We received a shipment of microSD socket breakout boards and fitting storage cards (along with some other development supplies) today and started development of our telemetry storage system.
During the flight, the FFU is going to log all gathered telemetry from the pFDAs along with some general housekeeping data like temperature sensor readings redundantly to two micro SD cards. After the recovery of the FFU, we are going to dump the contents of the SD cards to files and extract the stored telemetry packets. The redundancy will help us in case one of the SD cards gets damaged or experiences data corruption during flight or recovery.
This system is adapted from the temporary telemetry storage system of the TechnoSat nanosatellite which was also developed and is currently operated by the TU Berlin. The main differences between our system and TechnoSat’s are the storage medium (TechnoSat uses a NAND Flash chip instead of SD cards) and that TechnoSat does not require redundancy since the system is just used for temporary buffer of telemetry while the satelite does not have a connection to the ground station.