Research On Super-resolution Direction Estimation Method Based On Beam Modulation

Estimating the target’s Direction of Arrival（DOA）is the key to radar detection technology,which can guide military operations and reliable services for the civilian population.In modern radar detection,the dense target scene puts higher requirements for the direction-finding system.If the number and azimuth of the target are not accurately identified,the radar direction-finding system will be significantly damaged.However,in radar systems where array antennas cannot be used,the direction-finding resolution of the radar is limited by the antenna beam width when the antenna beam is fixed.Therefore,improving the resolution and accuracy of direction estimation is an urgent problem in radar detection.In this thesis,the mechanical scanning radar with a fixed beam shape is taken as the research object,aiming at the problem of the weak ability of integrated signal receiving of single-station radar with space,time,and frequency information,the antenna direction pattern generated by beam scanning is used to modulate echo,and the super-resolution direction estimation of multiple targets within the main beam width in the same range-bearing unit is realized.It also improves the performance under non-ideal conditions such as pulse missing or low signal-to-noise ratio.It is suitable for the case of the dense target.The main work was as follows:1.Since modern electronic reconnaissance equipment cannot receive a complete pulse signal in a complex and dense electromagnetic environment,which leads to the objective reality of pulse loss,research the cause of pulse loss and its influence on multi-target direction-finding within the same range-azimuth unit within a short period.A one-dimensional sparse super-resolution direction-finding method for stationary targets based on the Compressed Sensing（CS）theory is proposed to achieve multi-target azimuth estimation in non-holonomic pulse scenarios,and the redundant dictionaries of traditional Basis Pursuit（BP）methods are simplified.2.A two-dimensional super-resolution direction-finding method based on the minimum ₁ norm optimization criterion is proposed for moving targets with Doppler shifts between targets,which is suitable for radar search and tracking mode.The simplified redundant dictionary improves the real-time direction finding and has better requirements for pulse integrity than the BP method when the pulse is missing.The comparison of direction-finding performance verifies the feasibility of the method.3.Aiming at the problem of super-resolution direction-finding failure of the system transmitting modulated signals in the scene of low signal-to-noise ratio,a two-dimensional super-resolution direction-finding method using the Scanned Time/Angle Correlation（STAC）pulse compression principle was proposed.Angular pulse compression does not depend on either antenna aperture size or unknown motion parameters.This method improves reception gain,direction-finding resolution,and robustness.Comparing direction-finding performance in fully coherent and non-coherent scenarios supports theoretical analysis.