Research On Processing Method Of Radar Communication Shared Signal

Radar and communication are often studied as two separate systems in previous research,but they have strong similarities.The main function of radar is to detect the target,and the main function of communication is to complete the information exchange between different equipment.If the two are combined,it can not only reduce the equipment space in Shipborne,airborne and missile borne applications,realize hardware sharing and reduce electromagnetic interference,but also complement their advantages.For example,communication can rely on the pointing function of radar equipment to reduce the bit error rate.In this paper,two radar communication shared waveforms are studied.One is minimum shift keying-linear frequency modulation(MSK-LFM)radar communication shared signal which modulates communication data on single carrier LFM radar signal.The second is radar communication shared signal based on orthogonal frequency division multiplexing(OFDM).For the single carrier MSK-LFM radar communication shared signal,this paper analyzes the MSK-LFM radar communication shared signal from the aspects of signal generation,ambiguity function,detection probability,bit error rate,frequency band utilization and so on.MSK-LFM signal embodies the characteristics of MSK modulated signal and LFM signal in time domain waveform and spectrum.If it has the same energy as LFM signal,its detection probability is basically consistent with LFM signal.If the parameters are the same as the MSK modulation signal,the error rate is basically the same as of the MSK modulation signal.Some problems of MSK-LFM signal in missile borne scene are studied.Aiming at the problem of spectrum leakage of MSK-LFM signal,this paper applies the adjusted symbol arrangement method to MSK-LFM signal.This method can effectively solve the problem of spectrum leakage by compressing the symbol arrangement.Aiming at the problem of poor performance against Doppler interference,a quadratic linear iterative fast estimation algorithm based on MSK-LFM signal is proposed in this paper.The algorithm predicts the input signal offset through two linear iterative operations,and can estimate the two variables of frequency and frequency modulation rate.Compared with other estimation algorithms,this algorithm has the advantage of high real-time performance,it can be applied to Doppler estimation of MSKLFM signal.Aiming at the problem of poor performance of multipath time delay,this paper applies spread spectrum technology to MSK-LFM radar communication shared signal,which effectively reduces the impact of multipath delay on the bit error rate of shared signal.The range and velocity estimation method of MSK-LFM signal based on matched filter and Doppler filter bank is studied,which can be applied to single target and multi-target scenes.For multi carrier OFDM radar communication shared signal,this paper analyzes the radar and communication performance of binary phase shift keying(BPSK)-OFDM,complementary P4-OFDM and 16 quadrature amplitude modulation(QAM)-OFDM radar communication shared signal respectively.Aiming at the problem of high peak to average power of OFDM radar communication shared signal,amplitude limiting method and partial transmission sequence method are used to solve the problem.The applicability of the two algorithms to OFDM radar communication shared signal with different modulation modes is analyzed.The blank guard interval technology is studied to solve the problem of high sidelobe caused by cyclic prefix used in OFDM radar communication shared signal.Aiming at the low real-time performance of the existing range velocity estimation algorithms for OFDM radar communication shared signal,an estimating the signal parameters via rotational invariance technique-multiple signal classification(ESPRIT-MUSIC)algorithm based on OFDM is proposed to realize the joint fast range velocity estimation.Firstly,the radar communication shared echo signal model is transformed into a signal model similar to uniform linear array,and the time-frequency domain smoothing algorithm with weighted coefficients is used to realize decoherence processing.Then the ESPRIT algorithm is used for rough estimation,and then the MUSIC algorithm is used for fine estimation,so as to realize the joint fast range velocity estimation.The algorithm is suitable for OFDM radar communication sharing system with real-time and super-resolution requirements.