Blind Integration Technology Of Weak Target Signal In Passive Radar System

The passive radar is a special bistatic radar system that uses the third-party illuminators to detecte the target without transmitting the signal itself.It can utilize the radio signals such as FM radio,television signals and mobile base stations signals etc.Due the the special structure of this system,it has many advantages that active radar system does not have.However,the always high-noise in the environment and the thirdparty signal's energy is usually weak,and the long-time integration to detect the target is needed.While the target's motion will accure the integration energy diffusion and it's necessary to compensate.This thesis will discuss the following contents as follows:1.Firstly,the system model are given.And the possibility of employing the TV satellite signal as illuminators is analyzed.Then the principle of the traditional coherent integration method of the cross ambiguity function and the long-time integration method of the equivalent pulse coherent integration are both researched and simulated in this thesis.At last,the two methods of direct signals cancellation are discussed.2.In view of the problem of compensation for range migration,we analyze the reason and consequence in presence of range migration.Then,there methods of range migration compensation are researched: The traditional interpolation,Keystone transform and RFT transform.The verification based on simulation and measured data are given at last.3.For the integration problem of multi-channel,due to the multiple transponders carried by the television satellites,it's possible to increase the system gain.The system model and the principle of the multi-channel are discussed at first.Secondly,the two methods of multi-channel integration based on Keystone transform and RFT transform are proposed respectively.The verification based on simulations are given at last.4.The compensation problem of doppler ambiguity.The probability of doppler ambiguity increases when detect the high-speed target.The reason for the appearance of doppler ambiguity is analyzed,and the definition of dopper ambiguity coefficient is given.Secondly,the compensation based on the slow-time is researched.Based on this,the compensation within the bath is proposed.And the effectiveness of the proposed methods is verified by the simulations.