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University of Maryland DYMAFLEX SHOT II Pre-Flight Presentation

University of Maryland DYMAFLEX SHOT II Pre-Flight Presentation. June 29, 2012. Mission Overview. Test of DYMAFLEX low rate communications system Verify link margins on a balloon flight Verify packet reception with a similar link margin

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University of Maryland DYMAFLEX SHOT II Pre-Flight Presentation

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  1. University of MarylandDYMAFLEXSHOT II Pre-Flight Presentation June 29, 2012

  2. Mission Overview • Test of DYMAFLEX low rate communications system • Verify link margins on a balloon flight • Verify packet reception with a similar link margin • Determine actual packet loss percentage with satellite link margin • Verify custom packet checking scheme • Validate preliminary satellite software • Confirms theoretical link calculations for satellite in the desired orbit • Proves functional hardware for satellite use • Highlights any issues with radio hardware or C&DH

  3. DYMAFLEX Connection • Balloon flight test of satellite radios • Will help gather data to determine if these radios, which are intended for use in the satellite, are a reasonable option • Initial tests of satellite flight software • Contains same C&DH components as satellite and first revision of software intended for use on the satellite

  4. Payload Block Diagrams

  5. Payload Design: Mechanical and RF • Mechanical: • White foamcore poster board, folded with angle cuts for structural integrity • Tube attachment with washers and paper clips for holding in place • Insulating foam used to keep components in place and for thermal purposes • RF: Receiver, Transmitter, TNC, Splitter/Combiner • TNC: Kantronics KPC9612 • XCTR: Hamtronics T304 • RCVR: Hamtronics R303 • Inside shielded box internal to the main structure • 4 dipole antennas, 2 for receive, 2 for transmit • UHF: 435.15 Mhz • Balloon Payload EIRP: 0.37W • Link Margin: 7.00 dB • VHF: 145.89 Mhz • Link Margin: 8.38 dB Info.aprs.net

  6. Payload Design: C&DH • dsPIC33FJ256GP710A – the flight computer • breakout which will be used in flatsat testing • Thermister • Canbustransciever for future DYMAFLEX testing • SD card for logging received packets • 32.768kHZ crystal for accurate timekeeping

  7. Payload Design: Software • Follows same pattern as final flight computer • Three independent non-blocking processes • Groundstation handler • Sensor handler • Satellite handler • Currently lacks some satellite fail-safes • Only one interrupt driven process

  8. Test Data • Bench testing between satellite and ground station • C&DH and COMM systems integrated • No packets lost during testing • Serial functionality between COMM and C&DH has no issues • Software working as expected • Transmission tested from satellite to ground station • Uplink from ground station to satellite not yet tested • Sensors on C&DH record reasonable data: 76° F measured room temperature, packet count accurate, RTC count accurate

  9. Flight Expectations • On board logging of all data • All raw packets • All packet data (packet count, commands received, retries made) • Ground station logging of all data • All raw packets • Packets received and packet count versus the packet number in the received packet • Dropped packet percentage will play a key role in determining the viability of the radios and the robustness of the packet checking scheme • Packet information • Temperature, time C&DH has been active, current satellite mode, number of packets sent so far • Expect minimal packet loss and that the radios will be determined adequate for the satellite needs in this simulated environment testing

  10. Payload Demonstration • Demo: Satellite typical status packet • Satellite sends and logs packet • Ground station receives and logs packet successfully • View interior and exterior of payload

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