Research On Adaptive Interference Suppression In Satellite Navigation Receiver

It is acknowledged that the increasingly complex environment around us and therapid development of interference technology have posed a severe challenge to theprecision applications of satellite navigation. Interference has been a serious threat tothe satellite navigation accuracy, availability, continuity and integrity. Anti-jammingtechnology of satellite navigation system has become an important guarantee for thesuccessful application. As a core technology of satellite navigation terminal, manycountries begin to research and develop the anti-jamming satellite navigation receiverbased on adaptive array. Anti-jamming satellite navigation receiver can not onlyeliminate the interference, multipath and noise impact on the receiver, maximum outputsignal-to-interference-plus-noise ratio (SINR), but also recover the amplitude and phaseof transmitted signal correctly to effectively achieve distance measurement andpositioning. Moreover, it should have a fast convergence of adaptive anti-jamming.Thus, this dissertation researches mainly on adaptive interference suppressionmethods for satellite navigation receiver, which contain fast interference suppressionmethod, blind interference suppression, multipath mitigation and multiple targettracking method. The main content of this dissertation are as follows:1. An adaptive anti-jamming method based on Householder reflection is proposedfor GPS receiver. Adaptive generalized sidelobe canceller (GSC) often employsleast-mean-square for weight adaptation, but it cannot satisfy the requirement ofreal-time adaptive interference suppression for GPS receiver due to the slowconvergence. Since the convergence behavior of the LMS algorithm is highly dependenton the eigenvalue spreads of covariance matrix of the blocking matrix output, theblocking matrix based on Householder reflection in lower path can not only blockdesired signal completely, but also accelerate convergence rate of LMS algorithm andmaximize the output SINR. Furthermore, it can improve the rapid anti-jammingperformance of the GPS receiver. The proposed method converges faster than cascadedcolumn of differencing (CCD)-based method, and has less computational complexitythan the SVD method.2. A two-dimensional adaptive interference suppression method is proposed basedon Kalman filter. First, in order to block the desired signal completely, Householderreflection is employed to build two-dimensional GSC blocking matrix. The adaptiveGSC weight vector in lower path of two-dimensional array can be updated by Kalmanfiltering. The method can effectively mitigate interference in two-dimensional space. Compared with Householder reflection based GSC-LMS method, Householder basedGSC-Kalman has higher convergence rate and larger output SINR. So it can improvethe anti-jamming performance of GPS receiver.3. A novel blind interference suppression method is proposed for the GPS receiver.The process of positioning requires at least pseudo range measurements to four satellites.However, strong interference, even if intentional, makes the receiver unable to obtainmeasurements from the multiple GPS satellite. Combined with the knowledge of eachdesired satellite’s C/A code, a multi-target adaptive array based on minimum meansquare error (MMSE) algorithm is employed for interference suppression of multiplesatellites. The proposed method can mitigate the jammers beyond the direction ofdesired satellites without the location knowledge of desired satellites and estimation ofthe steering vector. The method can not only effectively suppress various interferencesbut also estimate accurately the angle of arrival information of the multiple desiredsatellite signals. Moreover, the number of desired satellite is not limited by the numberof antennas.4. A novel adaptive multipath suppression method is proposed for GPS receiver.Since C/A code signal is duplicated during a navigation data symbol, extract the desiredsignal and multipath through strong self-coherence between chip-rate samples separatedby the integer multiple of the spreading gain in the low SNR. Then forward andbackward spatial smoothing method is employed to estimate the azimuth of the GPSsignal. Finally, construct multiple GSC adaptive arrays for each sub-array divided byspatial smoothing to achieve multipath mitigation effectively. The proposed method caneffectively mitigate multipath and reduce the influence of the multipath on codetracking delay-locked loop (DLL). It can make the receiver obtain more precisesynchronization time while avoiding the influence of multipath, so it has a veryeffective significance for GPS positioning. In addition, the high-precision orientationmeasurement of the desired satellite can be estimated in multipath environment.5. This chapter proposes a new multi-target direction of arrival (DOA) trackingmethod based on fast data projection method and Kalman filter. When there existsmoving jammers around GPS receiver, DOA should be estimated and tracked to reducethe effection of interference. First，we employ fast data projection method which is arobust adaptive subspace tracking method with lower computational cost. Then eachtarget’s time-varying DOA can be obtained from the new subspace by New-ton method.Finally, multiple targets’ DOA can be predicted accurately by Kalman filter. The tracking capability of the proposed algorithm is demonstrated by computer simulationsin scenarios involving targets with crossing trajectories. The proposed method has fastspeed, high precision and can avoid data association.