310
9 OBDH Technology of Lunar Lander
telecommand information and frame verification. The telecommand data would be
sent to CTU, and direct on/off commands would be sent to the user after decoding.
CTU was the upper computer of the double-level distributed system. It was the
distributed and control center of spacecraft telemetry and telecommand information.
It received the telecommand data from the TCU, and distributed the data to user
directly through the DB or indirect on/off commands and serial loading instructions.
It also collected data from different remote terminals to process and store. The data
generated by the DB and / or special high speed interface and the data generated by
the CTU software could formulate the telemetry frame, format or source package.
After the channel coding and subcarrier modulation, the serial data was sent to the
downlink telemetry channel. By controlling the running state of DB, CTU could
realize the uplink data distribution and spacecraft data acquisition in time division
mode. CTU would complete integrated electronic functions of spacecraft according
to mission requirements, so the CTU must have a high data processing capacity,
enough running speed and storage space, and corresponding interface.
RTU was the interface between OBDH subsystem and user subsystems to
complete the telemetry data (including analog, temperature, double level, and serial
digital) acquisition, indirect on/off commands, serial loading commands and data
distribution.
DMU received the telemetry source package and the remote sensor data bit stream.
The unified organization and management of the data flow of the spacecraft could be
realized by using the CCSDS standards. The platform data and the payload business
data were combined for transmission through the digital physical channel.
DDR provided the storage medium for platform data and payload business data.
The payload business data and the platform data were recorded in the digital data
recorder in real time through the DMU, and were read from DMU when the spacecraft
was accessed by ground station or relay spacecraft, and then transmitted through
DMU to the telecommunication system.
All kinds of intelligent remote terminals were connected to the DB, and responded
to CTU only when their addresses were in accordance with the addresses specified
in the CTU command. DB was the only channel connecting CTU with all remote
terminals, and the operation of DB was controlled by CTU.
9.4.3 Miniaturized and Integrated System Design
Lightweight and miniaturization had always been the focus of spacecraft electronic
system design. The issue was particularly prominent in lunar soft-landing missions.
One of the effective ways to solve this issue was to integrate electronic systems.
Targeting at the mission requirements of lunar soft-landing mission, based on the
intelligent modularization, the data information flow was optimized and the resource
allocation was integrated. The integrated and optimized design of electronic devices
was conducted with the guarantee of reliability, including the function integration of
devices, the selection of components and the shell material, the design of housing,
9 OBDH Technology of Lunar Lander
telecommand information and frame verification. The telecommand data would be
sent to CTU, and direct on/off commands would be sent to the user after decoding.
CTU was the upper computer of the double-level distributed system. It was the
distributed and control center of spacecraft telemetry and telecommand information.
It received the telecommand data from the TCU, and distributed the data to user
directly through the DB or indirect on/off commands and serial loading instructions.
It also collected data from different remote terminals to process and store. The data
generated by the DB and / or special high speed interface and the data generated by
the CTU software could formulate the telemetry frame, format or source package.
After the channel coding and subcarrier modulation, the serial data was sent to the
downlink telemetry channel. By controlling the running state of DB, CTU could
realize the uplink data distribution and spacecraft data acquisition in time division
mode. CTU would complete integrated electronic functions of spacecraft according
to mission requirements, so the CTU must have a high data processing capacity,
enough running speed and storage space, and corresponding interface.
RTU was the interface between OBDH subsystem and user subsystems to
complete the telemetry data (including analog, temperature, double level, and serial
digital) acquisition, indirect on/off commands, serial loading commands and data
distribution.
DMU received the telemetry source package and the remote sensor data bit stream.
The unified organization and management of the data flow of the spacecraft could be
realized by using the CCSDS standards. The platform data and the payload business
data were combined for transmission through the digital physical channel.
DDR provided the storage medium for platform data and payload business data.
The payload business data and the platform data were recorded in the digital data
recorder in real time through the DMU, and were read from DMU when the spacecraft
was accessed by ground station or relay spacecraft, and then transmitted through
DMU to the telecommunication system.
All kinds of intelligent remote terminals were connected to the DB, and responded
to CTU only when their addresses were in accordance with the addresses specified
in the CTU command. DB was the only channel connecting CTU with all remote
terminals, and the operation of DB was controlled by CTU.
9.4.3 Miniaturized and Integrated System Design
Lightweight and miniaturization had always been the focus of spacecraft electronic
system design. The issue was particularly prominent in lunar soft-landing missions.
One of the effective ways to solve this issue was to integrate electronic systems.
Targeting at the mission requirements of lunar soft-landing mission, based on the
intelligent modularization, the data information flow was optimized and the resource
allocation was integrated. The integrated and optimized design of electronic devices
was conducted with the guarantee of reliability, including the function integration of
devices, the selection of components and the shell material, the design of housing,