The Fast Detection Of Broadband Signal And Its Implement On FPGA

Refer to the problem on intensive computation of copy correlation processing in detecting multi-channel underwater wideband signal(LFM signal),the paper studies the fast detection method to reduce the amount of calculation,mainly containing the down-sampling in the time domain and correlation in the frequency domain.Finally,the fast detection method is implemented on the FPGA platform.Firstly,the received signal is orthogonally filtered to be complex analytic signal.Combined with multi-rate signal processing,the analytic signal is down-sampled into a low throughput data stream,reducing the pressure of the subsequent copy correlation detection.Adopting the idea of decimating former and filtering later,polyphase filter is applied in the down-sampling process to further reduce the amount of calculation and save storage.To improve the operating efficiency of fast detection,the paper implements sliding correlation in the frequency domain though Fourier transform.By means of FFT algorithm,processing efficiency can be significantly improved to achieve the fast detection purpose.The paper studies the fast implementation of down-sampling copy correlation based on FPGA for signal detection,with modular design,it improves portability and scalability greatly,mainly containing the design of polyphase filter,frequency domain correlator and threshold decider.Modelsim is used for timing simulation to verify functionality of each module,and Quartus is used as synthesis tool for the design,ultimately signal detection is implemented on CycloneIV device.Results of system test and the data processing of lake test show that the down-sampling copy correlator can achieve the aim of signal detection fast,reaching the same performance of original copy correlator which does not implement down-sampling process.