Research On Dynamic Digital Channelized Receiving Structure And Subband Detection Algorithm

Digital channelization techniques have advantages of large instantaneous processing bandwidth,wide receiving band,reduce data rate,and improve signal-to-noise ratio(SNR),etc.,it is often widely used in radar and communication receiving systems.These systems capture the instantaneous signals in a larger frequency band,and then perform a comprehensive real-time analysis in several aspects such as time domain,frequency domain,and modulation domain.At the same time,the signal in the receiving frequency band has the characteristics of wide frequency band,non-cooperative,and a priori information uncertainty.Therefore,it is very necessary to study a more efficient dynamic digital channelized receiving structure.In the structure,the existence and position of the signal are determined by detecting and judging the output of each sub-band.The correct detection of the sub-band signal determines that the subsequent processing can accurately reconstruct the input signal,which plays a key role in the digital channelized structure.Therefore,this paper mainly studies the digital channelized receiving structure and sub-band detection algorithm.The main research contents are as follows:Firstly,the efficient design of the digital channelized receiving structure is deeply studied.Due to the spectral aliasing problem and channel ambiguity caused by the signal occupying multiple sub-band,a dynamic digital channelized receiving structure based on odd-even channel superposition is proposed in combination with polyphase parallel filtering and practical application requirements.The main processes are signal preprocessing,analysis filtering,sub-band detection,and comprehensive filtering.In the specific design,a half-band filter is used to simplify the signal preprocessing process,and a complex exponential modulation filter and polyphase decomposition of filter coefficients are used to optimize the analysis-synthesis filtering process.In this way,the whole structure is simplified to only need to design the corresponding half-band filter and low-pass prototype filter according to the system parameters.It is verified by experimental simulation that an efficient structure can be obtained based on the above simplification and derivation.It is shown that there is no need to design a more complex filter bank to meet the requirements of complete reconstruction,by taking advantage of the characteristics of the half-band filter and the polyphase filter structure.Therefore,the calculation amount in the efficient receiving structure is reduced,and the operation efficiency is improved.Secondly,the detection algorithm used in sub-band detection in the dynamic digital channelized receiving structure is studied.Because the traditional detection algorithm is easily affected by noise and the detection performance is not high under low SNR.Based on random matrix theory,this paper studies the detection algorithm of sub-band output by analyzing eigenvalues.Most of the existing eigenvalue-based detection algorithms use the maximum eigenvalue and the minimum eigenvalue to construct the test statistic,and the threshold is determined according to the distribution characteristics of the maximum eigenvalue.On the one hand,these methods do not use other remaining eigenvalues,ignore the intrinsic relationship between all eigenvalues in the sampling covariance matrix,and waste the information in the sampled data to a certain extent.On the other hand,the detection threshold expression of algorithms such as the difference between eigenvalues is related to noise,so the detection performance will be affected by noise.Therefore,this paper uses more eigenvalue information to construct the test statistic of the algorithm,in order to further improve the accuracy of the detection threshold.A sub-band output detection algorithm based on the ratio of the difference between the maximum and minimum eigenvalues to the average eigenvalue is proposed,and the detection threshold is derived by using the limit distribution law of the minimum eigenvalues.And the proposed algorithm is optimized according to the eigenvalue information obtained from all sub-band signals.Finally,the correctness and effectiveness of the proposed algorithm are proved in the proposed dynamic digital channelized receiving structure.