7.4 Design Methodology
235
Extenderlens
DSP
APD Detector 1
OpƟcal Filter
GNC
Secondary Power Unit
Laser Unit
Primary Power
Detector 1
OpƟcal Filter
Detector 3
APD Detector 4
APD Detector 3
SpliƩer
SpliƩer
-Z axis
-X axis
APD Detector 2
OpƟcal Filter
Detector 2
Thermal Control Unit
Fig. 7.4 Block diagram of Laser Rangefinder
and etc. burned in the digital processing unit. The block diagram of the Optical Image
Sensor is shown in Fig. 7.5.
8. Gamma Shutdown Sensor
The Gamma Shutdown Sensor was used to accurately measure the height of the lunar
lander from lunar surface when it was close to lunar surface, and gave the engine
shutdown signal at a specific height from lunar surface. The Gamma Shutdown
Sensor consisted of a transmitter and a receiver. The transmitter was a gamma source
and was a passive component of the subsystem. The receiver included three separate
gamma ray receiving and processing channels, and provided three altitude data along
each gamma ray as shown in Fig. 7.6.
9. Central Control Unit
The Central Control Unit was the controller of GNC subsystem. It was the information
processing center of the entire GNC subsystem. The measurement signals of all