Main lobe jamming seriously affects the detection performance of airborne early warning radar.The joint processing of polarization-space has become an effective way to suppress the main lobe jamming.To avoid the main ...Main lobe jamming seriously affects the detection performance of airborne early warning radar.The joint processing of polarization-space has become an effective way to suppress the main lobe jamming.To avoid the main beam distortion and wave crest migration caused by the main lobe jamming in adaptive beamforming,a joint optimization algorithm based on adaptive polarization canceller(APC)and stochastic variance reduction gradient descent(SVRGD)is proposed.First,the polarization plane array structure and receiving signal model based on primary and auxiliary array cancellation are established,and an APC iterative algorithm model is constructed to calculate the optimal weight vector of the auxiliary channel.Second,based on the stochastic gradient descent principle,the variance reduction method is introduced to modify the gradient through internal and external iteration to reduce the variance of the stochastic gradient estimation,the airspace optimal weight vector is calculated and the equivalent weight vector is introduced to measure the beamforming effect.Third,by setting up a planar polarization array simulation scene,the performance of the algorithm against the interference of the main lobe and the side lobe is analyzed,and the effectiveness of the algorithm is verified under the condition of short snapshot number and certain signal to interference plus noise ratio.展开更多
Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and opera...Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and operational planning.In this paper,the Shooting and Bouncing Ray(SBR)and Uniform Theory of Diffraction(UTD)based high-frequency algorithms are used to calculate the Radar Cross Section(RCS)of helicopter,and the radar range equations are used to evaluate the stealth performance.In order to account for the effects of rotor flapping motions during actual flight,the aerodynamics model of whole helicopter is established and the attitudes and controls of helicopter at different flight states are trimmed and input into the RCS calculation module.The effects of helicopter flight speed,flying direction and operational environment on radar stealth performance are studied in focus.It is demonstrated by the results that the trimming control does have a great influence of more than 5 dB on the RCS of helicopter,and the introduction of the trim calculation brings the helicopter’s returns calculation closer to the reality.Variations in flight speed lead to the changes in the stealth performance of helicopter against Early Warning Aircraft(EWA),and the helicopter flight speed can be planned according to the operational requirements to minimize exposure distance or exposure time.Variations in flying direction mainly affect the detection properties of helicopter returns,and flying in the same direction with EWA usually gives the helicopter better low-observability than flying head-on.Variations in operational environment mainly affect the radar detection performance and the sensitivity of the detection performance to external factors;the same amount of change in some external factor causes a different amount of change in the helicopter’s detectability in different environments.展开更多
Based on the puzzle data of radar reflectivity in and around Jiangxi Province,the slope profile method and the polar coordinate method were used to display the vertical profiles of radar echoes between any two points....Based on the puzzle data of radar reflectivity in and around Jiangxi Province,the slope profile method and the polar coordinate method were used to display the vertical profiles of radar echoes between any two points.The technical route of extracting radar echo profile data by the slope method was proposed and applied to the short-term early warning platform of Jiangxi Province.A thunderstorm weather process occurring from Dongxiang to Wannian on September 23,2018 was analyzed by radar echo profiles.At present,the program has been applied to the short-term early warning platform of Jiangxi Province based on B/S architecture.The automatic drawing and display of radar echo profiles of any two points is practical for forecasters to quickly and effectively track short-term strong convection weather.展开更多
Using minute rainfall data of automatic ground station and a variety of products from new generation Doppler weather radar in Wuchuan, the characteristics of a short-time heavy precipitation process on April 23, 2022 ...Using minute rainfall data of automatic ground station and a variety of products from new generation Doppler weather radar in Wuchuan, the characteristics of a short-time heavy precipitation process on April 23, 2022 were analyzed. The results showed that the appearance of differential reflectivity(ZDR) column and big-value zone of high-elevation ZDR had better indication on short-term heavy rainfall process in Shichao station. Ice phase process played a very important role in particle growth. The storm tracking information product can predict the path of the storm 15 min in advance. The storm stayed and moved less or even turned back to more than two to three scanning volumes in one place, indicating the occurrence of short-term heavy rainfall. One-hour accumulated precipitation(OHP) had a good effect on the estimation of continuous precipitation in a large area where the hourly rainfall exceeded 50 mm for more than two stations. It had the ability to estimate short-term heavy precipitation in areas lacking automatic stations.展开更多
基金supported by the Aviation Science Foundation of China(20175596020)。
文摘Main lobe jamming seriously affects the detection performance of airborne early warning radar.The joint processing of polarization-space has become an effective way to suppress the main lobe jamming.To avoid the main beam distortion and wave crest migration caused by the main lobe jamming in adaptive beamforming,a joint optimization algorithm based on adaptive polarization canceller(APC)and stochastic variance reduction gradient descent(SVRGD)is proposed.First,the polarization plane array structure and receiving signal model based on primary and auxiliary array cancellation are established,and an APC iterative algorithm model is constructed to calculate the optimal weight vector of the auxiliary channel.Second,based on the stochastic gradient descent principle,the variance reduction method is introduced to modify the gradient through internal and external iteration to reduce the variance of the stochastic gradient estimation,the airspace optimal weight vector is calculated and the equivalent weight vector is introduced to measure the beamforming effect.Third,by setting up a planar polarization array simulation scene,the performance of the algorithm against the interference of the main lobe and the side lobe is analyzed,and the effectiveness of the algorithm is verified under the condition of short snapshot number and certain signal to interference plus noise ratio.
基金supported by a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD).
文摘Airborne pulse Doppler radar is a key threat to the military helicopter,and assessing the stealth performance of helicopter against airborne early warning radar is helpful to the helicopter’s stealth design and operational planning.In this paper,the Shooting and Bouncing Ray(SBR)and Uniform Theory of Diffraction(UTD)based high-frequency algorithms are used to calculate the Radar Cross Section(RCS)of helicopter,and the radar range equations are used to evaluate the stealth performance.In order to account for the effects of rotor flapping motions during actual flight,the aerodynamics model of whole helicopter is established and the attitudes and controls of helicopter at different flight states are trimmed and input into the RCS calculation module.The effects of helicopter flight speed,flying direction and operational environment on radar stealth performance are studied in focus.It is demonstrated by the results that the trimming control does have a great influence of more than 5 dB on the RCS of helicopter,and the introduction of the trim calculation brings the helicopter’s returns calculation closer to the reality.Variations in flight speed lead to the changes in the stealth performance of helicopter against Early Warning Aircraft(EWA),and the helicopter flight speed can be planned according to the operational requirements to minimize exposure distance or exposure time.Variations in flying direction mainly affect the detection properties of helicopter returns,and flying in the same direction with EWA usually gives the helicopter better low-observability than flying head-on.Variations in operational environment mainly affect the radar detection performance and the sensitivity of the detection performance to external factors;the same amount of change in some external factor causes a different amount of change in the helicopter’s detectability in different environments.
基金Supported by the Project of Jiangxi Meteorological Bureau and Jiangxi Department of Science and Technology for Training of Young Talents in Jiangxi Province in 2017"Research on the Improvement of Cross Correlation Tracking Method(COTREC) Based on Continuous Equations"Key Research and Development Plan Project of Jiangxi Province,China(20171BBG70004)
文摘Based on the puzzle data of radar reflectivity in and around Jiangxi Province,the slope profile method and the polar coordinate method were used to display the vertical profiles of radar echoes between any two points.The technical route of extracting radar echo profile data by the slope method was proposed and applied to the short-term early warning platform of Jiangxi Province.A thunderstorm weather process occurring from Dongxiang to Wannian on September 23,2018 was analyzed by radar echo profiles.At present,the program has been applied to the short-term early warning platform of Jiangxi Province based on B/S architecture.The automatic drawing and display of radar echo profiles of any two points is practical for forecasters to quickly and effectively track short-term strong convection weather.
文摘Using minute rainfall data of automatic ground station and a variety of products from new generation Doppler weather radar in Wuchuan, the characteristics of a short-time heavy precipitation process on April 23, 2022 were analyzed. The results showed that the appearance of differential reflectivity(ZDR) column and big-value zone of high-elevation ZDR had better indication on short-term heavy rainfall process in Shichao station. Ice phase process played a very important role in particle growth. The storm tracking information product can predict the path of the storm 15 min in advance. The storm stayed and moved less or even turned back to more than two to three scanning volumes in one place, indicating the occurrence of short-term heavy rainfall. One-hour accumulated precipitation(OHP) had a good effect on the estimation of continuous precipitation in a large area where the hourly rainfall exceeded 50 mm for more than two stations. It had the ability to estimate short-term heavy precipitation in areas lacking automatic stations.
