Design Of K Band Speed Measuring Radar

With the increasing number of vehicles,people's travel tools are more convenient,and the rate of traffic accidents also increases year by year.In order to reduce the traffic accident rate,it is particularly important to design a small vehicle mounted instantaneous speed radar.Compared with the traditional coil speed measuring instrument,Doppler radar tachometer can achieve instant speed measurement,suitable for various weather conditions,and is small in volume,easy to install,debug and maintain.Most importantly,the accident rate of vehicles can be reduced.This paper first introduces two kinds of radar speed measuring systems: continuous wave velocity radar and pulse speed radar.On the basis of analyzing the advantages and disadvantages of the two system systems,the point frequency CW radar system,which is suitable for the near range speed measuring radar,is selected.Then we introduce the technical indicators of the speed measuring radar,analyze the advantages and disadvantages of the super heterodyne and zero if structure,and find out the reasons for choosing the zero if architecture.On the basis of the detailed system block diagram and the reasonable distribution of the gain of the receiver,the whole performance software simulation of the RF front end scheme of the speed measuring radar is carried out,and the feasibility of the scheme is verified.In order to improve the system's ability to resist noise and interference,the design of the shielding cavity is completed by the selection of the modules and circuit design and layout design of the PLL fixed frequency source,bandpass filter,power amplifier,power divider,low noise LNA,mixer,baseband circuit and so on.Finally,the modules of each module of the assembly are tested.The circuit test follows the principle of "first realizing function and readjustment performance",and debug the transmitting branch and receiving branch respectively.Finally,the performance test of the whole machine is carried out.The test results are as follows: the operating frequency of the transmitter: 24 GHz,output power: 9.44 dBm,receiver RF gain: 17.5dB,noise coefficient: 2.9dB,intermediate frequency bandwidth: 16 KHz.The test results show that the design basically meets the design requirements.