Research On Waveform Design And Signal Processing Method For Integration Of Radar And Communication

The mode of independent development has limited the speed of capacity growing of modern diverse electronic equipment.Aiming at the emerging problem of electro magnetic compatibility,hardware redundancy,inefficiency of power and overcrowding in the electromagnetic spectrum,increasing number of researches are focusing on the integrated design of advanced multi-function radio frequency system,by which the repetition of the underlying hardware,the inefficient power utilization and the conflict in electromagnetic spectrum will be relieved.In this background,the dissertation started the research on the integrated waveform design of the most common systems of radar and communication.Based on the analysis on the similarities and differences between radar and communication in the terms of physical conception,hardware structure and signal processing procedure,two novel integrated waveforms of radar and communication with operability have been proposed.The performance analysis and corresponding signal processing procedure are also considered.The following provides a brief summary:From the angle of waveform design for the integrated radar and communication system in signal antenna system,frequency shift keying(FSK)modulation is employed into the common radar waveform-step frequency(SF)signal.At first,the model of the integrated step multi-frequency shift keying(Step-MFSK)signal is built.Then we derive the its ambiguity function and autocorrelation features,and furthermore analyze the impact of carried information to the detection power of radar function.Finally,the information demodulation method is given.The simulation result verifies that the proposed signal is able to obtain ideal radar detection capacity and high rate reliable communication.From the angle of waveform design in the multi-antenna system,the author proposed the space-frequency modulation(SFM)signal.In this method,the binary sequent is mapped into a 2-demision matrix of space and frequency.The information coding is realized by the frequency modulation in the domain of antenna.For the integrated radar-communication,both the spital resoluation capability of radar sensing and transmission rate of communication data have been significiantly improved.Combing the theoretical derivation and simulation experiments result,we can conclude that the SFM signal has significance advantage on data rate while requiring more strict condition on signal to noise ratio(SNR)for accurately demodulation.Considering the high efficient power amplifier in radar system that would benefit the communication function,the integrated signal is likely to gain sufficient SNR for the demodulation.Aiming at the most serious drawbacks on the performance of detection(high range sidelobes and range sidelobe modulation)caused by communication modulation,the author proposed the mismatched filter(MMF)to realize information defusion and sidelobe suppression.At first,the invers filter(IF)that commonly used in image recovery is employed.Then the filter response is further modified to reduce the SNR loss.Finally,numerical simulations assess the effectiveness of the proposed MMF on the suppression of sidelobe and resistance of noise.Simulation results demonstrate that the proposed method enhanced the coherency between pulses after pulse compression and improved the capability of clutter cancellation.In order to avoid SNR loss caused by the process between pulse compression and increase the maximum detection range,the author proposed a modified CLEAN method to eliminate the influence of undesired range sidelobes on the air target detection.By modeling the output of matched filter as linear representation of the range responses from individual target,we utilized the undesired sidelobes characteristic as extra information in the estimation of strongest target in each loop.By considering about the sparsity of air targets,we employ the sparse representation method to estimate the complex scattering coefficient of the current strongest target.Simulation results demonstrate that the estimation accuracy of the proposed method is higher than traditional CLEAN method in the case of target occlusion.The obscured weak target achieved the same detection performance with the unobscured target,which means the influence of undesired range sidelobes on the detection performance has been totally eliminated.