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CW雷达多普勒测速实验教学装置设计
Experimental Device Design of CW Doppler Radar Velocity Measurement
DOI: 10.12677/APP.2022.126038, PDF, HTML, XML, 下载: 498  浏览: 863

Abstract: An experimental device for target speed measurement based on continuous radar’s Doppler effect was designed. The radar echo signal was collected by a radar transceiver with 10.525 GHz center frequency. The intermediate frequency (IF) signal was generated by a mixer and amplified by AD620, and the data acquisition of the IF signal was completed by 16-bit high precision ADC. The frequency of the IF signal was identified by Fast Fourier Transform (FFT); the Doppler frequency and target radial velocity were then obtained. An experimental platform was built by using the structure of stepping motor and screw nut. The experimental results show that the measurement error of target radial motion speed is less than 1%. The experimental device is expected to be used in the course teaching demonstration, such as College Physics and Communication Electronic Circuit.

1. 引言

2. CW雷达多普勒测速原理

CW雷达测速的基本原理是大家所熟知的多普勒效应：当运动目标接近雷达时，回波信号频率相对于雷达发射信号频率变高；目标远离雷达时，回波信号频率变小。雷达发射信号与回波信号频率的差值定义为多普勒频率(Doppler Frequency)：

${f}_{d}=\frac{2{v}_{r}}{\lambda }$ (1)

${u}_{t}\left(t\right)={A}_{tm}\mathrm{cos}\left({\omega }_{c}t\right)$ (2)

${u}_{r}\left(t\right)={A}_{rm}\mathrm{cos}\left({\omega }_{r}t+\phi \right)$ (3)

${A}_{tm}\mathrm{cos}\left({\omega }_{c}t\right)\cdot {A}_{rm}\mathrm{cos}\left({\omega }_{r}t+\phi \right)=\frac{{A}_{tm}\cdot {A}_{rm}}{2}\left\{\left[\mathrm{cos}\left({\omega }_{c}+{\omega }_{r}\right)t+\phi \right)\right]+\left[\mathrm{cos}\left({\omega }_{r}-{\omega }_{c}\right)t+\phi \right)\right]\right\}$ (4)

Figure 1. CW Doppler radar velocity measurement architecture

3. CW雷达多普勒测速实验系统

Figure2. CW radar velocity measurement experimental device diagram

Figure 3. IF signal amplification and acquisition architecture

Table 1. CW radar velocity measurement device specification

4. 实验结果与分析

${v}_{r}={f}_{d}\cdot \frac{\lambda }{2}=1.40×\frac{28.50}{2}=19.95\left(\text{mm}/\text{s}\right)$ (5)

Figure 4. IF signal (×100) with DC bias

Figure 5. FFT spectrum of radar IF signal

5. 结束语

Figure 6. SFFT cloud image of radar IF signal

Timer中断编程，步进电机控制，VC++编程，FFT分析，雷达混频器与IF信号的调理及其采集等诸多知识点，有助于培养学生综合利用专业知识解决实际工程问题的能力，具有较好的实验教学效果。

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