Research On FMCW Radar RF Front End And Baseband Board

Frequency modulation continuous wave radar widely used in military field in the early stage because of its characteristics of long measuring distance,high measuring accuracy,strong anti-interference ability,flexible use,etc.Later,with the rapid development of integrated circuits,the manufacturing cost of radars was rapidly reduced,and frequency modulation continuous wave radars began to be widely used in civil industries such as automobile collision prevention,foreign object detection on airport runway,and detection of small civilian unmanned aerial vehicles.In this paper,a baseband signal processing board and a frequency modulation continuous wave radar radio frequency front-end circuit board are studied and designed respectively based on the background of frequency modulation continuous wave radar detecting small civilian unmanned aerial vehicles.(1)Based on DSP+FPGA architecture,a baseband signal processing board with strong computing capability and fast data transmission is researched and designed.The DSP chip TMS320C6678 has high operating speed and strong computing power,and can be used for the calculation of complex functions.The FPGA chip XC7K325TFFG900 has many input-output interfaces and rich editable resources,and can be used for logic control,timing control,data transmission,and the implementation of preprocessing algorithm.The DSP and FPGA are equipped with 4 and 2 DDR3 memory chips,respectively,thereby provided 4GB and 2GB of storage space,respectively.SRIO interface is used as the fast data transmission interface between the DSP and FPGA,and the data transmission speed can reach up to 20 Gbps.The power supply demand and power on time sequence of the baseband signal processing board are analyzed,and the power circuit is designed.The clock signal requirements of the baseband signal processing board are analyzed,and the clock circuit is designed.Finally,the design of the schematic and PCB layout of the baseband signal processing board is completed,and the physical processing is completed.The baseband signal processing board has high performance computing capacity and fast data transmission capacity,which can meet the requirements of the system.(2)A radio frequency front-end circuit board of the frequency modulation continuous wave radar with low phase noise,high output power and long detection range was researched and designed.The radio frequency front-end circuit board mainly includes transmitter and receiver.The phase-locked loop is used as the frequency source of the transmitter,and its working principle,noise,and link gain are analyzed in detail.The zero intermediate frequency scheme is used as the design scheme of the receiver,and the circuit of the receiver is analyzed in detail.This article designs a radio frequency front-end circuit board for frequency modulation continuous wave radar,and its transmitter is designed and simulated in ADIsim PLL software.According to simulation results,the loop bandwidth is 264 k Hz,phase margin is 45.75°,and phase noise is-85 d Bc/Hz@10KHz,and can generate the sawtooth waveform frequency modulation continuous wave signal with frequency sweep bandwidth of 50 MHz and frequency sweep time of 200 us.The radio frequency front-end circuit board is processed and tested.The test results show that the radio frequency front-end circuit board can generate the required sawtooth waveform frequency modulation continuous wave signal.However,the output power is low,only-0.29 d Bm.In order to improve the output signal power of the radio frequency front-end circuit board,a power amplification scheme is added,and a power-on sequence control circuit is designed.Finally,the final radio frequency front-end circuit board is processed and tested.The test results show that the output power of the radio frequency front-end circuit board can reach 31.55 d Bm,and meet the design indexes.The baseband signal processing board designed in this paper can not only be used to detect frequency modulation continuous wave radar of small civilian unmanned aerial vehicles,but also can be used in automotive radar,gesture recognition,image processing and other applications.It has strong universality.Similarly,the radio frequency front-end circuit board designed in this paper can not only be used to detect small civilian unmanned aerial vehicles,but also provides implementation solutions for liquid level measurement,automatic driving,and foreign object detection on airport runway.