May 2022, Volume 5 Issue 2

    

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• Development and Future of China’s Deep Space TT&C System

  DONG Guangliang, LI Haitao, HAO Wanhong, WANG Hong, ZHU Zhiyong, SHI Shanbin, FAN Min, ZHOU Huan, XU Dezhen

  2018, 5(2): 99-114. https://doi.org/10.15982/j.issn.2095-7777.2018.02.001

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  With the implement of China’s Lunar Exploration Program in three stages，which consist of orbiting，landing，and returning， China’s deep space TT&C（Tracking，Telemetry and Command）system has been built up. The future Mars Exploration Program will further enhance the full capability of the system. In this paper, the development of China’s deep space TT&C system is reviewed，including the details of key technology research，top design，and system construction. The future trend of this system is discussed based on the latest development of deep space TT&C technologies.
• Improvement of BepiColombo’s Radio Science Experiment Through an Innovative Doppler Noise Reduction Technique

  M J MARIANI, A DI RUSCIO, V NOTARO, L IESS

  2018, 5(2): 115-123. https://doi.org/10.15982/j.issn.2095-7777.2018.02.002

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  The Mercury Orbiter Radio science Experiment (MORE), onboard the ESA/JAXA BepiColombo mission to Mercury, is designed to estimate Mercury’s gravity field, its rotational state, and to perform tests of relativistic gravity. The state-of-the-art onboard and ground instrumentations involved in the MORE experiment will enable to establish simultaneous X/X, X/Ka and Ka/Ka-band links, providing a range rate accuracy of 3 μm/s (at 1 000 s integration time) and a range accuracy of 20 cm. The purpose of this work is to show the improvement achieved on MORE’s performance by means of the Time-Delay Mechanical Noise Cancellation (TDMC) technique. The TDMC consists in a combination of Doppler measurements collected (at different times) at the two-way antenna and at an additional, smaller and stiffer, receive-only antenna located in a site with favorable tropospheric conditions. This configuration could reduce the leading noises in a Ka-band two-way link, such as those caused by troposphere and ground antenna mechanical vibrations. The results of end-to-end simulations and estimation of Mercury’s gravity field and rotational state considering the TDMC technique are presented. The results for a two-way link from NASA’s DSS-25 (in Goldstone, CA) or from ESA’s DSA-3 (in Malargue, Argentina) are compared, while the APEX is assumed as the receive-only antenna. It shows that in best-case noise conditions, the TDMC technique allows to obtain a factor-of-two accuracy gain on both global and local parameters, considering DSA-3 as a two-way antenna. Such improvement in the scientific objectives of MORE is of geophysical interest as it could provide a constraint on the interior structure of Mercury.
• Research on Space Time Delay Compensation Method Based on Beam Squint Technique

  DUAN Yuhu

  2018, 5(2): 124-128. https://doi.org/10.15982/j.issn.2095-7777.2018.02.003

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  In deep space TT&C mission，the space time delay and Earth rotation make the narrow beam of large ground antennas unable to cover the corresponding orbit area，which leads to the quality deterioration or even interruption of the communication link. A technique for a real-time beam separation correction scheme for deep space uplink and downlink communications is presented，which provides a close relationship between the beam squint angles and the corresponding feed displacement for a reflector antenna with a beam waveguide（BWG）or multiple reflector system. The simulation results of 35-meter antenna at Ka band（34 GHz）show that the uplink beam gain loss is less than 4.25 dB by moving the uplink feed position when the up/downlink beam separation angle is 0.032 72 °. It is also useful to determine the feed offset position to correct the beam deviation caused by the imperfect antenna mechanical structure and the mirror misalignments of the complex multiple reflector system.
• Space Communication and BATS Codes: A Marriage Made in Heaven

  YEUNG Raymond W., Guangliang DONG, Jian ZHU, Haitao LI, Shenghao YANG, Chao CHEN

  2018, 5(2): 129-139. https://doi.org/10.15982/j.issn.2095-7777.2018.02.004

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  Innovative communication technologies are in great demand in the national space development program. In this paper, space communication with network coding is studied, with the aim of exploring the feasibility and potential of network coding for future space communication. The characteristics of space communication are first discussed, and an overview of different coding based methods is given. As a potentially applicable technology, network coding based Batched Sparse (BATS) code is presented to address the packet loss problem in multi-hop relay networks. In particular, a BATS code prototype is designed and implemented, and the experiment results demonstrate the advantages of BATS codes over alternative technologies. Finally, the prospect of deployment of BATS codes in space communication is discussed.
• Development of Deep Space Radio Ranging and Velocity Measurement Technology

  XU Maoge, SHI Weihua

  2018, 5(2): 140-146. https://doi.org/10.15982/j.issn.2095-7777.2018.02.005

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  The recent research progress of the deep space radio ranging and velocity measurement technology, including the ESA and NASA measurement accuracy improvement plan is introduced. Based on the X frequency band experimental data，using the extreme narrow phase-locked loop（PLL）and the 500 kHz ranging tone，the current situation of ranging and velocity measurement of China's deep space tracking，telemetry and command（TT&C）system is analyzed. The main error budget is analyzed and the accuracy improvement suggestions are provided. According to the deep space exploration program，the proposal of deep space measurement technology is presented，particularly the analyses of multi-frequency link scheme and the station delay bias online monitoring are given.
• Study on Integrated Technique of Laser Ranging and Communication and Its Applications in Deep Space

  LIU Xiangnan, LI Yingfei, XIANG Chengyong, CHEN Ming, LI Xiaoliang

  2018, 5(2): 147-153. https://doi.org/10.15982/j.issn.2095-7777.2018.02.006

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  The current development of integrated technique of laser ranging and communication is introduced. A new integrated technique of high precision laser ranging and high speed communication is presented based on dual one-way ranging（DOWR）and BPSK modulation heterodyne coherent detection. A symbol phase ranging method is applied to achieve the integrated system design，and the ground experiments are developed. The results show that the data rate of laser link reaches 1 Gbit/s and the ranging precision is better than 0.9 mm. The influence of reference clock frequency difference on ranging precision is analyzed. Finally，future applications of the integrated laser ranging and communication system in deep space exploration are expected.
• Preliminary Numerical Analysis of Precise Orbit Determination for a Multi-Way Microwave Measurement Mode in the Lunar and Mars Missions

  YANG Xuan, YAN Jianguo, YE Mao, JIN Weitong, QU Chunkai, LIU Suyan

  2018, 5(2): 154-161. https://doi.org/10.15982/j.issn.2095-7777.2018.02.007

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  Precise orbit determination and lander positioning have important scientific meaning in deep-space mission. In this paper，preliminary numerical simulations for a multi-way microwave measurement mode in the Lunar and Mars missions are conducted and analyzed. The measurement model of this tracking mode is derived and its advantages are evaluated. Simulation results show that this model has the potential to improve orbit accuracy，and the position of the lander can also be obtained. The quantitative analysis shows that at the noise level of 1 mm/s，for the Lunar spacecraft，the orbit accuracy can be up to several meters and the positioning accuracy of the lander is expected to reach the decimeter level，considering the coordinate system conversion error，the gravitational field error，the ephemeris error and the transponder error. For the Mars spacecraft，the orbit accuracy can reach tens of meters and the lander positioning accuracy reaches the meter level.
• A Deep Space Exploration Carrier Capture Algorithm with Low SNR

  DU Jianlai, FANG Kun, LIU Gang, LI Qi

  2018, 5(2): 162-167. https://doi.org/10.15982/j.issn.2095-7777.2018.02.008

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  Aimed at the extremely low Signal-Noise-Ratio（SNR）of the carrier signal received by receiving end in the deep space monitoring and control communication system，a two-dimensional time division multiplexing fast Fourier transform（FFT）carrier acquisition method is proposed. The carrier capture can be achieved effectively at low SNR while reducing resource consumption. Simulation results show that this method can be used to achieve fast acquisition of a carrier signal with carrier frequency offset up to 100 kHz and carrier frequency change rate up to 100 Hz/s under the carrier-noise-ratio（CNR）of 17 dBHz. It is a capture method that takes both performance and engineering into account.
• Optimal Design for Distributed Antenna Arraying System

  ZHAN Yafeng, DUAN Chaowei, KONG Qian

  2018, 5(2): 168-174. https://doi.org/10.15982/j.issn.2095-7777.2018.02.009

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  In a distributed antenna arraying system, an effective large aperture with low cost can be realized by utilizing the existing antenna resources. For the receiving signal-to-noise ratios（SNRs）of antennas with different apertures in distributed antenna arraying system vary in a large range，a question is raised that is the combined performance improved with arbitrary antennas added into the distributed antenna arraying system? An optimal design criterion is proposed to solve this issue. Based on the estimation algorithm’s performance and the Cramer-Rao bounds （CRBs）of carrier frequency, delay and carrier phase, the criterion proves. that the combined BER performance is degraded when antennas with receiving signal’s SNR lower than the outlier effect threshold of carrier frequency estimation are added to the distributed antenna arraying system. Theoretical analysis and simulation results verify the above conclusion.
• A design of 50 kW X-Band High Power Amplifer

  LI Xinsheng, LIU Haixu, HAN Laihui, HOU Manhong, WEN Chaoju

  2018, 5(2): 175-181. https://doi.org/10.15982/j.issn.2095-7777.2018.02.010

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  Based on the needs of development to deep space exploration and other space measure and control communication，a X-band continuous wave（CW）high power amplifier（HPA）based on the klystron scheme is presented，in which the high efficient low ripple modularized switch power，centralized liquid cooling equipment， high power filters and high speed reliable control measures are adopted，and the function of CW high power output in X-band deep space exploration is realized. The test results show that the CW output power can reach 50 kW（even up to 60 kW），the second，third and fourth harmonics are good and the cooling effect is ideal in the required bands. In addition，it shows that after long-time working the specifications of the equipment and working state are very steady and reliable which will provide supports for the further development of deep space exploration.
• Experimental Research of Phase-Stabilized Transfer of RF Signal over Optical Fiber

  LIU Youyong, MA Wenqi, CHEN Shaoqing, LI Jing

  2018, 5(2): 182-187. https://doi.org/10.15982/j.issn.2095-7777.2018.02.011

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  A method of phase-stabilized transfer of RF signal over optical fiber is proposed in order to meet the urgent needs of high stability RF signals in uplink arrays. Phase jitter of signal transfer over optical fiber is detected and compensated by transmitting a tone signal bidirectionally in the closed loop transmission system based on optical delay line. The principal and methods of the experiment are explained in detail and an experimental system is designed. Preliminary results show that the phase jitter of the RF signal after transmission is within 1° when a temperature change of 40 ℃ occurs over an 1 km optical fiber. The phase jitter of the optical fiber transmission system can be compensated effectively which satisfies the needs of high stability RF signals in uplink arrays.
• Development of Variable-Emittance Thermal Control Technology

  JIN Haibo, LING Chen, LI Jingbo

  2018, 5(2): 188-200. https://doi.org/10.15982/j.issn.2095-7777.2018.02.012

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  Small and micro-satellites are playing more and more important role in current and future space missions. Small spacecraft provide limited space and weight for thermal control system. As an important thermal control technology of spacecraft，the variable emittance devices is of great significance for reducing the load and volume of spacecraft as well as adapting to wide temperature swing in space. Thermochromic smart variable emittance devices can meet the loading requirement of small spacecraft and realize efficient thermal control. The basic principles and progress of both active and passive emittance thermal control devices are summarized. In which，the vanadium dioxide based thermochromic variable emittance thermal control device is introduced in detail. The basic principle，preparation methods and research progress are presented，and the development of variable-emittance thermal control technology is prospected.