Research Of Signal Processing Technology In Passive Bistatic Radar On CPU+GPU

With the continuous development of information technology,the traditional active radar is faced to various challenges such as the low-altitude penetration,the electromagnetic interference,the stealth aircraft and the high-speed anti-radiation missiles.For meeting these threats,researchers of various countries continue to explore new systems of radar technology,and the passive bistatic radar(PBR)is one of them.The PBR is a passive radar,which does not have a signal transmitting device and relies on non-cooperative radiation sources for passive detection.Its system is relatively concealed and can not easily destroyed by the enemy.The early PBR used FPGA and DSP chips to build signal processing systems,but the method used many DSP development boards,so the hardware platform was complicated and the design and debugging of the hardware circuit is difficult.That lacks flexibility and can not be easily operated.The development of high performance computing(HPC)technology provides a technical foundation for the software of radar systems.In this paper,CPU+GPU heterogeneous platform is adopted to realize the signal processing of PBR.The main work is summarized as follows:1.Because the electromagnetic environment of the PBR is very complex,the received signal contains target echo signal,the strong clutter and the multipath interference.So it is necessary to perform clutter suppression processing on the echo signal.In this paper,multicore CPU is used as the platform to realize the clutter suppression module of the PBR signal processing system.Because the running speed of clutter cancellation algorithm is not ideal,the real time has a big gap with the theoretical running time and it can not meet the real-time requirements of the system,so this paper proposes an implementation method which base on the Open MP programming.The method is that segmenting the signal data,adding overlapping redundant data,and using Open MP programming instruction statements to call CPU cores.Each core executes a thread which is responsible for processing a piece of data,and the processed data need a de-redundant processing.This method makes full use of the multi-core characteristics of the CPU and greatly reduces the calculation time.2.After clutter suppression,the energy of target's echo in the recevied signal of the PBR is still lower than that of the noise platform,so it is difficult to observe directly.Therefore,it is necessary to perform range-doppler(R-D)processing on the echo data to improve the signal-to-noise ratio of the target,and extract the target information through constant false alarm detection(CFAR).In this paper,the GPU platform is used to implement the R-D processing module and the CFAR module,and the many-core characteristic of the GPU is used to reduce the running time and improve the calculation efficiency.The FFT operation in R-D processing occupies a large amount of calculation resources,which is reduced by extraction operation.In order to prevent spectrum aliasing,anti-aliasing filtering is performed when decimating data.3.After the CFAR,it is necessary to observe the target through PPI display terminal from the point trace.In this paper,the GUIDE development environment of MATLAB software is used to create a complete GUI interface to realize the design and development of radar PPI display.The interface simulates the rotation of the actual antenna,displays the change of azimuth angle,and supports control functions such as start,pause,and reset.The PPI display terminal can display the processing results of the measured data intuitively and clearly,which is convenient for verifying the correctness of the radar signal processing program and analysing result.