Design And Implement Of Digital Broadcasting-based Passive Radar Receiver

Passive radar is a radar that does not emit electromagnetic wave signals by itself and uses the third-party radiation source for target detection.It has the advantages of no radiation pollution,strong anti-strike ability,and convenient network detection.As digital signals continue to be popularized and promoted in countries around the world,passive radar can use a wider variety of illumination sources,including broadcast television signals,satellites,communication base station signals,and Wi Fi.Due to the large transmission power,wide coverage and high popularity of digital broadcasting and television signals,in recent years,passive radar based on this signal has gradually become the focus of research at home and abroad,and related hardware devices and signal algorithms have also developed rapidly.However,due to the large bandwidth of TV signals and the increasing number of radar antenna arrays,the current radar receiving systems are facing enormous acquisition and transmission pressures,which need to meet the requirements of multi-channel signal acquisition and data stable transmission.Based on the characteristics of digital broadcasting and television signals in China,this paper designs a radar receiving system for passive radar of digital broadcasting and television.The system has the characteristics of multi-channels,high data transmission rate,and can sample multiple TV channels at the same time.It uses the scheme of analog front-end conversion with digital board sampling,and its working frequency range can cover the whole digital TV frequency band.It uses the JESD204 B protocol as the data bus between the ADC and the FPGA,which greatly simplifies the hardware circuit design,and uses the QSFP fiber transmission method to realize the communication between the FPGA and the host computer,ensuring the stability of the transmission link.Time synchronization between multiple radar receiving systems can be realized combining with GPS module and second pulse.Then,the UAV detection experiment of multi-frequency passive radar is carried out by using the designed system,and the detection performance of passive radar under multifrequency mode is studied firstly.In this experiment,three different frequency digital TV signals are used to detect the same UAV target,and the three-dimensional model of the UAV is established by means of GPS track.The variation of RCS during UAV flight and the difference of RCS between different frequency irradiation sources are simulated and analyzed.On this basis,the multi-frequency detection method using the maximum SNR improves the detection continuity of the passive radar and the stability of the target's SNR.The simulation and measured results show that when the passive radar uses different radiation sources for detection,the RCS and the radar's overall detection results have obvious frequency differences;The multi-frequency fusion can effectively improve the detection probability of the passive radar and make the SNR of the target more stable.The above analysis has certain guiding significance for improving the target detection performance of the passive radar.