The MDHU (Mission Data Handling Unit) in the MDHS (Mission Data Handling Subsystem) is primarily responsible for processing and storing mission data, and transmitting the data to the ground via the S-band. Although this subsystem is classified under the payload category, it can also be regarded as part of the platform subsystems. Its design goal is to realize the processing of images or mission data and their transmission to the ground.
The MDHU supports an S-band data link with a maximum rate of 1Mbps and can collect data through interfaces such as I2C, SPI, CAN, serial, and ADC, making it suitable for various mission scenarios. Since mission data and satellite housekeeping data are processed separately, the electrical connections and data processing volume between the platform and the payload are significantly reduced, which helps shorten the development cycle of related hardware and interfaces.
The CS (Communication Subsystem) enables remote command transmission, reception, and data transfer between the satellite and the ground station through wireless communication.
The standard platform supports two communication frequency bands: VHF and UHF, with the AX.25 communication protocol adopted. Among them, the VHF band is used to receive remote commands sent by the ground station; the UHF band is used to send beacon signals and telemetry data containing satellite status information to the ground station. The functional diagram of the CS and MDHS (Mission Data Handling Subsystem) is shown in the figure below.
Functional Diagram of CS and MDHS.
