High Frame Rate ViSAR Based on OAM Beams: Imaging Model and Imaging Algorithm.
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| Title: | High Frame Rate ViSAR Based on OAM Beams: Imaging Model and Imaging Algorithm. |
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| Authors: | Li, Xiaopeng1 (AUTHOR), Xu, Liying2 (AUTHOR), Mao, Yongfei3 (AUTHOR), Li, Weisong4,5,6 (AUTHOR), Li, Yinwei4,5,6,7 (AUTHOR) liyw@usst.edu.cn, Wang, Hongqiang6,8 (AUTHOR), Zhu, Yiming4,5,7 (AUTHOR) |
| Source: | Remote Sensing. Jan2026, Vol. 18 Issue 2, p294. 30p. |
| Subjects: | Synthetic apertures, Electromagnetic waves, Vector beams, Imaging systems, Image reconstruction algorithms |
| Abstract: | Highlights: Regarding the fixed-mode design, this paper introduces a frame-varying time-varying mode design method to achieve extended azimuth bandwidth. Distinct from traditional azimuth bandwidth enhancement methods, this imaging model increases the azimuth bandwidth by raising the azimuth chirp rate, thereby improving the video SAR frame rate. What are the main findings? Based on the characteristics of vortex electromagnetic waves, a dual-beam center imaging method is proposed. This effectively mitigates the impact of the energy hollow region of vortex electromagnetic waves on imaging and improves the Taylor expansion approximation error in the time-varying mode de-sign. Corresponding imaging algorithms are redesigned based on the improved im-aging model and mode design. Considering the space-variant nature of the new chirp rate, corresponding matched filters and vortex term elimination methods are designed to achieve focused imaging. What are the implications of the main findings? An innovative video SAR time-varying imaging framework has been constructed, opening a new path for improving frame rates. By introducing "frame-varying time-varying mode design," a novel approach to bandwidth ex-tension is proposed, establishing a new imaging model. This model successfully unifies azimuth bandwidth enhancement with frame rate improvement, providing a new theoretical foundation and implementation scheme for high-frame-rate video SAR imaging. Key challenges in vortex wave video SAR imaging have been resolved. Addressing the inherent energy "hollow" problem of vortex electromagnetic waves, the proposed "dual-beam center" imaging method cleverly circumvents its effects while improving model approximation errors. On this basis, a complete and self-consistent imaging algorithm has been designed, ultimately ensuring high-quality, high-resolution focused imaging. High frame rate imaging of synthetic aperture radar (SAR), also known as video SAR (ViSAR), has attracted extensive research in recent years. When ViSAR system parameters are fixed, there is a technical trade-off between high frame rates and high resolution. In traditional ViSAR, the frame rate is usually increased by increasing the carrier frequency to increase the azimuth modulation frequency and reducing the synthetic aperture time. This paper attempts to propose a strip non-overlapping mode ViSAR based on Orbital Angular Momentum (OAM) beams, which uses the topological charge of vortex electromagnetic wave (VEW) to improve the azimuth modulation frequency, to improve the frame rate. By introducing the concept of VEW frame splitting, a corresponding time-varying topological charge mode is designed for ViSAR imaging. This design successfully introduces an additional azimuth modulation frequency while maintaining the original imaging resolution, thus significantly improving the frame rate performance of the ViSAR system. However, the Bessel function term in VEW causes amplitude modulation in the echo signal, while the additional frequency modulation causes the traditional matching filter to fail. To address these problems, an improved Range-Doppler algorithm (RDA) is proposed in this paper. By employing the range cell center approximation method, the negative effect of the Bessel function on imaging is reduced effectively. Furthermore, for the introduction of tuning frequency, the azimuth matched filter is specially improved, which effectively prevents the defocusing issues caused by the mismatch of tuning frequency. Finally, the computer simulation results prove that the ViSAR system and imaging algorithm based on VEW can effectively improve the frame rate of ViSAR and maintain the imaging resolution, which provides a research direction for the development of ViSAR technology. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Highlights: Regarding the fixed-mode design, this paper introduces a frame-varying time-varying mode design method to achieve extended azimuth bandwidth. Distinct from traditional azimuth bandwidth enhancement methods, this imaging model increases the azimuth bandwidth by raising the azimuth chirp rate, thereby improving the video SAR frame rate. What are the main findings? Based on the characteristics of vortex electromagnetic waves, a dual-beam center imaging method is proposed. This effectively mitigates the impact of the energy hollow region of vortex electromagnetic waves on imaging and improves the Taylor expansion approximation error in the time-varying mode de-sign. Corresponding imaging algorithms are redesigned based on the improved im-aging model and mode design. Considering the space-variant nature of the new chirp rate, corresponding matched filters and vortex term elimination methods are designed to achieve focused imaging. What are the implications of the main findings? An innovative video SAR time-varying imaging framework has been constructed, opening a new path for improving frame rates. By introducing "frame-varying time-varying mode design," a novel approach to bandwidth ex-tension is proposed, establishing a new imaging model. This model successfully unifies azimuth bandwidth enhancement with frame rate improvement, providing a new theoretical foundation and implementation scheme for high-frame-rate video SAR imaging. Key challenges in vortex wave video SAR imaging have been resolved. Addressing the inherent energy "hollow" problem of vortex electromagnetic waves, the proposed "dual-beam center" imaging method cleverly circumvents its effects while improving model approximation errors. On this basis, a complete and self-consistent imaging algorithm has been designed, ultimately ensuring high-quality, high-resolution focused imaging. High frame rate imaging of synthetic aperture radar (SAR), also known as video SAR (ViSAR), has attracted extensive research in recent years. When ViSAR system parameters are fixed, there is a technical trade-off between high frame rates and high resolution. In traditional ViSAR, the frame rate is usually increased by increasing the carrier frequency to increase the azimuth modulation frequency and reducing the synthetic aperture time. This paper attempts to propose a strip non-overlapping mode ViSAR based on Orbital Angular Momentum (OAM) beams, which uses the topological charge of vortex electromagnetic wave (VEW) to improve the azimuth modulation frequency, to improve the frame rate. By introducing the concept of VEW frame splitting, a corresponding time-varying topological charge mode is designed for ViSAR imaging. This design successfully introduces an additional azimuth modulation frequency while maintaining the original imaging resolution, thus significantly improving the frame rate performance of the ViSAR system. However, the Bessel function term in VEW causes amplitude modulation in the echo signal, while the additional frequency modulation causes the traditional matching filter to fail. To address these problems, an improved Range-Doppler algorithm (RDA) is proposed in this paper. By employing the range cell center approximation method, the negative effect of the Bessel function on imaging is reduced effectively. Furthermore, for the introduction of tuning frequency, the azimuth matched filter is specially improved, which effectively prevents the defocusing issues caused by the mismatch of tuning frequency. Finally, the computer simulation results prove that the ViSAR system and imaging algorithm based on VEW can effectively improve the frame rate of ViSAR and maintain the imaging resolution, which provides a research direction for the development of ViSAR technology. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 20724292 |
| DOI: | 10.3390/rs18020294 |
