Research On Radio Astronomy Anti-navigation Signal Interference

Since the 1930 s,the observing frequency of radio astronomy has expanded to 1MHz-1000 GHz with the development of the radio telescopes' resolution.However it is the same with the radio career,and its greater demand of the radio spectrum affects the radio astronomy observation.The fact is that more radio frequency interference(RFI)is coming from the Earth,and the most common one is the navigation signal.It is always disturbed by GPS L2 signal when observing the 21 cm spectral line using the radio telescope,based on this research background,the paper using an auxiliary antenna discussed two usual questions of the radio astronomy,the limitation of anti-interference performance evaluation indicator and the effect of existing fractional delay in the main and auxiliary antenna on anti-jamming methods.Aiming at the limitation of evaluation indicators,here deduced two evaluation indicators: the signal power attenuation Gs and the interference power suppression GI,by which we can easily obtain the variation of the power of radio astronomy signal and navigation interference,and evaluate the anti-interference performance accurately.About the fractional delay between main and auxiliary antenna,we designed two types of fractional delay FIR filter with high precision reaching a 10-7 order,using the optimization method and the AP window respectively.Finally,we proposed an adaptive filter method based on delay matched,and verified the suppression performance of the LMS algorithm and the LMS algorithm based on delay matched by multiple simulations,and it turned out that the later one has better anti-interference performance,meanwhile,verified the indicators' utility.