Linear Frequency Modulation Short-range Detection Interference Analysis And Anti-interference Signal Processing Circuit Design

The linear FM short-range detection system has the advantages of no range blind zone,low transmit power,simple structure and so on.And it has been widely used in various fields,especially in the military field.The electromagnetic environment of modern battlefields is complex,which makes the system performance under man-made jamming and anti-jamming methods become the research focus.The paper is about the jamming analysis and anti-jamming signal processing of triangular FM short-range detection system.Firstly,the paper analyzes the beat signal of triangular FM detection system.A distance measurement algorithm based on CZT and a velocity measurement algorithm based on MTD are studied.The signal processing algorithm is verified by simulation.Secondly,the mechanism of AM jamming and FM jamming is analyzed by theoretical derivation and simulation analysis.The simulation results show that AM jamming and FM jamming degrade the system performance under specific parameters.According to the characteristics of jamming signal,an anti-jamming algorithm based on FrFT is proposed.The simulation results show that the algorithm can effectively suppress noise AM jamming,triangular AM jamming and partial noise FM jamming when the signal-to-jamming ratio reaches-10dB.Then,the hardware and software of system signal processing is designed according to index requirements.Hardware design includes design,processing,welding and testing of signal processing board.Software design is the FPGA implement of signal processing approach,which includes the derivation of discrete algorithm,program compilation and function verification.Finally,an integrated system is built up with the RF device and antenna to accomplish the field experiment and anti-jamming experiment.Field experiment indicates that the distance error and velocity error are within the allowable range of system indicators without jamming.Anti-jamming experiment shows that the anti-jamming algorithm can greatly reduce the distance error and velocity error when the jamming is exerted,leading to the system to meet requirements.