Space-Based Early Warning Radar Detection For Maneuvering Target

The difficulties of maneuvering target detection by space-based early warning radar are the low signal to noise ratio and the high relative speed, even the high acceleration between the satellite platform and targets. This dissertation is focused on the research on space-based early warning radar's maneuvering target detection. The key contributions are:1. On the basis of air-borne early warning radar, this paper analyzes the difficulties of maneuvering target detection by space-based early warning radar on the satellite platform, and the reasons for range migration and Doppler ambiguity. Theoretical analysis and experiments had verified that range migration and Doppler ambiguity have adverse effects of pulse accumulation.2. A joint method of improved the CRT and Keystone transform is proposed to improve solve range migration correction. The method is based on double pulse repetition frequency. Firstly,the Space-borne echo returns in range frequency and pulse time domain are aligned in pulse time-domain by Keystone transform after the pulse compression,thus the echo pulse train is cohered.The estimate of Doppler ambiguity degree can be obtained according to the improved the CRT and the accurate velocity estimation.3. A method of moving target detection based on Hough transformation is presented, which is used to detect high speed moving dim targets under the satellite platform. Because of insensitivity to partial loss and strong robustness, Hough transform is used to suppress noise ,detect target with constant velocity and obtain a accurate speed estimates, and the error is less than 3‰.4. A method of maneuvering target detection based on randomized Hough transformation is presented, which is used to detect dim targets with a higher relative acceleration and relative velocity under the satellite platform and obtain a accurate speed and acceleration estimates. The velocity estimation error is less than 3 %, the acceleration estimation error less than 6%.5. A method of maneuvering target detection is proposed for space-based early warning radar, which firstly uses the generalized Keystone transform to remove of the impact of acceleration on the pulse accumulation, secondly uses randomized Hough transform to estimates the acceleration and compensate phase of the signal, thirdly use the generalized Keystone transform again to eliminate the impact of speed on the pulse accumulation, finally complete pulse accumulation for targets with unknown velocity and acceleration. It is shown that the method can still correctly detect the target and get accurate estimates of speed and acceleration, and the error does not exceed 2% at the signal to noise ratio beyond -13.28dB.