The communication subsystem handles all communication with USUSat II. As currently designed, there are two completely autonomous communications systems working in parallel.
The communication sub-system for the TOROID mission currently follows the same design used for USUSat II. There are two links used, a command and control link and a data downlink. The command and control link operates at 450 MHz, using a USU designed and built Terminal Node Controller. This TNC uses AX.25 v 2.0, and currently we are working on a radiation hardened TNC for future use. The data downlink operates at 2.26 GHz, using an L-3 Communications ST-802S transmitter.
The command and control link is connected directly to the C&DH system through a serial link. This data is first packetized and then transmitted at 450 MHz over an array of deployed monopole antennas. Future development includes patch antennas for this system. The data downlink recives data from the telemetry board, which has placed data in a PCM matrix. The L-3 ST-802S then streams this data to the ground station, where it is de-commutated and analyized.
USUSat’s communications system can transfer data at 9.6 kbps on the command and control link, and greater than 115.2 kbps on the data downlink. With simple modifications, the same system can be modified to transmit greater than 500 kbps from LEO.