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OSSI Command & Data Handling System

Work principle of the spacecraft

  1. TC/TM on 30 mins after ejected from FlyMate
  2. Telemetry Beacon emits continously
  3. Downlink Data emits only when there is accepted Uplink Data from earth
  4. CDHS Specification

block Diagram

Data Parts

Beacon Parts

Beacon Requirement

In the case of data Tx is not working, beacon should work.

  1. direct power supply from the battery - > PA should be stable for wide supply range
  2. very low power consumption → so the beacon can operate at all time
  3. PA power can be adjusted from 100mW to 1W

Antenna Panel Parts

1. TX (Data + Beacon)

- Data:

  • 430MHz Amateur (435MHz ~ 438MHz)
  • Halfwave Dipole Antenna made from measuring tape (Data TX and Data TX share the antenna by RF switch)
  • Power: 2W Max Power
  • AX.25 Protocol
  • 2-FSK Modulation
  • 1200 Bps (9600 Bps)
  • BW: 25kHz

- Beacon:

  • 144MHz Amateur
  • 1/4 Wavelength Monopole Antenna made from measuring tape
  • Power: 80m~1W Power
  • CW or 4-FSK
  • QRSS experimentation (OPERA or WSPR(4-FSK))

Beacon Detail

2. RX

  • 430MHz Amateur (435MHz ~438MHz)
  • Halfwave Dipole Antenna made from measuring tape (Data TX and Data TX share the antenna by RF switch)
  • AX.25 Protocol
  • 2-FSK Modulation
  • 1200 Bps (9600 Bps)

Type of information received from the spacecraft

  • Telemetry Beacon: Satellite monitoring information ( Voltages of Battery, Solar Cell / Temp. of Battery, Outer/inner panel and etc)
  • Downlink: Random number from 1 ~ 100 / seed number based on Cosmic Microwave Background radiation in UHF Band
subsystems/comms.txt · Last modified: 2012/12/16 13:31 by ossi