摘要(英) |
Synthetic Aperture Radar (SAR) is a radar system that is often used to perform telemetry tasks. This radar system synthesizes a large aperture to improve image resolution by moving the radar antenna. In order to pursue better resolution, this paper mainly implements the imaging algorithms and Doppler centroid estimation commonly used. In terms of imaging algorithm, we compare different secondary range compression method and proposed compression method. We will use the range Doppler algorithm with different secondary range compression method to compare the imaging performance and the computational complexity with different secondary range compression method. In addition, we will also introduce the chirp scaling algorithm, and compare the imaging performance with the range Doppler algorithm. In the range cell migration correction, the range Doppler algorithm mainly uses the interpolator to correct the position of sampling point in the range and azimuth direction point by point, while the chirp scaling algorithm correct the position of sampling points with the same Doppler frequency by phase multiplication. The parameters of phase multiplication change with time, therefore, we have to evaluate the imaging performance and the computational complexity when we select the imaging algorithm. In the part of the Doppler centroid estimation algorithm, first of all, we will check the correctness of the Doppler centroid estimation in different scenarios and in different signal-to-noise, and then, we can determine whether the Doppler centroid estimation results can be used for imaging algorithms by analyzing the characteristics of the received signal. |
論文目次 |
摘要 i
Abstract ii
目錄 iii
表目錄 v
圖目錄 vii
第一章 緒論 1
1.1 研究動機 1
1.2 研究方法 1
1.3 論文組織 2
第二章 掃描式合成孔徑雷達系統 3
2.1 掃描式合成孔徑雷達回波訊號 3
2.1.1 發射波訊號形式 4
2.1.2 回波訊號形式 6
2.2 凱澤窗(Kaiser window) 11
2.3 內插器 14
2.4 規格簡介 16
2.5 用於模擬之場景假設 22
第三章 合成孔徑雷達成像演算法 27
3.1 基本距離都普勒演算法(Basic Range Doppler Algorithm, Basic RDA) 27
3.1.1 距離方向壓縮 28
3.1.2 距離偏移修正 28
3.1.3 方位方向壓縮 30
3.2 二次距離壓縮(Secondary Range Compression, SRC) 31
3.2.1 理想二次距離壓縮(SRC Option 1) 32
3.2.2 距離簡化之二次距離壓縮(SRC Option 2) 33
3.2.3 距離與都普勒頻率簡化之二次距離壓縮(SRC Option 3) 34
3.2.4 距離區塊獨立之二次距離壓縮(SRC Segment) 35
3.2.5 二次距離壓縮法之比較 36
3.3 三階二次距離壓縮(Third-Order Secondary Range Compression, TRC) 40
3.4 鳥鳴刻度演算法(Chirp Scaling Algorithm, CSA) 46
3.4.1 鳥鳴刻度對不同距離之偏移修正 48
3.4.2 距離方向壓縮與二次距離壓縮與二次距離壓縮 50
3.4.3 方位方向壓縮與殘餘相位修正 52
3.4.4 加入三階之二次距離壓縮 53
3.5 由演算法效能決定接收器之接收時間與計算複雜度比較 56
3.5.1 由演算法效能決定接收器之接收時間 56
3.5.2 計算複雜度比較 57
第四章 都普勒質心估測 60
4.1 都普勒質心 60
4.2 都普勒基頻質心估測 60
4.2.1 以回波能量估測都普勒基頻質心 60
4.2.2 以回波相位估測都普勒基頻質心 64
4.3 都普勒歧義值估測 70
4.3.1 波長差異演算法(The Wavelength Diversity Algorithm, WDA) 70
4.3.2 多視互相關演算法(Multilook Cross Correlation Algorithm, MLCC) 75
4.3.3 多視互乘頻率演算法(Multilook Beat Frequency Algorithm, MLBF) 77
4.4 以場景特性評斷都普勒估測之結果 80
4.4.1 回波的訊號雜訊比 94
4.4.2 回波的波形失真度 96
4.4.3 回波的對比度 101
4.4.4 評斷都普勒估測結果之程序 103
第五章 結論 104
參考文獻 105
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參考文獻 |
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