High Resolution 2d Range-doppler Imaging Based On High Pulse Repetition Random Frequency Hopping Synthetic Wideband Waveform

In order to improve the performances of target detection,low probability of intercept,and anti jamming for radar imaging in the application of supersonic / hypersonic aircraft guidance,the high pulse repetition random frequency hopping synthetic wideband waveform has been used.Compared with the conventional stepped frequency synthesis wideband system,the range Doppler coupling effect of each radar echo is more complex under the system of the random frequency hopping synthesis wideband,and the relationship between the echo phase and range / velocity of targets is random and nonlinear.So it is difficult to adopt the fast imaging algorithm based on Inverse Discrete Fourier Transform(IDFT)or Inverse Fast Fourier Transform(IFFT)whether in pulse compression processing at range direction or in beam sharpening processing at Doppler direction.In addition,it is difficult to use the conventional method of fractal dimension processing in directions of range and Doppler.Therefore,it is important to develop high-quality imaging methods and fast imaging algorithms for random frequency hopping radar in supersonic / hypersonic application.Aiming at the problem of high-quality radar imaging,this paper established two simulation models of target echo and clutter signals under the situation of high pulse repetition random frequency hopping and modulations of single frequency and linear frequency.On the basis of those simulation models,this paper theoretically analyzed the special range Doppler coupling effect and its influence on radar imaging.To solve this problem,this paper proposed an imaging method based on generalized two-dimensional matched filtering and Doppl er preprocessing,in which Doppler beam sharpening was advanced to be performed with the pulse compression process in each frame,and the special range-Doppler coupling effect caused by high dynamic motion of platform and random frequency hopping in bandwi dth synthesis was well suppressed.Besides,in order to suppress the range sidelobe effect existing in the random frequency hopping synthesis wideband imaging,this paper optimized an effective two-dimensional window function,which can effectively suppress the range sidelobe effect and improve the imaging quality.Aiming at the fast imaging algorithm for the above imaging methods,this paper,for several random frequency hopping modes,combined with the data acquisition process,used the pipeline parallel processing method to optimize imaging algorithms.Theoretical analysis and simulation results show that the imaging quality of optimized imaging algorithms is the same as that of the generalized two-dimensional matched filtering method,but the processing amount is greatly reduced,which shows that the optimized algorithms can achieve a reasonable compromise between real-time and waveform randomness,thus well meet the needs of real-time imaging.In general,this paper provided a feasible technical way for high-quality and fast imaging of high repetition rate random frequency hopping synthetic wideband radar in the application of supersonic / hypersonic.