What Is The Function Of Telemetry And Control Subsystems?

Telemetry and control subsystem provide a way for the ground station to manage the satellite. The communication channels used for this function are entirely separate from the communication  channels used to relay user message  from uplink to downlink (Which  is the satellite's Primary  purpose) Via  status  telemetry , the satellite transmits in formation back to the ground  station  about hundreds of vital internal voltages , currents  temperature, and fuel level, as well as positional and orientation  information . This information is used to monitor "health" and operation continuously, indicating both sudden failures  and signs of potential problems (such as Temperature too high in a high power downlink amplifier).

Because the telemetry and control subsystem  is so critical  to ensuring  that he satellite achieves orbit  and maintains  and corrects orbital position ( Called station shipping) as well as for monitoring the performance and even fixing  the satellite, the telemetry plus  control electronics are as separate as possible  from the communication electronics. The telemetry and control subsystem has it own battery, power converter, up link, down link and even antenna system.

Any failure in the communications subcircuitry does not effect the telemetry and control circuitry, which is needed to reconfigure the rest of the satellite when problems occur.