Echo-Level SAR Imaging Simulation of Wakes Excited by a Submerged Body
Abstract
:1. Introduction
2. Modeling Submerged Body Wakes in Complex Sea Surface Backgrounds
2.1. The Fluid Dynamics Model of Submerged Body Wakes
2.2. Modeling of Randomly Rough Sea Surfaces
3. Electromagnetic Modeling of Submerged Body Wakes
4. SAR Imaging Simulation of the Wake over the Sea Surface
4.1. SAR Imaging Processing of Wake over the Sea Surface Based on SAR Echo Signals
- Upon conducting the fast Fourier transform (FFT) along the range direction, the SAR raw echo signal in the frequency domain along the range dimension can be represented as:
- The SAR raw echo signal is multiplied by the range-matched filter in the range frequency domain to eliminate the second-order phase term related to fast time . The expression for the range-matched filter is:The echo signal after the range compression is expressed as:
- Changes in the instantaneous slant range lead to range cell migration, requiring correction. Range cell migration correction (RCMC) is implemented post-range compression and prior to azimuth compression. RCMC is commonly implemented within the Range-Doppler domain. The echo signal and the slant range formula in the Range-Doppler (RD) domain are obtained by azimuthal FFT and are given by:The amount of RCM to correct is given by:The Sinc interpolation operation can be used for the range cell migration correction (RCMC), Assuming the RCMC interpolation is applied accurately, the signal can be expressed as:In (19), the range envelope is now independent of azimuth frequency, indicating that the RCM has been corrected.
- An azimuth matched filter in the Range-Doppler domain is used to achieve azimuth compression and can be given byThe 2D time domain complex amplitude of compressed signal is obtained after inverse fast Fourier transform (IFFT) along the azimuth direction.The above is the process for the actual imaging for wakes over a sea surface.
4.2. Results and Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Parameter | Units | I | II |
---|---|---|---|
Depth (h) | m | h = 1.1D | |
SUBOFF velocity (U) | m/s | 3 | 5 |
Wake scene size | m × m | 30 × 40 |
Velocity (m/s) | Trough (m) | Peak (m) | Theoretical Wavelength (m) | Actual Wavelength (m) |
---|---|---|---|---|
3 | −0.11 | 0.138 | 5.764 | 5.75 |
5 | −0.161 | 0.077 | 16.01 | 17.80 |
Parameter Name | Value | Parameter Name | Value |
---|---|---|---|
Radar center frequency | 5.3 GHz | Antenna aperture | 0.5 m |
Transmitted pulse duration | 1.5 μs | Radar flight altitude | 1000 m |
Effective radar velocity | 60 m/s | Theoretical range resolution | 0.25 m |
Transmitted signal bandwidth | 600 MHz | Theoretical azimuth resolution | 0.25 m |
Beam squint angle | 0° | Average transmitted power | 1 W |
Radar incidence angle | 30° | Radar gain | 65 dB |
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Jia, Y.; Liu, S.; Liu, Y.; Zhai, L.; Gong, Y.; Zhang, X. Echo-Level SAR Imaging Simulation of Wakes Excited by a Submerged Body. Sensors 2024, 24, 1094. https://doi.org/10.3390/s24041094
Jia Y, Liu S, Liu Y, Zhai L, Gong Y, Zhang X. Echo-Level SAR Imaging Simulation of Wakes Excited by a Submerged Body. Sensors. 2024; 24(4):1094. https://doi.org/10.3390/s24041094
Chicago/Turabian StyleJia, Yan, Shuyi Liu, Yongqing Liu, Limin Zhai, Yifan Gong, and Xiangkun Zhang. 2024. "Echo-Level SAR Imaging Simulation of Wakes Excited by a Submerged Body" Sensors 24, no. 4: 1094. https://doi.org/10.3390/s24041094
APA StyleJia, Y., Liu, S., Liu, Y., Zhai, L., Gong, Y., & Zhang, X. (2024). Echo-Level SAR Imaging Simulation of Wakes Excited by a Submerged Body. Sensors, 24(4), 1094. https://doi.org/10.3390/s24041094