314
9 OBDH Technology of Lunar Lander
could achieve a high speed transmission rate from 100 Mb/s to 1 Gb/s. In addition,
the low voltage swing could reduce power consumption and have the advantage
of differential transmission. LVDS was used in simple circuit drivers and receiver
physical layer devices as well as complex interface communication chipsets. These
chipsets could significantly save the cost of the system’s cable and connectors, and
reduce the physical space required for the connector’s footprint. Because it could
make the power supply voltage of the system low to 2 V, LVDS could enable mw/GB
solutions for present and future high-bandwidth data transmission applications, so it
was very suitable for the need of high speed and low consumption in the future deep
space exploration. Up to date, LVDS interface had been widely used as a high-speed
data transmission channel on spacecraft. LVDS interface had been widely used in
high speed payload (such as camera, sensor), large capacity memory, multiplexer
and data transmission devices.
The high speed image data flow on the lunar lander, such as the landing camera,
the surveillance camera, the topographic and geomorphic camera, was only stored,
and was not transmitted in real time. So it could be transmitted to the SMU after
being multiplexed and stored through LVDS high-speed data interface.
9.4.5 Information Management Design
Through the uplink and downlink channels, the OBDH subsystem connected the
platform data and the T&T information of the ground station, and made up a closed
loop system to realize the operation management and maintenance of spacecraft on
orbit, such as orbital test, the management and maintenance including monitoring and
control of operational status, the diagnosis and elimination of faults, the switching
control and reconfiguration of subsystems and components, and the modification
and updating of flight software. The data flow of the integrated electronic system in
spacecraft is shown in Fig. 9.3.
1. Platform Data Flow
The platform data flow included telemetry data and navigation/positioning data.
(1) Telemetry data: telemetry data collected by remote terminals or other subsystems are transmitted to CTU through SDB to form a telemetry transmission
frame, and the telemetry video signals and telemetry PCM data were sent to
the TT&C transponder, from which the data would be sent to ground station or
relay spacecraft through the TT&C channel. In addition, the telemetry transmission frames were transmitted to Data Multiplexer Unit when the spacecraft
could be accessed by ground station, and are delivered via the data transmission channel. When the spacecraft cannot be accessed by ground station, they
are transferred to a large-capacity memory for storage.
9 OBDH Technology of Lunar Lander
could achieve a high speed transmission rate from 100 Mb/s to 1 Gb/s. In addition,
the low voltage swing could reduce power consumption and have the advantage
of differential transmission. LVDS was used in simple circuit drivers and receiver
physical layer devices as well as complex interface communication chipsets. These
chipsets could significantly save the cost of the system’s cable and connectors, and
reduce the physical space required for the connector’s footprint. Because it could
make the power supply voltage of the system low to 2 V, LVDS could enable mw/GB
solutions for present and future high-bandwidth data transmission applications, so it
was very suitable for the need of high speed and low consumption in the future deep
space exploration. Up to date, LVDS interface had been widely used as a high-speed
data transmission channel on spacecraft. LVDS interface had been widely used in
high speed payload (such as camera, sensor), large capacity memory, multiplexer
and data transmission devices.
The high speed image data flow on the lunar lander, such as the landing camera,
the surveillance camera, the topographic and geomorphic camera, was only stored,
and was not transmitted in real time. So it could be transmitted to the SMU after
being multiplexed and stored through LVDS high-speed data interface.
9.4.5 Information Management Design
Through the uplink and downlink channels, the OBDH subsystem connected the
platform data and the T&T information of the ground station, and made up a closed
loop system to realize the operation management and maintenance of spacecraft on
orbit, such as orbital test, the management and maintenance including monitoring and
control of operational status, the diagnosis and elimination of faults, the switching
control and reconfiguration of subsystems and components, and the modification
and updating of flight software. The data flow of the integrated electronic system in
spacecraft is shown in Fig. 9.3.
1. Platform Data Flow
The platform data flow included telemetry data and navigation/positioning data.
(1) Telemetry data: telemetry data collected by remote terminals or other subsystems are transmitted to CTU through SDB to form a telemetry transmission
frame, and the telemetry video signals and telemetry PCM data were sent to
the TT&C transponder, from which the data would be sent to ground station or
relay spacecraft through the TT&C channel. In addition, the telemetry transmission frames were transmitted to Data Multiplexer Unit when the spacecraft
could be accessed by ground station, and are delivered via the data transmission channel. When the spacecraft cannot be accessed by ground station, they
are transferred to a large-capacity memory for storage.