Special topic of MIMO Radar (0) - General Chapter

General chapter

1、 What is millimeter wave radar

Millimeter wave refers to the wavelength between 1-10mm The electromagnetic wave of , The wavelength is short 、 The frequency band is wide , It is easier to achieve narrow beam , High radar resolution , Not susceptible to interference . Millimeter wave radar measures the relative distance of the measured object 、 Current speed 、 High precision sensor for azimuth , It was used in the military field in the early stage , With the development and progress of Radar Technology , Millimeter wave radar sensors began to be used in Automotive Electronics 、 Unmanned aerial vehicle (uav) 、 Intelligent transportation and other fields .

2、 Development status of vehicle mounted millimeter wave radar

At present, the frequency band of vehicle mounted millimeter wave radar is mainly concentrated in 77GHz.24GHz The radar measurement distance is short , It is mainly used in the rear of cars （24GHz Radar will be eliminated ）.77GHz The radar measurement distance is long , It is mainly used in the front and both sides of the car . The frequency band of the global vehicle mounted millimeter wave radar will converge to 77GHz Frequency band （76-81GHz）.
77GHz Than 24GHz Many advantages of ：
1, The frequency band is higher , Provide higher measurement accuracy , Can detect smaller objects .
2, Ultra wide band , High resolution can detect ultra short distance , Strong anti-interference ability .
3, The antenna is proportional to the wavelength , Volume, size and weight miniaturization .

chart 1 24G and 77G Two dimensional test results

besides ,AIP、SIP Such system level integration technology makes millimeter wave radar develop towards miniaturization . Large scale array （48 Hair 48 closed ）、 Multi chip cascade 、MIMO、 Exploration and application of pitch high resolution technology , Millimeter wave radar will be endowed with more powerful scene awareness and situation recognition capabilities .

3、 Why use MIMO technology

The biggest disadvantage of millimeter wave radar is its low angular resolution , Vehicle mounted millimeter wave radars generally use phased array antennas for angle measurement , Its antenna design is directly related to the signal wavelength . Under the same aperture ,77GHz Than 24GHz It can form a narrower beam width , With higher angular resolution , This is very important for long-range radar detection , This is because the arc length corresponding to the angular resolution unit in the polar coordinate system increases with the increase of distance , for example 5 The resolution of degrees is 200 The arc length at meters is about 17 rice , Wider than ordinary roads , The target cannot be distinguished horizontally .
For millimeter wave radar system engineers , The improvement of angular resolution is far from enough , So we need to introduce MIMO technology , Expand the physical aperture from the perspective of signal processing , Further increase the angular resolution . So ,MIMO Technology is a signal processing algorithm based on hardware architecture .
About MIMO Definition of radar , as well as MIMO The advantages and disadvantages of radar , Please refer to ：《MIMO On Radar 》

4、MIMO Millimeter wave radar and 4D The relationship between millimeter wave imaging radar

4D Millimeter wave imaging radar essentially belongs to MIMO Millimeter wave radar , It is in the existing MIMO Based on millimeter wave radar , It not only increases the pitch dimension antenna array , Thus, the pitch dimension resolution is improved , And it adopts large-scale array or multi chip cascade Technology , Increase the number of receiving and sending channels , Improved azimuth resolution . The target detection result is upgraded from single point to point cloud .

It is because MIMO Many advantages of radar , The vehicle mounted millimeter wave radar has caught up MIMO technology “ Free ride ”, Face 4D Millimeter wave “ imaging ” Radar development . This column will combine 4D Millimeter wave imaging radar is introduced to you MIMO Radar technology , Prepare to introduce the following , It is expected to be updated within one year , Welcome to subscribe early （ There are many articles in the later stage, and the price will rise ）.

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One 、4D Millimeter wave radar hardware system architecture

Two 、4D Optimization design of millimeter wave radar antenna array

1、 Key points of antenna design

2、4D Antenna array layout design

3、 ... and 、4D Millimeter wave radar waveform design

1、 Waveform design technology points

2、TDM wave form

3、OFDM wave form

4、CDM wave form

5、BPM wave form

Four 、 4D Millimeter wave beam shaping

5、 ... and 、 4D Millimeter wave radar error correction

1、 Error classification and influence

2、 Error correction technology

6、 ... and 、 4D Anti jamming Design of millimeter wave radar

1、 Types and characteristics of interference

2、 Anti interference methods

7、 ... and 、 4D Millimeter wave radar DOA It is estimated that — Angle measurement

1、 Monopulse angle measurement method

2、 Various super-resolution algorithms

8、 ... and 、 4D Millimeter wave radar target detection — Ranging and speed measurement

1、 Ranging methods

2、 Speed measurement method

Nine 、 4D Millimeter wave radar data processing

1、 Point cloud fusion and clustering

2、 Track processing

3、 Micro Doppler analysis

4、 Point cloud recognition