Some notes from research:

Physical Interface:

  • RS-422 / UART -> default for commercial satellites 
    • Typical Baud Rate: 115.2 kbps
    • Effective useful data rate: 80-100 kbps
  • CAN Bus
  • Depending on how much data is generated or sent 
    • Ethernet or Spacewire (high data rate) 

-> maybe two channels? One for telemetry, health and commands (RS-422) and one for science data (ethernet)

Some data stuff:

  • Throughput data
    • Max sustained 
  • Packet format
  • Connector types and pinouts
  • Onboard time synchronization 

Expected telemetry:

  • Physical health and status of payload
  • Payload mode
  • Voltages and current
  • Temperatures 
  • Internal clocks + timing
  • Science data


General Satellites

Commanding Set

  • The complete collection of commands that the ground system can send to a spacecraft(what actions the satellite can perform in response to operator instructions)
  • Subsystem commands
    • ADCS
    • Power
    • Thermal
    • Communications
    • Payload
  • Command Types
    • Real-time
    • Stored time-tagged commands
    • Macrocodes/procedures
    • Parameter uploads
  • Command Structure
    • Opcode
    • Subsystem address
    • Parameter
    • Authentication


Data Exchange Architecture

  • How data flows between ground and spacecraft, and within spacecraft
  • Uplink Architecture (Command path)
    • Mission Control - Ground Station Network
    • Ground station - RF uplink - satellite
    • Communication Subsystem - OBC
    • Flight software - subsystem interfaces
    • (Link budget, modulation, coding, encryption, authentication)
  • Downlink Architecture
    • Real-time telemetry
    • Stored telemetry
    • Mission/payload data
    • Health/status messages
    • Event logs + fault reports
    • (Data rates, channelization, coding, packetization)
  • Onboard Data Handling Architecture
    • OBC
    • Data buses
    • Redundancy management
    • Payload data processor
    • Mass memory
    • (routing commands, collect telemetry, synchronization, FDIR)
  • Ground Segment Data Flow
    • Command generation and validation
    • Telemetry processing and monitoring
    • Archive and distribution
    • Automation

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