Signal Processing Technology Of Digital TV Based Passive Radar

The passive radar is a special form of bistatic/multistatic radar,which uses the radio,television and satellite signals as the non-cooperative illumination for target detection.It has many advantages over the traditional radar in battlefield,including the electronic reconnaissance resistance,attack avoidance,stealth target detection,and so on.With the development of digital technology,the digital television signal has gradually replaced the analog television signal and has covered a large area of the earth.This provides a convenient condition for the development of the passive radar based on the digital television signal.The digital television signal has the characteristics of wide bandwidth,stable transmitting power,and large coverage at low altitude.Therefore,the signal is widely studied in radar field in recent years.This paper uses the digital television signal as the illumination and studies the corresponding signal processing technology.It mainly involves some pre-processing operations before target detection and the improvement of target detection technology.The passive radar adopts the dual-channel antenna receiving mode.One channel points to the direction of the signal radiation source for receiving the direct signal.The other channel receives the target echo signal.The energy of the target signal in the echo channel is weak.In addition,it also contains high-energy direct signals,multipath interference,and noise.These undesired signals in the echo channel have a bad impact on the coherent accumulation results.Some distant or weak targets can be easily submerged by these undesired signals,which may cause false or missed alarms.Therefore,clutter suppression processing before target detection is very important.In addition,the frame structure of the digital television signal contains a guard interval or a cyclic prefix.These signals can interact with the target signal,resulting in a fuzzy secondary peak during the process of coherent accumulation.This seriously affects the performance of the target detection result.Therefore,the suppression of the secondary peak is also indispensable in pre-processing before the target detection.This paper focuses on the target detection phase of the passive radar based on the digital television signal.Extending the coherent accumulation time is a commonly used method to increase the signal-to-noise ratio.The digital television signal has a wide bandwidth,so the detection system has a high range resolution.However,the detection result suffers from the distance migration problem because of the long accumulation time.To solve this problem,this paper presents a method of distance migration compensation based on signal time-division segmentation.The method does not require the priori distance and speed information of the target and has the real-time processing character.In addition,when the target maneuvers,the echo signal has the phase error,so that the accumulation result will appear to span the Doppler unit.To solve this problem,this paper proposes a reconstruction function based on minimizing the phase error.The proposed method does not estimate parameters of the phase error and is suitable for compensating any type of phase error.Besides,it has good environmental adaptability and fast convergence speed.The practical digital television signal is used in the simulation experiments to verify the correctness and feasibility of the proposed method.