45732 radar MIMO OFDM.rar_target tracking_target detection_matlab例程

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<div id="pf2" class="pf w3 hb" data-page-no="2"><div class="pc pc2 w3 hb"><img class="bi x0 y0 w1 hc" alt="" src="https://static.pudn.com/prod/directory_preview_static/625a145f92dc900e62da5352/bg2.jpg"><div class="t m0 x18 hd y1c ff4 fs7 fc3 sc0 ls0 ws0">Chapter 3</div><div class="t m0 x19 he y1d ff4 fs8 fc3 sc0 ls0 ws0">Multi-Frequency Image Fusion Based on MIMO UWB</div><div class="t m0 x19 he y1e ff4 fs8 fc3 sc0 ls0 ws0">OFDM Synthetic Aperture Radar</div><div class="t m0 x19 hd y1f ff5 fs7 fc3 sc0 ls0 ws0">Md Anowar Hossain, Ibrahim Elshafiey and</div><div class="t m0 x19 hd y20 ff5 fs7 fc3 sc0 ls0 ws0">Majeed A. S. Alkanhal</div><div class="t m0 x19 hf y21 ff5 fs9 fc3 sc0 ls0 ws0">Additional information is available at the end of the chapter</div><div class="t m0 x19 hf y22 ff5 fs9 fc3 sc0 ls0 ws0">http://dx.doi.org/10.5772/56943</div><div class="t m0 x19 h10 y23 ff6 fs7 fc3 sc0 ls0 ws0">1. Introduction</div><div class="t m0 x19 h11 y24 ff7 fsa fc3 sc0 ls0 ws0">The principle idea behind synthetic aperture radar (SAR) stems from the desire for high-</div><div class="t m0 x19 h11 y25 ff7 fsa fc3 sc0 ls0 ws0">resolution images. SAR transmits signal at spaced intervals called pulse repetition interval</div><div class="t m0 x19 h11 y26 ff7 fsa fc3 sc0 ls0 ws0">(PRI). The responses at each PRI are collected and processed to reconstruct a radar image of</div><div class="t m0 x19 h11 y27 ff7 fsa fc3 sc0 ls0 ws0">the terrain [1]. In general, high-resolution SAR images in range domain are generated using</div><div class="t m0 x19 h11 y28 ff7 fsa fc3 sc0 ls0 ws0">ultra-wideband (UWB) waveforms as radar transmitted pulse [2]. UWB pulses (500 MHz</div><div class="t m0 x19 h11 y29 ff7 fsa fc3 sc0 ls0 ws0">bandwidth and above) can enhance the range resolution considerably. UWB technology has</div><div class="t m0 x19 h11 y2a ff7 fsa fc3 sc0 ls0 ws0">dual advantages: good capacity of penetration and high-resolution target detection in range</div><div class="t m0 x19 h11 y2b ff7 fsa fc3 sc0 ls0 ws0">domain for radar applications [3].</div><div class="t m0 x19 h11 y2c ff7 fsa fc3 sc0 ls0 ws0">Orthogonal frequency division multiplexing (OFDM), a modulation scheme commonly</div><div class="t m0 x19 h11 y2d ff7 fsa fc3 sc0 ls0 ws0">utilized in commercial communications, shows a great potential for use in forming radar</div><div class="t m0 x19 h11 y2e ff7 fsa fc3 sc0 ls0 ws0">waveforms. An OFDM signal is comprised of several orthogonal subcarriers, which are</div><div class="t m0 x19 h11 y2f ff7 fsa fc3 sc0 ls0 ws0">simultaneously emitted over a single transmission path. Each subcarrier occupies a small slice</div><div class="t m0 x19 h11 y30 ff7 fsa fc3 sc0 ls0 ws0">of the entire signal bandwidth [4]. Technology advances helped in increasing the sampling</div><div class="t m0 x19 h11 y31 ff7 fsa fc3 sc0 ls0 ws0">speed capabilities, allowing accurate generation of UWB-OFDM waveforms. This results in a</div><div class="t m0 x19 h11 y32 ff7 fsa fc3 sc0 ls0 ws0">diverse signal that is capable of high-resolution imaging. While OFDM has been elaborately</div><div class="t m0 x19 h11 y33 ff7 fsa fc3 sc0 ls0 ws0">studied and commercialized in the digital communication field, it has not yet been widely</div><div class="t m0 x19 h11 y34 ff7 fsa fc3 sc0 ls0 ws0">studied by the radar scientific community apart from a few efforts [5-7]. The advantages of</div><div class="t m0 x19 h11 y35 ff7 fsa fc3 sc0 ls0 ws0">using OFDM in radar applications include: (a) Transceiver system is based on digital imple‐</div><div class="t m0 x19 h11 y36 ff7 fsa fc3 sc0 ls0 ws0">mentation using relatively inexpensive components (b) Ease of narrowband interference</div><div class="t m0 x19 h11 y37 ff7 fsa fc3 sc0 ls0 ws0">mitigation (c) High-resolution in UWB scale and good multi-path potential (d) Same architec‐</div><div class="t m0 x19 h11 y38 ff7 fsa fc3 sc0 ls0 ws0">ture can be used to transmit large amounts of data in real time; and (e) Flexibility in pulse</div><div class="t m0 x19 h11 y39 ff7 fsa fc3 sc0 ls0 ws0">shaping using different subcarrier compositions.</div><div class="t m0 x1a h12 y3a ff5 fsb fc3 sc0 ls0 ws0">© 2013 Hossain et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons</div><div class="t m0 x1a h12 y3b ff5 fsb fc3 sc0 ls0 ws0">Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,</div><div class="t m0 x1a h12 y3c ff5 fsb fc3 sc0 ls0 ws0">distribution, and reproduction in any medium, provided the original work is properly cited.</div></div><div class="pi" data-data='{"ctm":[1.991701,0.000000,0.000000,1.991701,0.000000,0.000000]}'></div></div>

<div id="pf3" class="pf w3 hb" data-page-no="3"><div class="pc pc3 w3 hb"><img class="bi x0 y0 w1 hc" alt="" src="https://static.pudn.com/prod/directory_preview_static/625a145f92dc900e62da5352/bg3.jpg"><div class="t m0 x19 h11 y3d ff7 fsa fc3 sc0 ls0 ws0">Although SAR is a well-known remote sensing application which obtains high-resolution in</div><div class="t m0 x19 h11 y3e ff7 fsa fc3 sc0 ls0 ws0">range domain by transmitting wide-band waveform and high-resolution in azimuth domain</div><div class="t m0 x19 h11 y3f ff7 fsa fc3 sc0 ls0 ws0">by utilizing the relative motion between the target and the radar platform, current single</div><div class="t m0 x19 h11 y40 ff7 fsa fc3 sc0 ls0 ws0">antenna SAR is not able to provide some remote sensing performances, such as simultaneously</div><div class="t m0 x19 h11 y41 ff7 fsa fc3 sc0 ls0 ws0">high-resolution and wide-swath imaging. Multiple-Input Multiple-Output (MIMO) SAR</div><div class="t m0 x19 h11 y42 ff7 fsa fc3 sc0 ls0 ws0">provides a solution to resolve these problems and provides following advantages compared</div><div class="t m0 x19 h11 y43 ff7 fsa fc3 sc0 ls0 ws0">to traditional SAR: diversity in viewing angles on a particular target to improve identifiability,</div><div class="t m0 x19 h11 y44 ff7 fsa fc3 sc0 ls0 ws0">increased azimuth resolution or decreased pulse repetition frequency (PRF) which results in</div><div class="t m0 x19 h11 y45 ff7 fsa fc3 sc0 ls0 ws0">wider swath. Due to the larger number of degrees-of-freedom of a MIMO system, enhanced</div><div class="t m0 x19 h11 y46 ff7 fsa fc3 sc0 ls0 ws0">resolution can be achieved by coherently processing of multiple waveforms at multiple</div><div class="t m0 x19 h11 y47 ff7 fsa fc3 sc0 ls0 ws0">receivers simultaneously.</div><div class="t m0 x19 h11 y48 ff7 fsa fc3 sc0 ls0 ws0">Several research works have been reported in recent years to overcome the trade-off between</div><div class="t m0 x19 h11 y49 ff7 fsa fc3 sc0 ls0 ws0">wide-swath and azimuth resolution in conventional SAR system [8]. However, MIMO SAR</div><div class="t m0 x19 h11 y4a ff7 fsa fc3 sc0 ls0 ws0">systems are only investigated by generalizing the theoretical modeling of MIMO communi‐</div><div class="t m0 x19 h11 y4b ff7 fsa fc3 sc0 ls0 ws0">cation systems and discussed recently in radar communities [9 and 10]. The configuration of</div><div class="t m0 x19 h11 y4c ff7 fsa fc3 sc0 ls0 ws0">the proposed MIMO-SAR system in this chapter is considered as two co-located transmitters</div><div class="t m0 x19 h11 y4d ff7 fsa fc3 sc0 ls0 ws0">and two receivers along with image fusion technique.</div><div class="t m0 x19 h11 y4e ff7 fsa fc3 sc0 ls0 ws0">In remote sensing applications, the increasing availability of spaceborne sensor gives a</div><div class="t m0 x19 h11 y4f ff7 fsa fc3 sc0 ls0 ws0">motivation to utilize image fusion algorithms. Several situations in image processing require</div><div class="t m0 x19 h11 y50 ff7 fsa fc3 sc0 ls0 ws0">high spatial and high spectral resolution in a single image. Image fusion is the process of</div><div class="t m0 x19 h11 y51 ff7 fsa fc3 sc0 ls0 ws0">combining relevant information from two or more images into a single image. The resulting</div><div class="t m0 x19 h11 y52 ff7 fsa fc3 sc0 ls0 ws0">image will be more informative than any of the input images [11].</div><div class="t m0 x19 h11 y53 ff7 fsa fc3 sc0 ls0 ws0">The structure of the chapter is as follows. UWB-OFDM pulse shaping for MIMO SAR is</div><div class="t m0 x19 h11 y54 ff7 fsa fc3 sc0 ls0 ws0">described in section 2, while the comparison of auto-correlation and cross-correlation of</div><div class="t m0 x19 h11 y55 ff7 fsa fc3 sc0 ls0 ws0">different pulses in radar perspective is presented in section 3. Detailed analysis of MIMO wide-</div><div class="t m0 x19 h11 y56 ff7 fsa fc3 sc0 ls0 ws0">swath SAR system and its functionality is discussed in section 4. MIMO wide-swath SAR</div><div class="t m0 x19 h11 y57 ff7 fsa fc3 sc0 ls0 ws0">imaging results based on UWB-OFDM waveforms are presented in section 5. Section 6 presents</div><div class="t m0 x19 h11 y58 ff7 fsa fc3 sc0 ls0 ws0">the optimized SAR image based on image fusion technique. Final conclusions are provided in</div><div class="t m0 x19 h11 y59 ff7 fsa fc3 sc0 ls0 ws0">section 7.</div><div class="t m0 x19 h10 y5a ff6 fs7 fc3 sc0 ls0 ws0">2. MIMO UWB OFDM signal generation</div><div class="t m0 x19 h11 y5b ff7 fsa fc3 sc0 ls0 ws0">A widely studied approach in MIMO architecture involves the transmission of orthogonal</div><div class="t m0 x19 h11 y5c ff7 fsa fc3 sc0 ls0 ws0">signals from different antennas. This makes it possible to separate the reflected signals from</div><div class="t m0 x19 h11 y5d ff7 fsa fc3 sc0 ls0 ws0">the target arriving at the receiver. In particular, we develop a procedure to design the optimal</div><div class="t m0 x19 h11 y5e ff7 fsa fc3 sc0 ls0 ws0">waveform that ensures orthogonality by imposing the rules shown in Table 1. The key to our</div><div class="t m0 x19 h11 y5f ff7 fsa fc3 sc0 ls0 ws0">approach is to use a model for the received radar signals that explicitly includes the transmitted</div><div class="t m0 x19 h11 y60 ff7 fsa fc3 sc0 ls0 ws0">waveforms. To achieve lower cross-correlation between transmitted pulses with a common</div><div class="t m0 x19 h11 y61 ff7 fsa fc3 sc0 ls0 ws0">bandwidth for the same range resolution, OFDM frequency-domain sample vector for N</div><div class="t m0 x19 h11 y62 ff7 fsa fc3 sc0 ls0 ws0">subcarriers is generated using the sequences shown in Table 1. The sequence in Table 1</div><div class="t m0 x19 h11 y63 ff7 fsa fc3 sc0 ls0 ws0">generates the orthogonal signals based on the placement of 1’s and 0’s. We observe that in each</div><div class="t m0 x19 h13 y64 ff5 fsc fc3 sc0 ls0 ws0">New Advances in Image Fusion</div><div class="t m0 x1b h13 y65 ff5 fsc fc3 sc0 ls0 ws0">38</div></div><div class="pi" data-data='{"ctm":[1.991701,0.000000,0.000000,1.991701,0.000000,0.000000]}'></div></div>

<div id="pf4" class="pf w3 hb" data-page-no="4"><div class="pc pc4 w3 hb"><img class="bi x0 y0 w1 hc" alt="" src="https://static.pudn.com/prod/directory_preview_static/625a145f92dc900e62da5352/bg4.jpg"><div class="t m0 x19 h11 y3d ff7 fsa fc3 sc0 ls0 ws0">column, if we consider a 1, the other elements are 0’s and the next column is filled with all 0’s</div><div class="t m0 x19 h11 y66 ff7 fsa fc3 sc0 ls0 ws0">to prevent over-sampling. The spectrum of an OFDM signal is shown in Figure 1 where the</div><div class="t m0 x19 h11 y67 ff7 fsa fc3 sc0 ls0 ws0">width of the main-lobe depends on the duration of the pulse. In digital implementation of an</div><div class="t m0 x19 h11 y68 ff7 fsa fc3 sc0 ls0 ws0">OFDM signal, the pulse duration is related to the number of subcarriers. As the number of</div><div class="t m0 x19 h11 y69 ff7 fsa fc3 sc0 ls0 ws0">subcarrier increases, the duration of the pulse increases.</div><div class="t m0 x1c h13 y6a ff5 fsc fc3 sc0 ls0 ws0">1 2 3 - - - - - - - - - - - - N</div><div class="t m0 x1d h13 y6b ff5 fsc fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x1e h14 y6c ff5 fsd fc3 sc0 ls0 ws0">ω1</div><div class="t m0 x1c h13 y6b ff5 fsc fc3 sc0 ls0 ws0">1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0</div><div class="t m0 x1d h13 y6d ff5 fsc fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x1e h14 y6e ff5 fsd fc3 sc0 ls0 ws0">ω2</div><div class="t m0 x1c h13 y6d ff5 fsc fc3 sc0 ls0 ws0">0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0</div><div class="t m0 x1d h13 y6f ff5 fsc fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x1e h14 y70 ff5 fsd fc3 sc0 ls0 ws0">ω3</div><div class="t m0 x1c h13 y6f ff5 fsc fc3 sc0 ls0 ws0">0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0</div><div class="t m0 x1d h13 y71 ff5 fsc fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x1e h14 y72 ff5 fsd fc3 sc0 ls0 ws0">ω4</div><div class="t m0 x1c h13 y71 ff5 fsc fc3 sc0 ls0 ws0">0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0</div><div class="t m0 x19 h13 y73 ff4 fsc fc3 sc0 ls0 ws0">Table 1. OFDM frequency-domain sample vector generation</div><div class="t m0 x19 h13 y74 ff4 fsc fc3 sc0 ls0 ws0">Figure 1. OFDM signal spectrum</div><div class="t m0 x19 h11 y75 ff7 fsa fc3 sc0 ls0 ws0">As an example, an OFDM signal is generated according to the scheme shown in Figure 2 by</div><div class="t m0 x19 h11 y76 ff7 fsa fc3 sc0 ls0 ws0">spreading the digital frequency domain vector shown in Table 1 and the modulation symbol</div><div class="t m0 x19 h11 y77 ff7 fsa fc3 sc0 ls0 ws0">from random integer generator. The order of modulation (M) is chosen as 4 for QPSK. Inverse</div><div class="t m0 x19 h11 y78 ff7 fsa fc3 sc0 ls0 ws0">Fast Fourier Transform (IFFT) is then applied to obtain the discrete time domain OFDM signal</div><div class="t m0 x19 h11 y79 ff7 fsa fc3 sc0 ls0 ws0">and finally Hanning window is imposed to minimize the side-lobes. The time-domain OFDM</div><div class="t m0 x19 h11 y7a ff7 fsa fc3 sc0 ls0 ws0">signal is given as</div><div class="t m0 x1f h13 y64 ff5 fsc fc3 sc0 ls0 ws0">Multi-Frequency Image Fusion Based on MIMO UWB OFDM Synthetic Aperture Radar</div><div class="t m0 x20 h13 y7b ff5 fsc fc3 sc0 ls0 ws0">http://dx.doi.org/10.5772/56943</div><div class="t m0 x21 h13 y65 ff5 fsc fc3 sc0 ls0 ws0">39</div></div><div class="pi" data-data='{"ctm":[1.991701,0.000000,0.000000,1.991701,0.000000,0.000000]}'></div></div>

<div id="pf5" class="pf w3 hb" data-page-no="5"><div class="pc pc5 w3 hb"><img class="bi x0 y0 w1 hc" alt="" src="https://static.pudn.com/prod/directory_preview_static/625a145f92dc900e62da5352/bg5.jpg"><div class="t m0 x22 h11 y7c ff7 fsa fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x23 h15 y7d ff7 fse fc3 sc0 ls0 ws0">txi</div><div class="t m0 x24 h11 y7e ff7 fsa fc3 sc0 ls0 ws0">(</div><div class="t m0 x25 h11 y7c ff7 fsa fc3 sc0 ls0 ws0">t</div><div class="t m0 x26 h11 y7e ff7 fsa fc3 sc0 ls0 ws0">)</div><div class="t m0 x27 h11 y7c ff7 fsa fc3 sc0 ls0 ws0">=Ϝ</div><div class="t m0 x28 h15 y7f ff7 fse fc3 sc0 ls0 ws0">-1</div><div class="t m0 x29 h11 y7c ff7 fsa fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x2a h15 y7d ff7 fse fc3 sc0 ls0 ws0">ωi</div><div class="t m0 x2b h11 y7c ff7 fsa fc3 sc0 ls0 ws0"> w</div><div class="t m0 x2c h11 y7e ff7 fsa fc3 sc0 ls0 ws0">(</div><div class="t m0 x2d h11 y7c ff7 fsa fc3 sc0 ls0 ws0">n</div><div class="t m0 x2e h11 y7e ff7 fsa fc3 sc0 ls0 ws0">)</div><div class="t m0 x2f h11 y7c ff7 fsa fc3 sc0 ls0 ws0"> i = 1,2, ⋯ 4 (1)</div><div class="t m0 x19 h11 y80 ff7 fsa fc3 sc0 ls0 ws0">where, Hanning window w</div><div class="t m0 x23 h11 y81 ff7 fsa fc3 sc0 ls0 ws0">(</div><div class="t m0 x30 h16 y80 ff8 fsa fc3 sc0 ls0 ws0">n</div><div class="t m0 x6 h11 y81 ff7 fsa fc3 sc0 ls0 ws0">)</div><div class="t m0 x31 h11 y80 ff7 fsa fc3 sc0 ls0 ws0">=0.5</div><div class="t m3 x28 h17 y82 ff7 fsf fc3 sc0 ls0 ws0">{</div><div class="t m0 x32 h11 y80 ff7 fsa fc3 sc0 ls0 ws0">1 - cos</div><div class="t m3 x2b h17 y82 ff7 fsf fc3 sc0 ls0 ws0">(</div><div class="t m0 x33 h15 y83 ff7 fse fc3 sc0 ls0 ws0">2πn</div><div class="t m0 x34 h18 y84 ff8 fse fc3 sc0 ls0 ws0">N</div><div class="t m3 x2e h17 y82 ff7 fsf fc3 sc0 ls0 ws0">)}</div><div class="t m0 x35 h11 y80 ff7 fsa fc3 sc0 ls0 ws0">, 0 ≤ n ≤ N - 1 and N is the number of subcar‐</div><div class="t m0 x19 h11 y85 ff7 fsa fc3 sc0 ls0 ws0">riers. The term </div><div class="t m0 x17 h16 y86 ff8 fsa fc3 sc0 ls0 ws0">Ψ</div><div class="t m0 x36 h18 y87 ff8 fse fc3 sc0 ls0 ws0">ωi</div><div class="t m0 x16 h11 y86 ff7 fsa fc3 sc0 ls0 ws0"> </div><div class="t m0 x37 h11 y85 ff7 fsa fc3 sc0 ls0 ws0"> denotes the spreading sequences for i</div><div class="t m0 x38 h19 y88 ff7 fs10 fc3 sc0 ls0 ws0">th</div><div class="t m0 x39 h11 y85 ff7 fsa fc3 sc0 ls0 ws0"> sub-pulses. Each antenna transmits</div><div class="t m0 x19 h11 y89 ff7 fsa fc3 sc0 ls0 ws0">two sub-pulses simultaneously.</div><div class="t m0 x19 h11 y8a ff7 fsa fc3 sc0 ls0 ws0">UWB-OFDM waveforms are generated using the following parameters: number of OFDM</div><div class="t m0 x19 h11 y8b ff7 fsa fc3 sc0 ls0 ws0">subcarriers, N = 256, sampling time, Δt</div><div class="t m0 xf h1a y8c ff8 fs10 fc3 sc0 ls0 ws0">s</div><div class="t m0 x2a h11 y8b ff7 fsa fc3 sc0 ls0 ws0"> = 1ns results in baseband bandwidth, B</div><div class="t m0 x3a h1a y8c ff8 fs10 fc3 sc0 ls0 ws0">0</div><div class="t m0 x3b h11 y8b ff7 fsa fc3 sc0 ls0 ws0"> = 1/2Δt</div><div class="t m0 x3c h1a y8c ff8 fs10 fc3 sc0 ls0 ws0">s</div><div class="t m0 x3d h11 y8b ff7 fsa fc3 sc0 ls0 ws0"> = 500</div><div class="t m0 x19 h11 y8d ff7 fsa fc3 sc0 ls0 ws0">MHz, dividing by a factor of two to satisfy Nyquist criterion. UWB-OFDM waveform in</div><div class="t m0 x19 h11 y8e ff7 fsa fc3 sc0 ls0 ws0">frequency domain and time domain is shown in Figure 3 and Figure 4 respectively. We can</div><div class="t m0 x19 h11 y8f ff7 fsa fc3 sc0 ls0 ws0">observe that the Hanning window reasonably minimizes side-lobes which in turns improve</div><div class="t m0 x19 h11 y90 ff7 fsa fc3 sc0 ls0 ws0">the auto-correlation function (ACF) and cross-correlation function (CCF) of time-domain</div><div class="t m0 x19 h11 y91 ff7 fsa fc3 sc0 ls0 ws0">OFDM waveforms as shown in Figure 5 and Figure 6, respectively.</div><div class="t m0 x19 h13 y92 ff4 fsc fc3 sc0 ls0 ws0">Figure 2. OFDM signal generator</div><div class="t m0 x19 h13 y93 ff4 fsc fc3 sc0 ls0 ws0">Figure 3. UWB-OFDM waveform in frequency-domain (a) before windowing (b) after windowing</div><div class="t m0 x19 h13 y64 ff5 fsc fc3 sc0 ls0 ws0">New Advances in Image Fusion</div><div class="t m0 x1b h13 y65 ff5 fsc fc3 sc0 ls0 ws0">40</div></div><div class="pi" data-data='{"ctm":[1.991701,0.000000,0.000000,1.991701,0.000000,0.000000]}'></div></div>