Research On Anti-jamming Methods Of GNSS Based On Sparse Array

The global navigation satellite system(GNSS),which has applied in military and civilian fields widely and successfully,could provide high-precision and all-weather location,speed and timing services on a global scale,and it has the vital significance for national security and economic development.At the same time,with the electromagnetic environment becoming more and more complexity,satellite signal will be subject to various kinds of interference during the propagation,which will bring about the receiver being unable to locate accurately.Therefore,in order to make the receiver work normally even when jammed,anti-jamming measures are constantly emerging.The current mainstream anti-jamming measure at present is the satellite navigation receiver based on uniform linear array,but its anti-jamming freedoms is limited by the number of array elements.With the sparse arrays,an enlarged array aperture and more array degrees of freedom(DOFs)can be achieved under the same array elements as the uniform linear array,so the influence of interference on the receiver is limited to the most extent,thus making it possible to use fewer physical elements and lower hardware costs.In this paper,the anti-jamming method of satellite navigation based on sparse array is studied.Firstly,the mathematical model of uniform and sparse array receiving signals is established under ideal conditions,and the characteristics of DOFs enhancement brought by sparse array are analyzed.The receiving and processing of the incident signal data by the array antenna is discussed.What's more,the array antenna patterns with their performances are compared.Secondly,the basic principle of adaptive array anti-jamming is expounded,and the optimal criteria of several beam-forming are analyzed.On this foundation,several classical adaptive beam-forming algorithms are given.Then,the principle of traditional multi-source direction of arrival(DOA)estimation algorithm is introduced.At the same time,nested array and co-prime array are used as the objects.The multi-source DOA estimation method based on sparse array is studied.Based on spatial smoothing technology,the virtual domain subspace technology is applied to the sparse array.The virtual domain subspace joint anti-jamming algorithm based on sparse array is proposed.By constructing virtual uniform linear array,the DOA of the interference source is estimated,and the interferences is suppressed by the adaptive beam-forming technique.This algorithm is valid when the number of interferences is more than that of array elements,and it has excellent ant-jamming performance when the directions of interferences are close to each other.Finally,through introducing compressed sensing theory into the DOA estimation of the interference source,the compressed sensing DOA estimation model of the co-prime array is established.The DOA estimation and suppression method based on the compressed sensing is proposed with applying the prime and sparse characteristics of the co-prime array.The method reconstructs the inference source by the algorithms of convex optimization and OMP respectively,then uses the subspace projection technique to suppress the estimated interference source.It eliminates the feature decomposition of the array covariance matrix.Without losing the array aperture,it still has perfect performance of interference estimation and suppression under low snapshot.