KEYWORDS: Laser communication terminals, Homodyne detection, Satellites, Receivers, Design, Data transmission, Space operations, Power consumption, Laser communications, Data communications
This paper details the progress in laser communication activities of Tesat-Spacecom. Besides the EDRS program (European Data Relay System) update of in-orbit Laser Communication Terminal (LCT) performance, with more than 81.859 data relay links executed (status Nov 2023), we report on the recent terminal projects, kicked off in 2022/2023. We present recent results of the first intradyne 1064nm coherent laser communication link from space to ground tested between GEO satellite Alphasat and the DLR/TESAT ground station (T-AOGS) at the observatory of Teide in Tenerife, Spain. Furthermore, we share results of intradyne lab measurements. Besides technology demonstrations, we present the new TESAT products in development (SCOT20 and SCOT135), that aim for the Cubesat market on the one hand and the high-performance systems for MEO / GEO satellites with data rates up to 100 Gbps, using commercial COTS technology, on the other hand. Finally, we report on the progress of the SCOT80 terminals delivered for the SDA Tranche 0 program.
The Transportable Adaptive Optical Ground Station, which was located at Tenerife (Spain) from 2014 until 2019 was shipped for a refurbishment and several enhancements to Switzerland. Following the refurbishment, a measurement campaign at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald (Switzerland) was performed, in July/August 2021. The optical counter terminal for the experiments was the TDP1-LCT at the geostationary Alphasat satellite. In the seven weeks of the campaign, measurements for optical uplink communication at a rural site in Europe at an altitude of 900 meters to a GEO spacecraft were gathered. We give an overview of the improvements of the T-AOGS and the actual status after the refurbishment. We present the results of the link activities, e.g. the uplink budget (ground to space) and the dynamic of the atmosphere (scintillations index, number of fades, fade duration).
KEYWORDS: Laser communication terminals, Quantum key distribution, Satellites, Space operations, Free space optics, Quantum data, Power consumption, Laser communications
This paper details the progress in the laser communication activities of Tesat-Spacecom. The EDRS program, the European Data Relay System, a private public partnership program between the European Space Agency ESA and Airbus Defence and Space ADS, is running flawlessly, until now (Oct 2022) 75.000 data relay links have been executed. We report on the performance of the systems in space and detail on other laser comms related activities of TESAT. Especially the delivery and launch of the first optimized LCTs (Laser Communication Terminals) for LEO data relay, the Smart LCTs. In addition, the delivery of Cubesat LCTs have to be mentioned, and the development, qualification and delivery of the ConLCTs for the SDA Tranche 0 program. Furthermore, TESATs involvement in Quantum Key Distribution (QKD) and Precision Navigation and Timing (PNT) programs will be detailed.
An important step towards reliable optical communication between ground and space is the characterization and understanding of atmospheric conditions – even when being at one place and performing links into one direction, but at different times. Within this paper the analysis of five years of optical links from a laser terminal on a geostationary satellite (TDP1-LCT on Alphasat) to ground (T-AOGS at Tenerife) is shown. The data, in total 40.2 h of reliable measurements extracted from 516 performed links, are spread over several times of the year and almost all times of day. For one of the main parameters describing the atmosphere (the Fried Parameter r0) a clear characteristic over the day is validated. For the up-link the influence of different transmitted beam divergence angles on the link budget in terms of mean power and fade statistic is shown. A short outlook on upcoming changes within the TDP-1 software and the TAOGS functionality is given.
After more than 3 years of operational experiences with the Transportable Adaptive Optical Ground Station (T-AOGS) it is not any more the question whether optical communication through atmosphere is possible for Geo to ground applications. It is important to understand the performance of optical communication under different atmospheric-conditions and which the key parameters are to improve simplicity, robustness and availability of optical bi-directional satellite to ground links (SGL). We report within this paper on the characterization of the atmospheric channel for ground to GEO optical communication without adaptive optics correction in the uplink. Besides the telemetry data of the space segment and the T-AOGS, also a special measurement campaign was carried out using the 1m telescope of the ESA-OGS in parallel. An outlook for further analysis and activities is given.
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