Design And Development Of A Multifunctional Radar Signal Generator

Since its birth,radar technology has been widely used in military and civilian fields,and has made great achievements in communication,positioning and meteorology.At the beginning of the birth of radar,various performance tests were carried out by means of outfield flight test,but this test method was limited by environmental and cost factors.The radar signal generator can simulate the radar echo signal,which breaks through the limitation of field flight test mode and is widely used in radar design,debugging and maintenance.The multi-function radar signal generator designed in this thesis can realize the output of single frequency continuous wave,single frequency pulse,linear frequency modulation and intra pulse dual frequency signals with different frequency and amplitude combinations.In order to meet the technical requirements of signal generator,FPGA +DDS architecture and PC software are used to design and implement a multi-functional radar signal generator in this thesis.In the structure of this thesis,three typical frequency synthesis technologies of signal generator are introduced,which are indirect frequency synthesis technology,direct analog frequency synthesis technology and direct digital frequency synthesis technology(DDS).Their working principles and characteristics are analyzed and compared.In this thesis,the design of radar signal generator is based on DDS technology.Then,according to the requirements of the project,the overall design scheme,hardware logic design and software design are discussed.The whole scheme includes software program design,hardware logic design,DDS signal synthesis and signal processing.The master computer software is designed and developed on Windows10.The software is responsible for human-computer interaction.The users input the signal parameters of radar signal generator and communicates with the slave computer through the universal asynchronous receiver / transmitter(UART).The architecture of FPGA +DDS is adopted in the hardware.FPGA as the central system receives the parameter data of the master computer,controls the DDS to generate signals,and feeds back the running state information of the whole radar signal generator.AD9910 is adopted int the DDS chip,which has excellent signal output performance.In a variety of working modes,it can control the built-in register to modulate the signal through programming.The signal processing circuit is designed to optimize the signal generated by DDS in order to achieve the technical indicators.Finally,the debugging of software and hardware system of radar signal generator is introduced in this thesis,including communication test and signal output test.In the communication test,the master computer software can normally control the slave computer system to output the corresponding waveform and obtain the operation status information.In the signal output test,different signal parameters are set to output single frequency continuous wave,single frequency pulse,linear frequency modulation and intra pulse dual frequency signals.The functional indexes(frequency,amplitude,pulse width,repetition frequency and bandwidth)of the signal are consistent with the parameters set by the software.The spectrum test of the performance indexes shows that the spurious and noise suppression are above 60 d Bc,which meets the technical requirements of the project.