| 1. |
- Browne Mwakyanjala, Moses, 1986-
(författare)
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A Software-Defined Baseband for Satellite Ground Operations : Feasibility and Design
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Satellite telemetry, tracking, and command (TT&C) is a crucial activity needed to maintainthe health of a spacecraft or sometimes to facilitate payload data download. TT&Cground operations are facilitated by a communication device known in the TT&C communityas a baseband. State-of-the-art baseband systems currently in the market haveseveral financial and technical limitations. Financial drawbacks include high capital expenditure,operational expenditure, maintenance costs, and high upgrade costs, whiletechnical limitations include both upgradability and scalability.This thesis presents the feasibility study of a software-defined baseband (SDB) as aviable alternative to existing basebands. The SDB considered here is implemented on aradio architecture that consists of a general-purpose processor for performing radio functionsand low-cost commercial-off-the-shelf, software-defined radio frontends for signalsampling. The research questions focus on the feasibility and design aspects of this SDB.This thesis approaches the design of the SDB with a software development cyclethat involves functional analysis (design), verification, and validation of the radio functionsconstituting the SDB system. The radio functions are the telemetry receiver andthe telecommand transmitter. Functional analysis is performed through functional flowblock diagrams. The verification process is performed through simulations that take intoaccount realistic channel impairments for missions operating in the S-band and characterizedby the Consultative Committee for Space Data Systems (CCSDS) as category Amissions (less than 2 million km). Validation is performed on a laboratory testbed andseveral orbiting satellites.Through the above software development cycle, the telemetry receiver and telecommandtransmitter are developed using the open-source GNU radio development kit. Modulationschemes, line codes, and filters along with CCSDS forward error correction codescommonly employed in TT&C communications are successfully designed, verified in simulations,and validated in a hardware testbed. The performance results from the validationtests demonstrate that it is feasible to implement the SDB TT&C radio functions on theadopted radio architecture.Finally, this thesis investigates in detail the novel concept of multiple spacecraft peraperture (MSPA) that enables communication with several spacecraft from a single antenna.It focuses on in-band interference and out-of-band emissions arising from radiatingmultiple telecommand links from a low-cost SDR frontend. An MSPA transceiver is successfullydeveloped and integrated into the SDB system. Validation tests show that itis feasible for the integrated MSPA transceiver to radiate two telecommand links whileconforming to spectral regulations.
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| 2. |
- Browne Mwakyanjala, Moses, et al.
(författare)
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Concurrent development and verification of an all‐software baseband for satellite ground operations
- 2020
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Ingår i: International Journal of Satellite Communications And Networking. - : John Wiley & Sons. - 1542-0973 .- 1542-0981. ; 38:2, s. 209-227
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Tidskriftsartikel (refereegranskat)abstract
- Communication systems are adopting all‐software architectures, because of their scalability, extensibility, flexibility, and cost‐effectiveness. This paper introduces a concurrent approach to the development and verification of baseband systems for satellite ground operations based on the behaviour‐driven development methodology. The open‐source GNU Radio development kit is used for developing the software‐defined radio baseband signal processing, as well as simulating the satellite and realistic channel impairments. The system performance at the end shows deviations of less than 1 dB with respect to the ideal performance and the Green Book standards specified by the Consultative Committee for Space Data Systems.
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| 3. |
- Browne Mwakyanjala, Moses, et al.
(författare)
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Feasibility of using a software-defined baseband for multiple space per aperture (MSPA) ground operations
- 2022
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Ingår i: International Journal of Satellite Communications And Networking. - : John Wiley & Sons. - 1542-0973 .- 1542-0981. ; 40:2, s. 133-147
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the feasibility of performing multiple spacecraft per aperture (MSPA) ground operations by using a low-cost software-defined baseband (SDB). The SDB is a Consultative Committee for Space Data Systems (CCSDS)-compliant baseband that employs a personal computer for signal processing and a low-cost commercial-off-the-shelf RF front end for RF signal sampling. The SDB is customized to offer traditional telemetry, tracking, and command (TT&C) services for near-Earth missions operating in S band. The study starts by reviewing MSPA methods already studied by space agencies such as NASA and ESA before going to MSPA methods proposed in the latest CCSDS blue book on RF and modulation systems. The feasibility of operating the CCSDS-proposed multiple uplink carrier MSPA method using the SDB is assessed after evaluating in-band interference and out-of-band emissions from the uplink signals radiated by the low-cost RF front end employed by the SDB. Furthermore, we present a case study where the SDB is used in MSPA operations on a typical solid-state amplifier (SSPA) amplifier typically used in near-Earth missions.
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| 4. |
- Browne Mwakyanjala, Moses, et al.
(författare)
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Functional Analysis of Software-Defined Radio Baseband for Satellite Ground Operations
- 2019
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Ingår i: Journal of Spacecraft and Rockets. - : American Institute of Aeronautics and Astronautics. - 0022-4650 .- 1533-6794. ; 56:2, s. 458-475
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents functional analysis and system specifications of a baseband system using software-defined radio (SDR) technology. The analysis is primarily based on the latest blue-book standards from the Consultative Committee for Space Data Systems (CCSDS). It covers telemetry, telecommand, and ranging, as well as some specifications of the associated physical layers. The SDR-based baseband system is envisioned to support ground operations in the form of a software-as-a-Service (SaaS) private cloud.
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| 5. |
- Browne Mwakyanjala, Moses, et al.
(författare)
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Software-defined radio transceiver for QB50 CubeSat telemetry and telecommand
- 2016
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Ingår i: Proceedings of the 34th AIAA International Communications Satellite Systems Conference (ICSSC 2016). - Reston, Virginia : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the development of a ground system based on software-defined radio for supporting both ground testing and space telemetry and telecommand of one of the nanosatellites in the QB50 mission. The QB50 project is an ongoing European Commission Seventh Framework initiative, which aims at launching a constellation of 50 CubeSats in the lower thermosphere to carry out in-situ scientific measurements. The paper discusses the implementation of amateur radio protocols and telecommunication modulation schemes on the ground system. The system setup, deployment and scheduling are also discussed using two separate ground stations. The use of different software for testing the system is detailed, the results show the operability of the developed ground system. © 2016, American Institute of Aeronautics and Astronautics Inc
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| 6. |
- Browne Mwakyanjala, Moses, et al.
(författare)
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Validation of a software-defined baseband system for satellite telemetry and telecommand
- 2021
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Ingår i: International Journal of Satellite Communications And Networking. - : John Wiley & Sons. - 1542-0973 .- 1542-0981. ; 39:6, s. 605-625
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the validation of a software-defined baseband (SDB) system for satellite telemetry and telecommand (TM/TC). The baseband system was developed using the open-source GNU Radio development kit. It runs on a personal computer connected to a commercial-off-the-shelf (CoTS) RF frontend. The validation process was performed by the use of a mission-qualified satellite emulator, a state-of-the-art baseband unit, and orbiting satellites. The baseband is designed to offer multimission support. Hence, it includes a suite of modulation schemes, line codes, matched filters, and Consultative Committee for Space Data Systems (CCSDS) forward error correction codes (convolutional, Reed–Solomon, concatenated, and low-density parity-check [LDPC]) typically employed in TM/TC missions. The figures of merit used for the validation of the TM receiver are bit error rate (BER) and frame error rate (FER). For the TC transmitter, the validated features are modulation index, power spectrum, and the physical layer operations procedures (PLOP).
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| 7. |
- Browne Mwakyanjala, Moses, et al.
(författare)
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Verification of phase and frequency modulation for software-defined radio baseband systems using field data
- 2017
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Ingår i: 35th AIAA International Communications Satellite Systems Conference, ICSSC 2017. - Reston, Virginia : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the verification of phase and frequency modulation schemes for a software-defined radio baseband system that is being prototyped to support satellite telemetry, telecommand and ranging. It presents the theory behind the two modulation schemes, implementation and verification against emulated signals from a space-qualified hardware-based baseband system as well as from the Odin satellite.
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| 8. |
- Elfvelin, Martin, et al.
(författare)
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A flexible ground segment for small satellite operations
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72<sup>nd</sup> International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- With the launch of the first CubeSat a trend of easy access to Low Earth Orbit was started. Today many educational institutes around the world design, build and operate CubeSats for educational as well as scientific purposes. This paper presents designs and development in hardware and software made to achieve a flexible ground segment at the Luleå University of Technology Space Campus in Kiruna, Sweden. The existing ground station is adapted to support more frequencies and modes of operation to enable future satellite projects at the university easy access to space communications. New equipment has been procured and integrated with existing equipment in a new location using a 19-inch server rack. The article presents a ground segment design using software-defined radio to promote flexibility and adaptability. A in-house developed sequence control board is presented that enables the ground station to quickly switch between full duplex and half-duplex modes.
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