Study On GNSS Antenna Arrays Anti-jamming Algorithm And Performance Evaluation Key Techniques

GNSS, represented by GPS, has been extensively and successfully applied to manyfields, while it has exposed serious difficulty of poor antijamming performance. How toimprove the system antijamming performance to meet the the requirements ofNAVWAR under the live-fire circumstance is a research focus in GNSS field. Latestdevelopments of NAVWAR bring forwad a new challege on the antijammingalgorithms and performance evaluation. On the background of GNSS antijam antennaarray, this dissertation has researched the performance evaluation and test techniques interms of accuracy, comprehensiveness, efficiency. And with the goal of practicability ofantijamming receivers, the dissertation has researched the antijamming algorithims ofnew signal modulation such as BOC signals. Four aspects will be carried out as follows:(1) Aiming at the problem of inaccuracy of result of performance evaluation bytraditional method, the dissertation constructed the accurate model of array processingtransfer function, analyzed the deficiency of narrowband hypothesis and array gainindex, put forwad an innovative performance evaluation based on the despread spectrumperformance with accurate wideband model. The new method used equivalent arraygain as index, reduced the evaluation errors from up to10dB to about1dB.(2) Aiming at the problem of inaccuracy of performance evaluation by traditionalmethod, the dissertation inverstigated the two aspects of statistic performanceevaluation: the judge criterion of single signal availability and overall signal availabilitywith respect to navigation requirements. The dissertation introduced the equivalentarray gain as the judge criterion of receiver availability, and extended the averageavailability of single signal to average solution probability and navigation serviceavailability. Additionally, the dissertation improved the test method of averageavailability; the new method decreased the amount of signal&interference scenariosgreatly utilizing the symmetry of angle between signal subspace and jammer subspace.Numrical calculation results indicated that the new method decreased the scenariosabout80%.(3) The performance improvement of given signal&interference scenarios is thefoundation of statistical performance enhancement. Aiming at increasing the equivalentarray gain, the thesis studied the problem of MSINR applied to BOC signal; proposed anovel method based on the average of the two subbands according to the BOC signal’sspectrum. The new algorithm with4antennas and15taps increased the equivalent arraygain about2.5dB and average availability about20%, decerased the ACF distortion ofarray processing. Furthermore, the weighted subbands MSINR criterion is introduced.(4) Aiming at fixing the problem of inaccurate judgement of strong signals andjammers with traditional frequency domain jammer suppression method, the dissertation put forward a novel jammer judgement method without judge threshold. To maximizethe despread spectrum performance, the new method judge the jammer spectrumaccording to the contribution on the equivalent carrier to noise ratio of received signalspectrum at different frequencies. In the multiple scenes combined with the weak signal,strong signal and jammer, the new method could make the accurate judgement, with theloss lower than0.5dB compared to the theoretic limit performance.At last, the research work of this dissertation and its application were summarizedand reviewd; and the future research to be carried out was also presented. The resultshave been used to index demonstration of NAVWAR, developing antijamming receiverand anti-jam performance measure scheme design of Chinese satellite navigationsystem.