Abstract
Direct quadrature modulation technology is suitable for wide-band radar signal generation. However, this method has rigorous requirements on amplitude and phase balance of the orthogonal input signals. If the requirements are not satisfied, there would be modulation errors such as image frequency and oscillator leakage that cannot be filtered. The modulation errors will therefore raise the noise floor of the range profile and reduce the dynamic range of the Synthetic Aperture Radar (SAR) image as a whole. In this paper, the wide-band In-phase/Quadrature-phase (I/Q) modulation errors are modeling analyzed, and the influence of wide-band I/Q modulation errors on SAR imaging is discussed. Furthermore, a compensation method of modulation errors is proposed, and the circuit implementation of the radar signal generation and pre-distortion is presented. The experimental results illustrate that the curves of the I/Q amplitude and phase imbalance errors are successfully extracted and the rejection of image frequency improved significantly, thus meets the requirements of the SAR imaging.
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Supported by 863 Program (2009AA12Z103) and 973 Program (2009CB72400).
Communication author: Qiao Ming, born in 1977, male, Ph.D. Candidate.
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Qiao, M., Wang, J., Zhou, L. et al. Impact of wide-band I/Q modulation errors in SAR imaging analysis and compensation method resaerch. J. Electron.(China) 30, 222–230 (2013). https://doi.org/10.1007/s11767-013-3017-2
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DOI: https://doi.org/10.1007/s11767-013-3017-2
Key words
- Direct quadrature conversion
- Amplitude and phase unbalance
- Oscillator leakage
- Image frequency suppression
- Synthetic Aperture Radar (SAR)
- Interferometric SAR (In SAR)