一種基于極坐標(biāo)格式算法的高分辨SAR成像自聚焦算法
doi: 10.11999/JEIT141131
基金項(xiàng)目:
中央高?;究蒲袠I(yè)務(wù)費(fèi)專(zhuān)項(xiàng)資金(K5051302046)和國(guó)家自然科學(xué)基金優(yōu)秀青年基金(61222108)資助課題
Autofocus Algorithm of High Resolution SAR Based on Polar Format Algorithm Processing
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摘要: 針對(duì)機(jī)載聚束合成孔徑雷達(dá)(SAR)慣導(dǎo)精度無(wú)法滿(mǎn)足高分辨SAR成像的問(wèn)題,該文提出了一種結(jié)合極坐標(biāo)格式算法(PFA)的自聚焦算法,即由粗到精的混合多階段參數(shù)化最小熵(Hybrid Multistage Parameterized Minimum Entropy, HMPME)距離單元徙動(dòng)校正方法和基于圖像對(duì)比度增強(qiáng)(Contrast Enhancement, CE)的變步長(zhǎng)迭代相位誤差校正方法。該自聚焦算法可以直接嵌入到PFA處理中,精確地補(bǔ)償了慣導(dǎo)測(cè)量精度不足引起的越距離單元徙動(dòng)(Range Cell Migration, RCM)和相位誤差,且對(duì)于低對(duì)比度、低信噪比場(chǎng)景數(shù)據(jù)有良好的聚焦性能。最后,利用仿真實(shí)驗(yàn)和實(shí)測(cè)機(jī)載聚束SAR數(shù)據(jù)驗(yàn)證了所提算法的有效性。
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關(guān)鍵詞:
- 合成孔徑雷達(dá) /
- 極坐標(biāo)格式算法 /
- 自聚焦 /
- 參數(shù)化最小熵 /
- 對(duì)比度增強(qiáng)
Abstract: Equipped with an airborne spotlight SAR, inertia navigation system can not measure the motion errors with the required accuracy for high resolution SAR imaging, which may degrade severely the quality of a SAR image. In this paper, a novel autofocus algorithm that can be directly embedded in Polar Format Algorithm (PFA) is proposed, that is, a Hybrid Multistage Parameterized Minimum Entropy (HMPME) algorithm to proceed Range Cell Migration (RCM) correction and a scaled-stepsize iterative phase correction method based on Contrast Enhancement (CE). The autofocus processing accurately compensates the effects of range cell migration and phase errors. Also, this algorithm is most robust in processing images of low contrast and low signal-to-noise ratio. Finally, simulations and experiments with real spotlight SAR data validate the effectiveness of the proposed algorithm.-
Key words:
- SAR /
- Polar Format Algorithm (PFA) /
- Autofocus /
- Parameterized minimum entropy /
- Contrast enhancement
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