Research On Radar System Based On Hybrid Frequency Shift Keying Waveform And Frequency Scanning Array

Short-range localization and vital sign detection are two hot research topics in the fields of medical monitoring,driver assistance,and indoor navigation.In fact,in many scenarios,they are cross-integrated: for example,detecting hidden intruders by capturing the vital signs of the target,or tracking the trajectory of patients and monitoring their vital signs in real time.In these applications,microwave radar systems have their intrinsic advantages compared with conventional contact-required sensors or camera-based solutions,such as non-contact,penetrability,and unaffected by light or temperature.Radar sensors have been widely studied and applied.However,current radar sensors also have limitations.One of the biggest challenges is how to achieve multi-target vital sign monitoring and positioning at low cost and high accuracy.Traditional CW radars have high accuracy in detecting vital signs,but they lack ranging capabilities.FMCW and UWB radars measure the range and vital signs of targets at the cost of large bandwidth and complex structures,but the measurement accuracy of small displacements is limited;The acquisition of angle information is often achieved through complex beamforming structures such as phased arrays.In response to this challenge,this paper proposes a hybrid frequency shift keying radar waveform,which combines frequency scanning antenna and frequency shift keying(FSK)waveform to achieve multi-target vital sign detection of stationary human bodies and trajectory tracking of a moving human target.The system has the following advantages:1.A FSK-FMCW hybrid modulation waveform is proposed to solve the inherent contradiction between the maximum unambiguous distance and ranging accuracy of the FSK system.The small bandwidth FMCW provides a distance reference,which improves the FSK system without affecting the ranging accuracy.2.A scheme combined hybrid frequency shift keying waveform and frequency scanning arrays is proposed.FSK signals of different carrier frequencies are used to sequentially excite the frequency scanning antennas,and the target angle information is obtained through beam scanning.At the same time,the FSK radar in each beam detects target movement and distance information.Compared with the method of measuring the angular and range with the continuous frequency modulation signal exciting the frequency scanning antenna,this scheme overcomes the contradiction between the angular resolution and the distance resolution.3.It combines the advantages of the FSK system and frequency scanning antenna.The system has high displacement measurement accuracy,ability to obtain the target distance with a small bandwidth and flexible beam formation.This paper analyzes the working principles of the proposed radar,then builds the system,and verifies the feasibility of the scheme through experiments.The system finally detects and locates multi-target vital signs in the stationary human target detection scene,and the distance measurement error is within 10%.In the moving human target detection scene,the tracking of the target moving trajectory is realized,and the tracking result is consistent with the actual movement.