Study On Active ECCM In Multiple-radar Systems

The survival pressure of monostatic radar system decreases gradually with the development of active jamming.Benefitting from the unique construction features,multiple-radar system can extract abundant resources from space domain and time domain,which provides a new way for active jamming countermeasure.The differences between real targets and false targets can be found by information fusion technology,which can be utilized to improve the anti-jamming capability of the multiple-radar system.Supported by the pre-research scientific research “XXXX ECCM techniques” of the 13 th Five-Year Plan,the author studied the active jamming ECCM methods for multiple-radar system based on data fusion and signal fusion.The main contents include: Study on the method against the deception-false-target jamming based on data fusion with isomerous multiple-radar system.For the isomerous multiple-radar system consists of 2D radar system and 3D radar system,the distance and azimuth between target and 2D radar is estimated by making use of the measurement of 3D radar,by comparing the estimated value and the measurement of 2D radar,the false-target is discriminated by using chi-square statistics.For the isomerous multiple-radar system consists of active radar system and passive radar system,the trace point in active radar and passive radar is firstly associated,in this step,false target with long deception range can be eliminated.The measured values in passive radar passing the trace correlation is used for track initiation.Track correlation test is further used to eliminate the false target which have formed stable track.Study on the mainlobe jamming suppression method on signal fusion with multiple-radar system.The difference in spatial scattering properties between target echoes and jamming signal is utilized for jamming suppression.After the jamming signals have been aligned,a steering vector can be found of jamming signals and target echoes.In a multiple-radar system,the energy of the jamming signals will be concentrated in a single-rank subspace whereas the energy of the target echoes will be scattered throughout the signal space of the node array.The projection matrix of the noise subspace is obtained by decomposing the covariance matrix trained by the time domain sampling data.The jamming signals can be effectively suppressed through the noise subspace projection operation.A general likelihood ratio test detector for the subspace projection operation is derived.Because the projection operation is not only for the jamming signals but also for the target echoed,this method will not lead the loss of JNR,it can also reduce the impact of interference leakage on target detection by reducing the dimension of noise subspace.Furthermore,the geometric parameters of the multiple-radar system and the amplitude and phase errors between the radars are not needed in the method,which is capable of strong adaptive ability to the internal structure of the array.Study on the polarimetric multiple-radar system for discriminating between radar targets and deception jamming.The existing deception ECCMs based on signal fusion ignore the difference on polarization scattering characteristics.In the process of transmitting radar signal,the polarization parameters of jammer are brought in target echoes,causing a linear relationship between the elements in the polarization scattering coefficient of jamming signal.For target echoes,there is no linear relationship between elements in the polarization scattering coefficient due to different observe views.Based on this difference,a two-stage detection/discrimination algorithm is proposed.The targets and jamming are detected in the first stage from noise background.Then,a discriminator based on the generalized likelihood ratio test is designed.The anti-jamming performance of the algorithm can be significantly improved by optimizing the spatial and polarization diversities of the system.This method avoids the complex correlation test and not needs the amplitude information of the target echoes,so it is still effective when the jammer decorrelates the amplitude of the jamming signal or when the target echoes are not completely independent.The simulation results show that the anti-jamming performance of this method is better than the existing signal fusion method.Study on the deception ECCM based on power allocation with multiple-radar system.Making use of its superior joint detection ability,the multiple-radar system can discriminate deception jamming through the estimation of deceptive parameters of deception jamming in the process of joint detection and parameter estimation.When discriminating the target by the parameter estimation information,equal power allocation method unable to give full play to its anti-jamming ability.In this chapter,a method of power allocation approach for antideception jamming in multiple-radar is proposed for the requirement of making full use of the limited resource.Firstly,the Cramer-Rao lower bound(CRLB)of the deception range is derived according to the parameter estimation model of netted radars under the deception jamming,and a theoretical discrimination probability of deception targets is then given.Secondly,a power allocation approach is derived to maximize the discrimination probability of deception targets.This method ensures that more power resources can be allocated to the transmitting stations with large difference observe view and low path loss,which can effectively improve the anti-jamming probability under the constraint of limited system resources.