Communication System

The ION-F formation of satellites must share a high degree of commonality in the area of communications. This is required due to the inherently high degree of coordination needed for the formation flying mission, the science mission, and the use of common ground stations. To achieve this high level of compatibility among the satellites, the ION-F team designed identical communication systems wherever possible, including the use of common hardware

The Dawgstar communications system must accommodate the downlink of telemetry data, and the uplink of commands from ground control. Additionally, the ION-F formation must communicate with each other through crosslinks.

The Dawgstar communication system design consists of the following hardware components:

  • uplink receiver
  • downlink transmitter
  • crosslink transmitter
  • crosslink receiver
  • antennas for uplink, downlink, and crosslink
  • other components (wiring, splitter, diplexer)

The most important function of the on-board communication system is to transmit telemetry to the ground via the downlink. The flow of data through the telemetry system begins with the data acquisition system (DAS). DAS input can include temperature, pressure, force, position, and acceleration; the output is a single digitized data stream. The measurement device performs the function of digitizing the analog data from multiple channels into a single data stream. The data are then formatted for either storing within the flight computer memory, or transmitting directly to ground station(s).

The command system sends commands from the ground station to the satellite through the communication systemís uplink. The purpose of commands fall into two broad categories: commands make small changes to the satellite configuration, or they correct anomalies. Commands may also be used to reset clocks, execute spacecraft maneuvers, or recalibrate instrumentation, among other applications.

Hardware for the intersatellite crosslink communication system has not yet been determined. It is under development by the Applied Physics Laboratory (APL), and will be made available to the ION-F flight through the Cross-Enterprise Development Program, sponsored by NASA Goddard Space Flight Center (GSFC). A secondary purpose of the crosslink is to retransmit tones for calculation of the relative distance between satellites to provide an aid to navigation.