This document provides an overview of the major systems that the communications subteam is working on. It includes an walkthrough of the hardware designs and software designs, and contains explanations for design decisions.
The main projects discussed in this document are the Ground Station, the ARO Requests App, the ARO Uplink App, and the Onboard Custom Transceiver. This document also describes the Comms CONOPS and Operational Modes.
<aside> 💡 Some of the terms and concepts used in this document may require the reader to refer to the Comms Wiki.
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Comms CONOPS/Operational Modes
The overall operations for the Comms team includes three primary modes.
Startup mode includes a competition and CubeSat standard mandated radio silence, after which any antenna deployment occurs and an always receive mode is turned on to be able to detect the ground station. Once a link has been established, mission mode is activated.
Mission mode contains three states: idle, MCC communication, and ARO communication. On-orbit location determination is performed by ADCS. Whenever the CubeSat is about to approach either an ARO or MCC, receive mode is activated until a ping from the ground station (or Selfie-Sat pass from the ARO) is received. After reception, transmit mode is activated. For MCC passes, the CubeSat begins to transmit as much telemetry data as it can. Once all telemetry has been dumped, TLE and command data is received from the ground station. For ARO communication, once the Selfie-Sat pass has been received, the CubeSat takes a picture and immediately begins downlinking the image taken.
Emergency modes are activated whenever a link has not been established with the ground station in the past 48 hours. After this time period, decryption and error correction become disabled until contact can be achieved again. In the case of an emergency where EPS is producing low amounts of power at the same time, the receiver is periodically turned on at 2 times the shortest ground station window period. If no low power emergency is active, random beacon transmits are sent at the same frequency.
One of the communications team’s largest projects is the development of an in-house onboard transceiver.