10.3 Analysis of Technical Characteristics
341
not the main telecommunication band. The specific frequency band of S/X-band
was divided into uplink band 2025~2110 MHz (S-band) and 7190~7235 MHz (Xband); downlink band 2200~2290 MHz (S-band) and 8450~8500 MHz (X-band).
The S-band telecommunication technology was developed earlier and was widely
applied, while the frequency resources were relatively limited. The application of
X-band was conducive to lightweight and miniaturization design of antennas and
other instruments. In the Chang’E-3 mission, the X frequency band was applied
for the telemetry/telecommand and telecommunication. The S-band was applied for
telemetry/telecommand near Earth and the backup channel of X-band telemetry and
telecommand channel in other phases.
3. Full Space Telemetry and Telecommand
In order to ensure stable and reliable TC/TM channel during all flight phases of the
lunar lander, the X-band telemetry and telecommand of the lunar lander should meet
full space telemetry and telecommand requirement. Generally, two half space (or
quasi half space) covered telemetry and telecommand antennas were applied in Earth
orbit spacecraft, which were installed symmetrically on spacecraft surface to achieve
quasi full space coverage. The uplink signal was received by two telemetry and
telecommand antennas, and then was combined by antenna network and other passive
devices, which would cause interference between two antenna patterns. In order
to overcome the same frequency interference phenomenon, antenna array with two
different frequency half space covering antennas was applied in the X-band telemetry
and telecommand of the Chang’E-3 lunar lander to achieve full space coverage.
Frequency point 1 channel was for half space and frequency point 2 channel was for
another half space, so as to avoid the blind area caused by interference effectively
and achieve full space telemetry/telecommand coverage in all flight phases. After
landing, the telemetry/telecommand channel to lunar surface was shut off and only
the ground channel was reserved.
10.4 Design of Telemetry/Telecommand
and Telecommunication Technology
10.4.1 Overview
During the mission, the telemetry/telecommand and telecommunication link between
the lunar lander and the ground station was established. As shown in Fig. 10.1, the
Chang’E-3 lunar lander and the lunar rover communicated directly with the ground
station, including receiving uplink telecommand, sending engineering telemetry and
payload data. the Chang’E-3 lunar lander could also cooperate with the ground
station to measure the orbit by the tracking signal (ranging and interferometric
angle measurement signal) in the uplink/downlink signal. Besides conventional
341
not the main telecommunication band. The specific frequency band of S/X-band
was divided into uplink band 2025~2110 MHz (S-band) and 7190~7235 MHz (Xband); downlink band 2200~2290 MHz (S-band) and 8450~8500 MHz (X-band).
The S-band telecommunication technology was developed earlier and was widely
applied, while the frequency resources were relatively limited. The application of
X-band was conducive to lightweight and miniaturization design of antennas and
other instruments. In the Chang’E-3 mission, the X frequency band was applied
for the telemetry/telecommand and telecommunication. The S-band was applied for
telemetry/telecommand near Earth and the backup channel of X-band telemetry and
telecommand channel in other phases.
3. Full Space Telemetry and Telecommand
In order to ensure stable and reliable TC/TM channel during all flight phases of the
lunar lander, the X-band telemetry and telecommand of the lunar lander should meet
full space telemetry and telecommand requirement. Generally, two half space (or
quasi half space) covered telemetry and telecommand antennas were applied in Earth
orbit spacecraft, which were installed symmetrically on spacecraft surface to achieve
quasi full space coverage. The uplink signal was received by two telemetry and
telecommand antennas, and then was combined by antenna network and other passive
devices, which would cause interference between two antenna patterns. In order
to overcome the same frequency interference phenomenon, antenna array with two
different frequency half space covering antennas was applied in the X-band telemetry
and telecommand of the Chang’E-3 lunar lander to achieve full space coverage.
Frequency point 1 channel was for half space and frequency point 2 channel was for
another half space, so as to avoid the blind area caused by interference effectively
and achieve full space telemetry/telecommand coverage in all flight phases. After
landing, the telemetry/telecommand channel to lunar surface was shut off and only
the ground channel was reserved.
10.4 Design of Telemetry/Telecommand
and Telecommunication Technology
10.4.1 Overview
During the mission, the telemetry/telecommand and telecommunication link between
the lunar lander and the ground station was established. As shown in Fig. 10.1, the
Chang’E-3 lunar lander and the lunar rover communicated directly with the ground
station, including receiving uplink telecommand, sending engineering telemetry and
payload data. the Chang’E-3 lunar lander could also cooperate with the ground
station to measure the orbit by the tracking signal (ranging and interferometric
angle measurement signal) in the uplink/downlink signal. Besides conventional