Research On Spectrum Adaptive Sensing Method And Implementation Of Wideband Radar Signal

With the rapid development of radar electronic warfare signal processing technology,the electromagnetic environment is becoming more complex and changeable.Traditional spectrum sensing architecture based on uniform digital channelization always exists the situation of signal cross-channel when facing radar signals with unknown parameters such as bandwidth and frequency,which causes the dispersion and loss of signal energy,affecting the correct processing of subsequent parameter estimation and signal sorting.In response to this problem,based on digital channelization of polyphase filter banks,this thesis improves a wideband radar signal spectrum adaptive sensing architecture to achieve adaptive reception and detection of radar signals in the electromagnetic environment.The main work includes the following aspects:(1)The efficient structure and theoretical derivation of digital channelization based on the polyphase filter banks are studied.And the shortcomings of the spectrum sensing architecture based on this digital channelization in the face of complex electromagnetic environments are analyzed.Besides,the advantages and disadvantages of architectures based on subchannel fusion and based on direct digital down converter by STFT are introduced.Based on this,a wideband radar signal spectrum adaptive sensing architecture is proposed,which laies the foundation for subsequent research.(2)A multi-channel blind signal adaptive threshold detection algorithm based on time-domain autocorrelation is studied.The algorithm is simple to implement and has good performance,which is easy to implement by FPGA.After adaptive threshold detection,an STFT-based cross-channel signal decision method is improved.This method can not only discriminate wide-band cross-channel signals,but also eliminate false signals caused by transition bands of digital channelized prototype filters.(3)A design method of variable bandwidth FIR filter is researched.This method can approach the filter designed by the equal ripple approximation method to a certain extent.The algorithm is simple and the corresponding filter coefficients are easy to generate.In addition,for the high-speed parallel processing of FIR filtering,the FFA structure is studied,which reduces the resource consumption when FIR digital filters are implemented in parallel.(4)According to the improved spectrum adaptive sensing architecture,the implementation of each module on the FPGA platform is studied,the internal implementation structure of each module and the multiplier resources that need to be consumed are analyzed,and the system simulation of the implemented modules is finally performed.It verifies the implementability and correctness of the architecture.