Research On Characteristics Of A Wideband Digital Receiver

Broadband digital receiver technology as one of the important technologies in the special war field,after the widespread application of software radio technology,it has developed rapidly.Due to the wider frequency band occupied by communication signals,the signal form is complex and variable,and the requirements for wideband digital receivers are getting higher and higher,Therefore,it is imperative to carry out research on Communication signal wideband digital reconnaissance receiver.In this paper,2ASK,FM,CW,2FSK,4FSK,AM modulated signals in strong noise environment are treated,and studied the channelized receiving scheme based on polyphase filtering,Hybrid modulation signal classification and recognition algorithm based on power spectrum and quadratic power spectrum features and blind estimation algorithm for signal carrier frequency parameters are studied.Combining the current status of domestic broadband reconnaissance digital receivers,main research wideband digital receiver algorithm for detecting received signals based on two-stage channelization scheme of polyphase filter bank,compared to traditional channelization structures,in the case of achieving the same output signal bandwidth,required less number of channels,the occupied hardware resources are greatly reduced,solved the problem that the front-end sampling rate is not matched with the back-end data processing rate.Simulation experiments verify the feasibility and effectiveness of the two-stage channelization process;Analyzed reliability of classification operations using mixed signal power spectrum and secondary power spectrum characteristics,it is proposed to divide the signals into major categories,then subclass them in the large categories,by calculating the signal characteristic parameters and setting the threshold to achieve,among them,this paper proposes to apply parameters ?₄₂^f to distinguish between frequency modulated signals,and on the original basis,the parameters ?_max and the number of peaks N1 and N2 are improved,simulations show that these improvements greatly improve the accuracy of recognition.By comparing the performance and advantages and disadvantages of traditional frequency measurement algorithms,find a better frequency measurement method,and improve the frequency error caused by phase overlap and the limitations of the carrier frequency measurement range,that is to turn the fixed delay time into an iterative calculation method based on auto-correlation delay time variable.The simulation shows that the method has high frequency measurement accuracy and meets the application requirements.