2020 International Conference on Broadband Communications for Next Generation Networks and Multimedia Applications (CoBCom)
The PRETTY mission is a satellite mission of the European Space Agency (ESA) with the goal to dem... more The PRETTY mission is a satellite mission of the European Space Agency (ESA) with the goal to demonstrate the concept of passive reflectometry with a small and cost-efficient 3U Nanosatellite. Passive reflectometry allows the characterisation of the Earth surface properties and height, by correlating direct and reflected Global Positioning System (GPS) signals. The PRETTY mission focuses on the characterisation of the surface height. The system is realized as a Software Defined Radio (SDR) with a high-gain GPS patch antenna array that receives the very weak reflected signals from Earth’s surface. The GPS patch antenna array resides on the outer surface of the satellite with direct contact to the harsh space environment. The application in space is a key factor for many requirements and design restrictions for the PRETTY GPS antenna array. This paper focuses on the various design constraints and requirements for the antenna array and describes the relations with the antenna design parameters. The paper describes the results obtained from a first single patch simulation and discusses the final antenna array architecture, simulation results and PCB design.
In the framework of two nanosatellite projects with European Space Agency a versatile platform co... more In the framework of two nanosatellite projects with European Space Agency a versatile platform consisting of a powerful processor based on a system-on-chip-module with a large field-programmable array (FPGA) and a software-defined radio (SDR) front-end was developed by TU Graz and the SME UniTel. The SDR module covers a frequency range from 300 to 6000 MHz. These two units constitute a flexible transceiver for small LEO satellites, suitable both for LEO-to-ground links, but also for inter- satellite links for LEO constellations. Without extra converters S- and C-band can be accommodated directly. The design was made flexible such that X-, Ku- and Ka-band can be utilised as well by using adapter boards containing the LNAs, SSPAs and frequency converters for these bands. Special care was taken in the PCB layouting to guarantee a very high performance and to minimise EMC effects. UniTel recently developed an add-on module with special hardware encryption. Due to the optimised PCB layou...
2020 International Conference on Broadband Communications for Next Generation Networks and Multimedia Applications (CoBCom), 2020
OPS-SAT is a 3U CubeSat, designed for versatile use as an experimental platform for industry and ... more OPS-SAT is a 3U CubeSat, designed for versatile use as an experimental platform for industry and universities, to demonstrate new operational concepts and prototype software in a real space environment. The satellite offers numerous payloads alongside the satellite bus, all of which might be used by an OPS-SAT experiment. The unpredictable nature of experiments with respect to the use of payload components raises certain unknowns, in particular concerning power consumption. As a result, the thermal behaviour throughout the satellite depends largely on which of the several on-board experiments and the associated payloads are switched on. OPS-SAT offers a variety of communication modules, such as a UHF transceiver, an S-Band transceiver, a Software Defined Radio (SDR), an X-Band transmitter and an optical receiver. The peak power consumption of OPS-SAT may exceed 30 watts during high power experiments. The S-Band transceiver consumes up to 10 watts during ground station passes and the so-called Satellite Experimental Processing Platform (SEPP), the heart of OPS-SAT experiments, consumes up to 8 watts constantly. This work provides an overview of the design and the thermal considerations on OPS-SAT and the results of the thermal vacuum (TVAC) test campaign. The results yield an average thermo-optical emissivity of 0.79 to 0.84 and the thermal power distribution on the spacecraft surface, and demonstrate the special case of the thermally isolated S-Band and X-Band patch antennas. Based on the derived results, predictions can be made about the thermal behaviour during various load cases and during periods with an active S-Band transmitter.
e & i Elektrotechnik und Informationstechnik, 2022
OPS-SAT is an ESA nanosatellite launched in December 2019. The spacecraft is open for third-party... more OPS-SAT is an ESA nanosatellite launched in December 2019. The spacecraft is open for third-party experiments, which can use almost all functions provided by the spacecraft and take full control of it. Depending on the experiment and usage of the payload, the power consumption of the spacecraft may be as small as a few watts but can exceed 30 W at full load. The peak power production lies in the same order of magnitude, which is highly demanding for thermal regulation. This article describes the preparation and execution of the OPS-SAT Thermal Vacuum (TVAC) test campaign and discusses the limitations and restrictions that had to be taken into account, such as technical limitations with respect to mounting the spacecraft inside the TVAC chamber. Additionally, the procedure of identifying a comprehensive test scenario is discussed. The general approach of TVAC tests and the results of one full test cycle are presented, and the key findings are discussed. The goal is to address the pro...
e & i Elektrotechnik und Informationstechnik, 2022
The space industry is one of today’s major growth markets and a very interesting business sector ... more The space industry is one of today’s major growth markets and a very interesting business sector for innovation, science, and technology. In the last century, the space industry has dramatically changed and undergone strong commercialization referred to as “New Space”. In addition to the commercialization, the concept of CubeSats has become well established in the market during the last decade. The European Space Agency (ESA) has acknowledged this trend and uses CubeSat nanosatellites for projects like the OPS-SAT mission. OPS-SAT uses state-of-the-art embedded systems for various tasks. These embedded systems are the key for the great mission success of OPS-SAT and provide outstanding computational power for various experiments conducted with the OPS-SAT flying laboratory. This paper describes the fundamental design of these embedded systems and discusses some of the related achievements during the OPS-SAT mission.
2020 International Conference on Broadband Communications for Next Generation Networks and Multimedia Applications (CoBCom), 2020
After the successful launch of the ESA OPS-SAT Nanosatellite in December 2019, the Institute of C... more After the successful launch of the ESA OPS-SAT Nanosatellite in December 2019, the Institute of Communication Networks at Graz University of Technology (TUG) has started its work on a new second-generation Software Defined Radio (SDR) transceiver platform for the ESA PRETTY mission. The mission goal of PRETTY is the demonstration of the passive reflectometry concept with an SDR on a 3U Nanosatellite. The PRETTY satellite requires a powerful second-generation SDR receiver that extends the functionality and performance of the first-generation SDR used for OPS-SAT. There are many lessons learned about the first-generation SDR characteristics, the performance, ease of use and the strengths but also the weaknesses of the design during the OPS-SAT environmental and functional testing campaign. The second-generation SDR design considers the experiences from the first-generation SDR and implements several improvements for the thermal behavior, mechanical sustainability, device control and status monitoring in order to achieve higher overall performance and reliability. The second-generation SDR uses an AD9361 radio frequency (RF) frontend chip, that allows the signal reception with two independent receive channels and signal transmission with two independent transmit channels. In particular, the new transmit functionality of the second-generation SDR is a remarkable improvement compared to the first-generation SDR for OPSSAT, due to its full-duplex, bidirectional communication capabilities. Further improvements provide the possibility, to extend the design with RF mixer boards, to achieve the flexibility required for future applications on higher RF bands.
2020 International Conference on Broadband Communications for Next Generation Networks and Multimedia Applications (CoBCom)
The PRETTY mission is a satellite mission of the European Space Agency (ESA) with the goal to dem... more The PRETTY mission is a satellite mission of the European Space Agency (ESA) with the goal to demonstrate the concept of passive reflectometry with a small and cost-efficient 3U Nanosatellite. Passive reflectometry allows the characterisation of the Earth surface properties and height, by correlating direct and reflected Global Positioning System (GPS) signals. The PRETTY mission focuses on the characterisation of the surface height. The system is realized as a Software Defined Radio (SDR) with a high-gain GPS patch antenna array that receives the very weak reflected signals from Earth’s surface. The GPS patch antenna array resides on the outer surface of the satellite with direct contact to the harsh space environment. The application in space is a key factor for many requirements and design restrictions for the PRETTY GPS antenna array. This paper focuses on the various design constraints and requirements for the antenna array and describes the relations with the antenna design parameters. The paper describes the results obtained from a first single patch simulation and discusses the final antenna array architecture, simulation results and PCB design.
In the framework of two nanosatellite projects with European Space Agency a versatile platform co... more In the framework of two nanosatellite projects with European Space Agency a versatile platform consisting of a powerful processor based on a system-on-chip-module with a large field-programmable array (FPGA) and a software-defined radio (SDR) front-end was developed by TU Graz and the SME UniTel. The SDR module covers a frequency range from 300 to 6000 MHz. These two units constitute a flexible transceiver for small LEO satellites, suitable both for LEO-to-ground links, but also for inter- satellite links for LEO constellations. Without extra converters S- and C-band can be accommodated directly. The design was made flexible such that X-, Ku- and Ka-band can be utilised as well by using adapter boards containing the LNAs, SSPAs and frequency converters for these bands. Special care was taken in the PCB layouting to guarantee a very high performance and to minimise EMC effects. UniTel recently developed an add-on module with special hardware encryption. Due to the optimised PCB layou...
2020 International Conference on Broadband Communications for Next Generation Networks and Multimedia Applications (CoBCom), 2020
OPS-SAT is a 3U CubeSat, designed for versatile use as an experimental platform for industry and ... more OPS-SAT is a 3U CubeSat, designed for versatile use as an experimental platform for industry and universities, to demonstrate new operational concepts and prototype software in a real space environment. The satellite offers numerous payloads alongside the satellite bus, all of which might be used by an OPS-SAT experiment. The unpredictable nature of experiments with respect to the use of payload components raises certain unknowns, in particular concerning power consumption. As a result, the thermal behaviour throughout the satellite depends largely on which of the several on-board experiments and the associated payloads are switched on. OPS-SAT offers a variety of communication modules, such as a UHF transceiver, an S-Band transceiver, a Software Defined Radio (SDR), an X-Band transmitter and an optical receiver. The peak power consumption of OPS-SAT may exceed 30 watts during high power experiments. The S-Band transceiver consumes up to 10 watts during ground station passes and the so-called Satellite Experimental Processing Platform (SEPP), the heart of OPS-SAT experiments, consumes up to 8 watts constantly. This work provides an overview of the design and the thermal considerations on OPS-SAT and the results of the thermal vacuum (TVAC) test campaign. The results yield an average thermo-optical emissivity of 0.79 to 0.84 and the thermal power distribution on the spacecraft surface, and demonstrate the special case of the thermally isolated S-Band and X-Band patch antennas. Based on the derived results, predictions can be made about the thermal behaviour during various load cases and during periods with an active S-Band transmitter.
e & i Elektrotechnik und Informationstechnik, 2022
OPS-SAT is an ESA nanosatellite launched in December 2019. The spacecraft is open for third-party... more OPS-SAT is an ESA nanosatellite launched in December 2019. The spacecraft is open for third-party experiments, which can use almost all functions provided by the spacecraft and take full control of it. Depending on the experiment and usage of the payload, the power consumption of the spacecraft may be as small as a few watts but can exceed 30 W at full load. The peak power production lies in the same order of magnitude, which is highly demanding for thermal regulation. This article describes the preparation and execution of the OPS-SAT Thermal Vacuum (TVAC) test campaign and discusses the limitations and restrictions that had to be taken into account, such as technical limitations with respect to mounting the spacecraft inside the TVAC chamber. Additionally, the procedure of identifying a comprehensive test scenario is discussed. The general approach of TVAC tests and the results of one full test cycle are presented, and the key findings are discussed. The goal is to address the pro...
e & i Elektrotechnik und Informationstechnik, 2022
The space industry is one of today’s major growth markets and a very interesting business sector ... more The space industry is one of today’s major growth markets and a very interesting business sector for innovation, science, and technology. In the last century, the space industry has dramatically changed and undergone strong commercialization referred to as “New Space”. In addition to the commercialization, the concept of CubeSats has become well established in the market during the last decade. The European Space Agency (ESA) has acknowledged this trend and uses CubeSat nanosatellites for projects like the OPS-SAT mission. OPS-SAT uses state-of-the-art embedded systems for various tasks. These embedded systems are the key for the great mission success of OPS-SAT and provide outstanding computational power for various experiments conducted with the OPS-SAT flying laboratory. This paper describes the fundamental design of these embedded systems and discusses some of the related achievements during the OPS-SAT mission.
2020 International Conference on Broadband Communications for Next Generation Networks and Multimedia Applications (CoBCom), 2020
After the successful launch of the ESA OPS-SAT Nanosatellite in December 2019, the Institute of C... more After the successful launch of the ESA OPS-SAT Nanosatellite in December 2019, the Institute of Communication Networks at Graz University of Technology (TUG) has started its work on a new second-generation Software Defined Radio (SDR) transceiver platform for the ESA PRETTY mission. The mission goal of PRETTY is the demonstration of the passive reflectometry concept with an SDR on a 3U Nanosatellite. The PRETTY satellite requires a powerful second-generation SDR receiver that extends the functionality and performance of the first-generation SDR used for OPS-SAT. There are many lessons learned about the first-generation SDR characteristics, the performance, ease of use and the strengths but also the weaknesses of the design during the OPS-SAT environmental and functional testing campaign. The second-generation SDR design considers the experiences from the first-generation SDR and implements several improvements for the thermal behavior, mechanical sustainability, device control and status monitoring in order to achieve higher overall performance and reliability. The second-generation SDR uses an AD9361 radio frequency (RF) frontend chip, that allows the signal reception with two independent receive channels and signal transmission with two independent transmit channels. In particular, the new transmit functionality of the second-generation SDR is a remarkable improvement compared to the first-generation SDR for OPSSAT, due to its full-duplex, bidirectional communication capabilities. Further improvements provide the possibility, to extend the design with RF mixer boards, to achieve the flexibility required for future applications on higher RF bands.
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Papers by Andreas Hörmer