Research And Realization Of An S-Band Relay Terminal Transceiver Channel

Due to the limitation of the production cycle and quantity,the traditional relay satellites have been unable to meet the growing demand for data transmission services and customer groups.Through the understanding and analysis on the status of domestic and foreign relay satellites,the development trend of relay satellite systems in the future is to realize the air-ground integrated data transmission network through micro satellites and satellite constellation networks.This puts high demands on the on-board equipment of future relay satellites: it must meet the functional requirements of user data transmission,measurement and control tracking,and platform restrictions of the microsatellites.Based on the actual needs of the work,this thesis proposes a designing scheme for a miniaturized,lightweight,low-power S-band Relay terminal transceiver channel.Firstly,the current research and design status of the current S-band relay terminal in China,the working principle and main functions are given.By analyzing the advantages and disadvantages of typical structures of receivers and transmitters currently used,the specific implementation schemes of the receiving channel part and the transmitting channel part are determined.In order to realize the design requirements of the S-band relay transceiver channel,the receiving channel module and the transmitting channel module adopt the whole board design idea.To reduce the number and size of independent boards,the components are dominated by domestic integrated modules,which reduc the proportion of traditional discrete devices.The receiving channel module selects the superheterodyne receiver scheme for design.After going through the low-noise,second-down,two-mixed,Automatic Gain Control(AGC),two-distribution circuits,the receiving channel module converts the uplink signal into the low IF signal.The low IF signal is sent to the digital processing module.The transmit channel module selects a multi-step transform scheme for the circuit design.After being processed by the digital processing module,the spread spectrum signal including the telemetry information and the ranging information.The spread spectrum signal after being modulated,combined,amplified,and filtered by a modulator in the transmit channel module,become to a downlink signal.After the module is produced,assembled and debugged,the final test results meet the design index requirements proposed at the beginning of the thesis: The remote control demodulation threshold is less than-110 dBm,and the receiving dynamic range is better than 40 dB.In the future,the S-band transceiver channel designed by the scheme can be used in relay satellite systems or other S-band measurement and control systems.