Research On Agile Signal Source Control System Based On FPGA

As a microwave signal generation equipment,the accuracy and stability of the output signal from the signal source system affect the performance of the entire microwave system.In recent years,with the development of microwave systems,the agile frequency signal source has received extensive attention.Because of its fast frequency switching characteristics,it can improve the anti-interference ability of radar and communication systems,so that it has a wide range of applications in the fields of frequency hopping communication,electronic warfare,and microwave measurement,etc.Therefore,it is of great significance to have a research of the agile signal source control system and achieve the control of the underlying microwave module to ensure the stable operation of the signal source system.This paper contains the design of FPGA-based agile signal source control system.The control scheme is designed according to the requirements of the underlying module.In order to achieve fast frequency switching speed,high frequency output accuracy and small RF power detection error,this paper has in-depth research in the design of agile frequency source module and the control of power system.The hardware circuit design of the control board is accomplished,and finally achieve the whole control of the signal source.The main research contents of this article are as follows:1.In the design of the frequency source module,in order to meet the requirements of frequency agility and high-precision frequency output,the AD9914 chip is used to implement direct digital frequency synthesis technology,and the control algorithms such as point frequency and frequency sweep are designed within the FPGA.The frequency output range is 1 M~1.4 GHz,the frequency step control is 1 mHz,the frequency is accurately synthesized in single tone mode,the frequency switching time is within 60 ns in sweep mode,and the module also has functions such as phase modulation.2.In the RF power control design,in order to solve the problem of error fluctuation caused by the temperature and frequency changes of the detector in the ALC system,the digital signal processing method based on the FFT algorithm is used,and the high-speed ADC is used to directly sample the RF signal to achieve stable power detection.In addition,in order to improve the speed and accuracy of power control,a master-slave FPGA structure is adopted,and digital and analog attenuators are controlled through a parallel interface.Finally,high-precision ALC power control with power detection algorithm error less than 0.1 dB and power control resolution of 0.01 dB is realized.3.According to the requirements of each underlying microwave module,the FPGAbased control board is designed.The control board implements communication with ARM is based on the EIM bus protocol.The control board is realized based on the eightlayer board and has the function of the whole control of the signal source.Finally,the agile signal source control system was tested to verify the functions of the FPGA-based control system.The test results can realize an output frequency range of 1 M ~ 1.4 GHz,a frequency switching time of 55 ns,and a power detection resolution of less than 0.1 dB and the power control resolution reaches 0.01 dB.The control system can realize stable host computer communication as well as underlying microwave module control,which meet the expected requirements,and the agile frequency signal source control system with high precision and power controllable frequency output was achieved.