Design Of Reconfigurable Data Transmission Transmitter System Based On Software Defined Radio

With the growing maturity of space technology,various countries have also put forward new requirements for satellite communications.The traditional satellite data transmission transmitter's frequency points,modulation modes and encoding methods are relatively fixed,and can not be realized flexibly and alterably after it was launched.Software defined radio proposed in 1990 s has the characteristics of ssoftware programmability.In order to solve the problem of single function and costly of the traditional data transmission transmitter,this paper proposes a data transmission transmitter based on software defined radio technology,which can be used to realize the reconfiguration of frequency,modulation mode,data rate,bandwidth and channel coding in orbit.Therefore,the software defined radio platform and up-conversion system were studied in this paper.First of all,the scheme of data transmission transmitter based on software defined radio was designed after researched the basic theory of SDR.Then,the system composition of the software defined radio platform was studied,and the scheme of up-conversion system of X band was designed.This paper studied the composition of up-conversion system in X band,established the up-conversion system scheme and the main performance index.Then,the paper studied the principle of the up-conversion system module,and carried out the circuit design,RF simulation and system function test of the modules such as mixer,amplifier,frequency synthesizer,filter,etc.The design realized the low cost and low power dissipation with one mixer.The transmitter system can be used for microsatellite platform.Combined with the software defined radio platform and the X band up-conversion system,the reconfigurable data transmission transmitter system was tested.The reconfigurable function of the digital transmitter on the satellite platform was realized.The test of digital transmitter in software defined radio platform was verified.The modulation mode,data rate and output power of the transmitter can be reconfigured,and the test results meet the requirements of the design index.