Wake-up subsystem

The wake-up subsystem (WUS) is essential to initiate the power-up sequence of the YPSat upon detecting the Ariane 6 lift-off. Prior to the launch, the YPSat will be held in a state of hibernation to preserve power between the last battery charging before encapsulation and the launch. The WUS operates autonomously, featuring an accelerometer and a barometric pressure and temperature sensors, to detect the launch event by monitoring the movements of the payload.

The launch is identified after detection of significant acceleration, followed by assessments of the barometric pressure to confirm the launch event. In parallel, a secondary independent circuit serves as a backup for the wake-up. This circuit monitors the deployment signal that will be sent out by Ariane 6 when in orbit. This backup wake-up signal is passed to the On-Board-Computer and ensures a late wake-up in case of non-conformancy in the WUS. It is also used when the self-detection of the launch was successful: the mission timeline is resynced with the time of this signal to get more precision on the timings.  Once the launch is detected, the Electrical Power System is activated to initiate start-up of the YPSat.