DelfiC3 communications subsystem design

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Delfi-C3 communications subsystem design

• Reaching out to the radio amateur community

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Who am I

• Wouter Jan Ubbels, MSc Student
• PE4WJ
• Delfi-C3 Communications
• W.J.Ubbels_at_delfic3.nl
• TU Delft, Aerospace Engineering
• Space Systems Engineering and Technology

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Contents

• Delfi-C3 Mission
• Delfi-C3 Communications subsystem design
• Space segment
• Advanced transceiver
• AMSAT platform
• Frequency selection
• Antenna subsystem
• Ground segment
• Designing for space
• Conclusions

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Delfi-C3 Mission
Delfi-C3 mission COMMS design Conclusion

• Educational objectives
• Hands-on engineering experience
• Teamwork and communication skills
• Motivate and challenge students
• Technical objectives
• In-orbit test of
• Thin Film Solar Cells
• Autonomous Wireless Sun Sensor
• Advanced Transceiver

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Points of departure
Delfi-C3 mission COMMS design Conclusion

• Telemetry data budget requires about 800 bit/s
• Power budget 2-4 W available total array power
• No active attitude control ? tumble
• Use of amateur radio frequency bands, protocols
  and modulation schemes
• Distributed ground station network
• Advanced transceiver payload
• FCC / ITU uplink requirement

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Frequency selection
Delfi-C3 mission COMMS design Conclusion

• 145.8-146 MHz (VHF) downlink
• 435-438 MHz (UHF) uplink
• VHF downlink, easy ? outreach
• No VHF uplink interference
• Compatible with AO-40 uplink equipment
• 3rd harmonic self-interference

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Space segment
Delfi-C3 mission COMMS design Conclusion

• Advanced transceiver
• AMSAT platform
• 1200 Baud AX.25 BPSK telemetry and telecommand
• Low power 500mW 40KHz mode UV linear transponder

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Advanced transceiver
Delfi-C3 mission COMMS design Conclusion

• Focus on high efficiency miniaturized linear PA
• Double loop negative feedback technique
• Prequalification for MISAT mission

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AMSAT platform
Delfi-C3 mission COMMS design Conclusion

• Telecommand, telemetry and linear transponder
  functionality
• Proven concept
• Using standard off the shelf components

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Antenna subsystem
Delfi-C3 mission COMMS design Conclusion

• VHF and UHF Quarter wave whips
• Matching network
• Near-omnidirectional pattern is desirable
• Phasing harness to provide circular polarization
• Deployment issues

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Ground segment
Delfi-C3 mission COMMS design Conclusion

• Distributed ground station network
• Telemetry software will be made available to
  participating amateurs
• Data collection over the Internet
• Required equipment
• VHF / UHF SSB transceiver
• Tracking yagis
• TNC
• Telemetry software
• DELFI command ground station

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Designing for space
Delfi-C3 mission COMMS design Conclusion

• Receiver dynamic range
• EMC ESD
• Radiation effects
• Structural loads
• Thermal vacuum
• Thorough testing

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Conclusion
Delfi-C3 mission COMMS design Conclusion

• Dutch amateur radio operators are getting
  involved
• AMSAT platform Advanced transceiver PA design
  has started
• First CubeSat flying a linear transponder
• First Dutch OSCAR

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Questions?
Delfi-C3 mission COMMS design Conclusion
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RF frontend
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MiSat
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Delfi command groundstation

• Tracking VHF/UHF antenna system at 85m ASL
• Tracking S-band antenna system
• S-band to VHF downconverter
• ICOM IC-910 transceiver under computer control
• NOVA Tracking software

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Interference canceling frontend
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Quadrature oscillator
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Advanced transceiver

• PA with integrated transformer

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Advanced transceiver
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Silicon-on-glass technology
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Linear transponder concept

• Proven amateur satellite concept
• Combined with telemetry and telecommand
• Conflicting PA linearity requirement
• No eclipse operations (like AO-7)
• Ranging / Doppler tracking possible
• Nice test case for advanced transceiver

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Designing for space

• Incorporate redundancy contingency options
• 2 uplink receivers on at all times
• ESD protection