The Research Of GNSS Antenna Array Anti-jamming Methods Based On Subspace Projection

The transmission power of global satellite navigation satellite signal is relatively low,the satellite signal received by ground receiver is very weak,and vulnerable to all kinds of interference,so the study of navigation receiver anti-jamming technology is extremely important.This paper aims to study GNSS antenna array anti-jamming algorithm in different environments and under the condition with different parameters.Specific studies include:(1)On the basis of common GNSS receiver antenna structure model,the mathematical model of the interference signal is established.Different weighted criteria of optimal weight expressions are given,and the weighted criteria of cost function and the optimal weights are compared and analyzed;in the case of different parameters of interference,the effect of interference parameters and the number of array elements on the performance of the system is analyzed and summarized by the numerical simulation of different dimensions of spatial weight vector.(2)According to the distribution characteristics of useful signals,noise and interference of received signals,when the optimal weighted criterion and subspace projection technique is combined in this paper,anti-jamming performances of different algorithms are compared by the pattern and the output signal to noise ratio,the performance of dual subspace projection algorithm is better than simple optimal weighted algorithm.Then a new improved subspace projection algorithm is derived,which uses the equivalent array gain as the anti-jamming performance index.The interference restrain degree is introduced,the angle threshold between the weight and the interference subspace is calculated according to the restrain degree,the criteria weights that meets above condition is searched until the angle between the weight and the signal steering vector is the minimum.Finally the anti-jamming performances of improved algorithm and the subspace projection technique are compared through numerical simulation,the simulation results show that the new proposed algorithm can suppress the interference and greatly reduce the loss of useful signals.(3)The anti-jamming algorithm testing platform is built,and the anti-jamming performance is evaluated and the algorithm is tested on the basis of the platform.The platform is composed of three units,antenna unit,data acquisition unit and arithmetic unit.The analogous antenna array element generally is composed of three parts,thesignal source,the interference source,the array signal simulator.And the data acquisition unit is composed of two parts,a radio frequency module and intermediate frequency signal acquisition system.On the basis of the index system analysis of algorithm testing platform,the array signal simulator,analog front-end,and optimization of data acquisition system performance parameters,the test platform is used for the measured signal analysis,the validation of subspace projection algorithm is modified.Test results show that the validity and anti-interference ability of the proposed improved subspace projection algorithm both are superior,the proposed algorithm provides effective technical support means for the design verification of the Beidou satellite navigation system with a certain application prospect and practical value.