基于时频分析的频率步进ISAR成像

Time Frequency Analysis-Based Stepped frequency ISAR Imaging

频率步进是逆合成孔径雷达 (inversesyntheticapertureradar,ISAR)采用的重要波形形式。本文从数学角度分析了频率步进ISAR成像原理 ,介绍了传统距离—多普勒算法及基于时频分析的频率步进ISAR成像处理流程。最后对机动目标成像进行了仿真分析 ,结果表明对于机动目标采用时频分析方法能够降低成像模糊 ,从而获得高质量成像。

Step frequency (SF) waveform, which is convenient for synthesizing Ul tra-Wide Band (UWB) signal while still keeps narrow instant band width, is used widely in inverse synthetic aperture radar imaging (ISAR).In this paper, the imaging principle of step frequency ISAR was analyzed from mathematic aspect by modeling a radar and two scatterers firstly. Following that, the flow chart of signal processing for imaging based on traditional Range-Doppler algorithm and Time-Frequency analysis method were introduced separately. Finally, the authors simulated return signal of a maneuvering target by carrying out a target model with nine scatters and assuming that it is accelerating rotating around with its center. Through comparing images obtained by traditional Range-Doppler algorithm and Time-Frequency Analysis method, the results show that time frequency-based imaging methods are more sophisticated than Range-Doppler algorithm for imaging maneuvering targets.