Development Of Frequency Monitor Subsystem Of High-frequency Radar Based On FPGA

High frequency band that high-frequency radar operated in is a crowd electromagnetic environment and time-varing.To avoid those interferences,a frequency monitor module,which could monitor the electromagnetic environment of the radar station in real time and select the optimal operating frequency,is an necessary subsystem in the radar system.At the early stage,the frequency monitor channel and the detection channel of the high frequency radar are constructed(formed)by the specific Digital Down Converter(DDC)chips with DSP signal processor.This kind of architecture is capable of providing the basis requirements of signal processing,but the production cost is expensive,and the flexibility is limited.Recently,as the development of software defined radio and Field Programmable Gate Array(FPGA)technology,adopting FPGA receiver with generic server as a new hardware composition for radar signal processor has gained popularity in high-frequency radar programming.In this paper,a frequency monitoring system is designed and manufactured for the practical requirements of a compact high-requency radar system.Based on the concept of the software defined radio system,the frequency monitor channel is seperated into two parts according to the function of the frequency monitor subsystem.Two functional modules have been implemented on the FPGA data acquisition card and on the generic server.Radio frequency sampling architecture is used in the signal preprocessing part of the frequency monitor channel.To extracte the electromagnetic environment of the radar station in real time,a cycle local oscillator sweep is utilized.Furthermore,we analyze the feature of multi-rate signal processing module is,and design the implementing scheme of multistage filtering decimator to fit with the system requirements.The feasibility of the scheme is verified by the simulation of Matlab and ISE.Besides,the signal preprocessing part of the frequency monitor channel including the DDC and FFT,is implementated with an FPGA embeded QT1138 card.In the signal processing part of the frequency monitor channel,we first procedure the working sequences and signal processing procedures.The paper focus on the signal processing algorithm in the “resistance interference” and “frequency primary selection” stages.The performance of the target algorithm is verified and analyzed with radar measured data.Finally,the paper realizes the analysis and processing of the electromagnetic environment data uploaded by data acquisition card,and completes the operating frequency recommendation at “frequency primary election” stage,and achieves the function of the frequency monitor channel.