Multi-Target Detection Method Based On Chaotic Shape-Forming Filter And Its Performance Analysis

Chaotic signal has the special characteristics like a wide frequency spectrum,internal randomness,non-periodicity,sensitive initial values,high complexity,easy generation,and difficult long-term prediction,which demonstrate great potential in the fields of communication and radar and attracts wide concerns.Especially in recent years,some new progress has been made in the application of chaotic shape-forming filter(CSF)in signal processing,which proves that some new characteristics of CSF are beneficial to communication signal processing.This thesis studies the multi-target range-velocity measurement method and the integrated scheme design of radar-communication systems based on CSF,and analyzes the performance of the proposed scheme.(1)For traditional radar signals,for example,the linear frequency modulation(LFM)signal,there is a range-velocity coupling problem.The length of the Barker code cannot be chosen arbitrarily and its ambiguity function has high sidelobes around the central peak.When the echo signal passes through the matched filter,there may be no prominent peaks in the filter output signal,so it is not suitable for the scene of multi-target simultaneous ranging-velocity measurement.A multi-target simultaneous range-velocity measurement method is proposed based on CSF to deal with the problems existing in traditional radar signals.The ambiguity function of the detection signal is an ideal "pushpin" shape with low sidelobes and no rangeDoppler coupling problem.Since only the bipolar discrete signal corresponding to the detection waveform is stored at the radar receiver,the storage space occupied is small,and the process is inexpensive to implement.It is verified by simulation that the proposed scheme has good detection performance.To deal with the multi-user interference problem in the actual environment,it is veri fied by simulation that the initial value sensitivity of the chaotic signal can suppress the multi-user interference without designing complex signal processing methods.(2)The traditional integrated radar-communication systems are mainly divided into two categories depending on the waveform design methods:one category is the integrated signal based on the traditional radar waveform,which introduces the modulation to the linear frequency modulation signal to transmit information simultaneously.In order to avoid the effect on the detection function,only the simple modulation methods can be used,which makes the communication rate rather low.The other category is the integrated signal based on the communication waveform.The large peak-to-average ratio of the orthogonal frequency division multiplexing(OFDM)leads to a large dynamic range of the detection system,and the existing signal processing system is difficult to ensure the integrity of the signal.Using chaotic signal generated by the CSF as the integrated radar-communication waveform can meet the needs of radar and communication at the same time.The integrated design scheme of radarcommunication systems based on CSF is proposed in this thesis,at the radar receiver,the integrated signal generated by CSF has an ideal "pushpin" ambiguity function,with low sidelobes,narrow main lobes,and concentrated energy,which renders higher detection accuracy than the linear frequency modulation-binary phase shift keying(LFM-BPSK)signal.When the signal-tonoise ratio is OdB,other conditions are the same,the approximate ratio of the distance root mean square error(RMSE)between the radar communication integrated signal generated by the CSF and the LFM-BPSK signal is 1/13,and the approximate ratio of the velocity RMSE is 1/1.36.At the communication receiver,the low priority communication rate of this scheme is the same as that of the LFM-BPSK scheme.When the Eb/N0 is 12dB in the multipath channel,the low priority bit error rate(BER)of this scheme is 0.03644%,and the BER of the LFM-BPSK scheme is 1.268%,the BER performance of low priority is significantly better than that of the LFMBPSK scheme.While the proposed scheme can transmit additional high priority information,which make the date rate is higher than LFM-BPSK.Finally,the communication and radar detection performance of the integrated radar-communication signal based on CSF is analyzed by simulation,and the results verify the superiority of the proposed integrated scheme.