Research And Design Of 24GHz Radar Sensor

The 24 GHz radar system can be used for long-distance speed measurement and ranging.When using a microwave signal in the 24 GHz ISM band to detect a long-range target,a part of the incident wave signal will be reflected by the target.The echo signal will have a time delay if the target is stationary,or a Doppler effect will occur if it is a moving target.The echo signal is mixed with the incident wave signal to output an intermediate frequency signal,which contains the Doppler information of the target,and can be used to extract information about the speed,distance,and direction of motion associated with the target.Based on the advantages of strong penetrating power and good anti-interference performance,the 24 GHz radar can be applied to automotive anti-collision,drone soft landing,robot obstacle avoidance and smart home applications.This paper mainly studies two aspects of 24GHz radar sensor,including system design and signal detection.The former improves the complexity of the whole system and signal processing mode through reasonable scheme design.It uses highly integrated technology and programmable control to improve the modularity and ease of debugging of the hardware system.The latter improves the ability to identify low-amplitude IF signals from the RF front-end,by using programmable filter IC and low noise intermediate frequency amplifier.This paper mainly aims at the realization of the 24GHz radar sensor system,and records,summarizes the research process of the whole subject in the following sections:1.The principle of ranging and speed measurement of FMCW radar.Through the review of relevant papers and periodicals,the detailed block diagram of FMCW radar is studied.Based on this,the theoretical process of FMCW radar is derived by using formula.Further deepening the understanding of the FMCW radar,this information has important implications for the overall design of the radar system.2.An implementation scheme based on 24GHz FMCW radar system is proposed.In this scheme,a monolithic microwave initegrated circuit(MMIC)is used to replace the traditional T/R,designed by discrete component;a PLL is used for frequency synthesis This greatly reduces the size,power consumption and cost of the radar system.In addition,a programmable filter and a low noise amplifier are used for the processing of the intermediate frequency signal.The programmable filter has the advantages of accurate cutoff frequency,high phase matching and built-in controllable gain amplifier,which greatly improves the signal-to-noise ratio and weakens the low-frequency interference of the FMCW radar system to a certain degree.However,this also limits the minimum distance that the radar system can measure.The use of very low noise amplifiers to amplify the IF signal further enhances the ability to extract useful information.3.The HFSS electromagnetic simulation software is used to simulate the design of the transceiver antenna based on the 24GHz radar system.First understand the HFSS electromagnetic simulation software,master the software usage.On this basis,a single antenna unit is designed based on the basic theory of microstrip patch antenna,and then the feed network is designed for the entire antenna array by using the quarter-wavelength conversion principle and the Chebyshev optimal coefficient distribution ratio.The total gain of the antenna reaches 12dBm,and the beam width reaches 25~°×75~°.4.Write system software based on IAR software.First write the control part of each component to verify that every component of the radar system is working properly.Then there is the detection of the IF signal.