Research On Passive Localization Of Multi-subband External Radiation Source

The radar positioning system based on external radiation source has gradually become a research hotspot due to its advantage of concealment and the continuous expansion of the available radiation sources types.In the passive positioning of external radiation sources,the types of signal that can be used include broadcast signal,digital TV signal,communication or radar signal,etc.A common method using broadband signals is dividing them into the multiple subband signals that satisfy the narrow-band conditions.For external radiation source signals with multi-subband characteristics,better parameter estimation performance can be obtained by jointly processing multiple subband signals,such as frequency hopping signals.Focusing on the passive localization of external radiation sources,this thesis studies the TDOA(Time Difference of Arrival,TDOA)estimation method and the DPD(Direct Position Determination,DPD)methods based on multi-subband utilization.The main contents of the thesis are as follows:Firstly,under the condition of the external radiation source detecting,the signal model under the condition of multi-subband signal is constructed.The proposed algorithm and the CRLB(Cramer-Rao Lower Bound,CRLB)of TDOA estimation and position estimation under the condition of single subband is also presented.Then,the Lower bound and approaches for the complex condition of the multi-subband signal are derived.The simulation verifies that the proposed methods can achieve the corresponding CRLB under the mild noise condition,considering the influence of the frequency interval between the subband signals on the TDOA estimation,the interpolation is used in the frequency interval to integrate the known information into the new subband signal of interpolation.In the simulation,it is verified that the signal generated from interpolation can obtain better performance of the TDOA estimation.Then,to alleviate the error accumulation problem of the two-step positioning method,the DPD based on coherence is deduced.Considering that the signal-to-noise ratio of the direct path and the target reflection path in the external radiation source scenario have obvious gap,the cost function is optimized,and the CRLB level performance is verified by the simulation.