The TTC (Telemmetry, Tracking and Command) is the subsystem in charge of giving communication capabilities to the satellite.
This subsystem receives commands from the ground station to control the satellite and also transmits satellite information to the ground station.
Its Radiofrequency emissions are located in the UHF amateur radio band at 437,325 MHz using a MSK modulation at 1200 bps. It also trasmits a CW beacon to locate the satellite in the early phases of the mission and in case of contingency.
It is remarkable the fact that this board was modified specifically for Humsat-D in order to meet the mission requirements.