Tesat-Spacecom (Germany)

For long-range and high data rate optical inter-satellite links, increasing aperture size or optical output power is necessary to achieve desired performance. However, higher optical power can induce non-linear effects, potentially compromising communication quality. In this study, we present experimental data on the impact of non-linear effects on C-Band communication system with two different signal modulation formats: 2.5G OOK NRZ and 100G DP-QPSK. To that extent, modulated optical signals were amplified up to 40 W using a newly developed high-power optical amplifier and were transmitted through a standard single-mode fiber of varying lengths. As non-linear effects intensified, a decrease in communication sensitivity was measured by the bit error ratio (BER). These results revealed distinct behaviors between the OOK and DP-QPSK systems. The 2.5G OOK system showed no non-linear effects below a certain power threshold, but beyond this threshold, communication was severely impaired. Conversely, the 100G DP-QPSK system-maintained communication even at 40 W of optical output power across all fiber lengths tested, though it experienced some link penalty when the power exceeded 10 W. These findings highlight the importance of understanding and managing non-linear effects in high-power optical inter-satellite communication systems to optimize performance.

We perform single-event effect (SEE) tests with well-characterized fully fragmented (i.e., beyond Bragg peak) high-energy heavy-ion beams and compare the results with those expected from conventional, mono-linear energy transfer (mono-LET) measurements, showing a satisfactory level of agreement between the two. This compliance paves the way for the exploitation of simulation tools for accurately quantifying the ion fragmentation impact on SEE rates for both ground-level testing conditions and space galactic cosmic-ray (GCR) environments, with electronics operating behind significant thicknesses of shielding. The satisfactory agreement level is also encouraging in view of the possible usage of fragmented heavy-ion beams for ground-level SEE testing of electronics.

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 88.730 data relay links executed (status Aug 2024), we report on the successful inter-satellite operation of the SDA compatible SCOT80 LCTs on Kepler S/Cs and share recent results. In addition, we present the status on our access terminal SCOT30, targeting the small LEO user segment. Our intradyne development activities have been continued and the algorithms have been further optimized for the atmospheric turbulent channel. We will share the latest results and findings.

Phased array antennas play an increasing role in everyday life. They are a key technology to increase the network capabilities of 5G and 6G and are becoming a crucial component of satellite communication. In space, they are deployed in different orbits for various use cases which results in a wide performance range and requires a variety of antenna designs. Hence, a modular and scalable approach for a phased array antenna is presented to tackle the problem of designing various antennas to serve different orbits and missions. The Ethernet Antenna is a phased array antenna with 64 elements which is a modular building block for larger arrays. The necessary performance per use case is met by using an appropriate number of building blocks and by selecting the proper modules which requires only limited effort for redesign. This paper demonstrates that this approach results in an antenna design that meets the requirements of various orbits and use cases while coping with different satellite platforms.

Nowadays, the key to success for modules is to increase their integration level on the next step. The phased array antenna within the project, "Very Low Latency Satellite Communication System" jumps up onto the step to enhance its performance with low resource requirements at the same time. It is not just a simple antenna, it is actually a complete communication system for digital data, which is assembled on a single printed circuit board. The two antennas for receiving and transmitting belong to the central elements within the module design as well as a digital part for beamforming and signal processing. In this paper, this system is presented with focus on a receiving patch antenna, an element of the 6 x 8 phased array that receives a circular polarized wave in a frequency band of about 100 MHz, with a center frequency of 29.7 GHz. As the payload module, the communication system, with its antennas, stands up to the challenges resulting from the spacecraft, a 3U+ CubeSat deployed in the Very Low Earth Orbit (VLEO). A primary target of the mission is to transmit data with low latency and to achieve up to 100 Mbit/s in downlink and 10 Mbit/s in uplink between a ground station and the VLEO satellite system.

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The growth of satellite constellations necessitates versatile data forwarding for IP packets. This paper proposes an architecture and an implementation of a redundant, space-grade, router architecture for IP packet routing based on Open vSwitch. The architecture is designed to be resilient against individual hardware failures and enables QoS routing capabilities as well as traffic prioritization. This approach permits IP routing on cost effective commercial hardware while retaining reliability.

We present the European development of an engineering model Laser Head for LISA. This single box includes a seed laser, an electro-optical phase modulator, a fiber amplifier and all PCBs to operate the Laser Head.

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.

The sensitivity of the LM139A quad voltage comparator toward simultaneous single-event transient has been investigated through laser single photon absorption. The results have been supported and compared to heavy-ion tests. The analysis of sensitivity leads to the observation of two sensitive cases related to internal charge-sharing mechanism between comparator function and input line coupling effects.