟨NNT : 2017IMTA0038⟩. ⟨tel-01814702⟩

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