In this paper, an inverse synthetic aperture radar (ISAR) image transform method is proposed by utilizing the unique property of joint intra-pulse and inter-pulse periodic-coded phase modulation. By extending the periodic-coded phase modulation to the azimuth dimension, the multiple false targets spread along both the range and azimuth directions, then makes the target of interest (TOI) indistinguishable thus get effectively protected. On this basis, the image transform properties and parameter design principles are further discussed. Finally, both numerical and measured Yak-42 aircraft data simulations are conducted to demonstrate the validity of the proposed method.

In this letter, a synthetic aperture radar (SAR) image transform method is proposed using the periodic-coded phase modulation. By modulating the intercepted radar signal with the periodic-coded phase pulse, multiple false targets can be formed along the range direction in the radar image. Then the target of interest (TOI) can get protected by the deception jamming effect. On this basis, the jamming property and parameter design principles are further discussed. Finally, the mini-SAR data experiment indicates multiple false targets approximately from 15 to 30 dB higher than the low-level background are generated in the SAR image, then demonstrates the validity of the proposed image transform method.

Compared with the amplitude modulation of conventional interrupted sampling repeater jamming (ISRJ), the image feature control method based on phase modulation exhibits greater energy efficiency and, therefore, has received wide attention recently. In this paper, an Inverse Synthetic Aperture Radar (ISAR) image feature suppression method based on arbitrary phase encoding (APE) is proposed. The parameter design criterion is further analyzed. Through the nonperiodic segmented coding and modulation of the imaging signal in fast and slow time domains, the modulated signal produces a two-dimensional suppression region with uniform energy distribution in the ISAR image. Simulations via the measured Yak-42 aircraft data have verified the effectiveness of the proposed method for target feature control. Compared to binary phase modulation jamming, the APE method with a phase modulation accuracy of 1 degree can achieve the same jamming effect while reducing the jamming power requirement by 3 dB. By optimizing with the proposed method, the image entropy of the interfered image increases by 1.1 to 1.5 compared to the original image.