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System Design Dave Curtis UCB/SSL Space Sciences Laboratory University of California, Berkeley

System Design Dave Curtis UCB/SSL Space Sciences Laboratory University of California, Berkeley. System Design Agenda. AGENDA Requirements Electrical System Overview Resource Summary Issues. Requirements. System Requirements have been documented in CINEMA_Requirements

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System Design Dave Curtis UCB/SSL Space Sciences Laboratory University of California, Berkeley

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  1. System Design • Dave Curtis • UCB/SSL • Space Sciences Laboratory • University of California, Berkeley

  2. System Design Agenda • AGENDA Requirements Electrical System Overview Resource Summary Issues

  3. Requirements • System Requirements have been documented in CINEMA_Requirements • Subsystem designers should be familiar with requirements placed on their system and design/test to verify compliance • Deviations from requirements need to be approved by me. • More detailed requirements have been developed in some cases • For example, Flight Software requirements, CINEMA_FSW_002_Requirements

  4. Requirements Verification • For each requirement we need to identify how/when we are going to verify it • Subsystem designers need to propose verification plans for each of their requirements to me before starting tests • Requirements verification for each subsystem shall be reviewed prior to integration • Requirements which can only be verified at a lower level of assembly need to be completed prior to integration • Some requirements need to be verified or re-verified at the system level – plans for these need to be identified prior to integration • Some requirements may have to be verified wholly or partially by analysis • test preferred • A document describing the analysis is desirable • All requirements shall be verified prior to launch

  5. Interface Control Documents • By CDR some form of ICD should exist between all subsystems which interface together • Some ICD are more formal than others • Existing ICDs • CubeSat Design Specification • Purchased hardware manuals such as EPS Users Manual • MAGIC ICD • Spacecraft Mechanical Layout & Accomodations Model • Avionics backplane Specification • Harnessing Diagram • Needs connector definitions, pinouts • FPGA Specifications (preliminary)

  6. Electrical Systems Block Diagram

  7. Mechanical Layout [Obsolete]

  8. Harnessing Diagram

  9. Resources - Mass • Somewhat Obsolete [10/09] • +UHF Antennas, deployment system • +UHF Electronics • -MicroHard Antennas • -MicroHard Electronics • LVPS/Instrument Interface combined into IIB • Updates • Plenty of Margin • 4kg limit per rev 12 CDS

  10. Resources – Power Generation • 3.22W Orbit Average, Nominal Attitude • 2.14W Worst Case Attitude

  11. Resources – Battery Capacity • 26% Max DOD (once/day, mostly S-band Transmitter) • Assumes no UHF Downlink (or only 1 transmitter on at a time)

  12. Resources – Power Usage • 80% Margin, SAFE Mode • 25% Margin, ACS, Normal Modes

  13. Resources – Telemetry • 9700bps average science (and stored engineering) rate • 9600 baud real time engineering via UHF • 27bps average engineering rate if stored engineering downlinked via UHF 1 pass/day

  14. Issues • Some ICDs/Specifications need work by subsystem designers • Subsystem designers need to start thinking about Verification Plans • Need Mass update • Need more analysis if we plan to use UHF transmitter • Can we simultaneously use S-band (needs power analysis) • We need a switch or PIN-D diode • Requires simplex operation – software & MOC complications • Need GSE (Another UHF card & antennas?) • Ground station receiver/antenna • Link margin

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