786 research outputs found

    Design and Implementation of a FPGA and DSP Based MIMO Radar Imaging System

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    The work presented in this paper is aimed at the implementation of a real-time multiple-input multiple-output (MIMO) imaging radar used for area surveillance. In this radar, the equivalent virtual array method and time-division technique are applied to make 16 virtual elements synthesized from the MIMO antenna array. The chirp signal generater is based on a combination of direct digital synthesizer (DDS) and phase locked loop (PLL). A signal conditioning circuit is used to deal with the coupling effect within the array. The signal processing platform is based on an efficient field programmable gates array (FPGA) and digital signal processor (DSP) pipeline where a robust beamforming imaging algorithm is running on. The radar system was evaluated through a real field experiment. Imaging capability and real-time performance shown in the results demonstrate the practical feasibility of the implementation

    FMCW rail-mounted SAR: Porting spotlight SAR imaging from MATLAB to FPGA

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    In this work, a low-cost laptop-based radar platform derived from the MIT open courseware has been implemented. It can perform ranging, Doppler measurement and SAR imaging using MATLAB as the processor. In this work, porting the signal processing algorithms onto a FPGA platform will be addressed as well as differences between results obtained using MATLAB and those obtained using the FPGA platform. The target FPGA platforms were a Virtex6 DSP kit and Spartan3A starter kit, the latter was also low-cost to further reduce the cost for students to access radar technology

    The Fundamentals of Radar with Applications to Autonomous Vehicles

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    Radar systems can be extremely useful for applications in autonomous vehicles. This paper seeks to show how radar systems function and how they can apply to improve autonomous vehicles. First, the basics of radar systems are presented to introduce the basic terminology involved with radar. Then, the topic of phased arrays is presented because of their application to autonomous vehicles. The topic of digital signal processing is also discussed because of its importance for all modern radar systems. Finally, examples of radar systems based on the presented knowledge are discussed to illustrate the effectiveness of radar systems in autonomous vehicles

    ์‹ค์‹œ๊ฐ„ ๊ทผ๊ฑฐ๋ฆฌ ์˜์ƒํ™”๋ฅผ ์œ„ํ•œ MIMO ์—ญํ•ฉ์„ฑ ๊ฐœ๊ตฌ ๋ ˆ์ด๋” ์‹œ์Šคํ…œ

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    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ) -- ์„œ์šธ๋Œ€ํ•™๊ต๋Œ€ํ•™์› : ๊ณต๊ณผ๋Œ€ํ•™ ์ „๊ธฐยท์ •๋ณด๊ณตํ•™๋ถ€, 2022. 8. ๋‚จ์ƒ์šฑ.Microwave and millimeter wave (micro/mmW) imaging systems have advantages over other imaging systems in that they have penetration properties over non-metallic structures and non-ionization. However, these systems are commercially applicable in limited areas. Depending on the quality and size of the images, a system can be expensive and images cannot be provided in real-time. To overcome the challenges of the current micro/mmW imaging system, it is critical to suggest a new system concept and prove its potential benefits and hazards by demonstrating the testbed. This dissertation presents Ku1DMIC, a wide-band micro/mmW imaging system using Ku-band and 1D-MIMO array, which can overcome the challenges above. For cost-effective 3D imaging capabilities, Ku1DMIC uses 1D-MIMO array configuration and inverse synthetic aperture radar (ISAR) technique. At the same time, Ku1DMIC supports real-time data acquisition through a system-level design of a seamless interface with frequency modulated continuous wave (FMCW) radar. To show the feasibility of 3D imaging with Ku1DMIC and its real-time capabilities, an accelerated imaging algorithm, 1D-MIMO-ISAR RSA, is proposed and demonstrated. The detailed contributions of the dissertation are as follows. First, this dissertation presents Ku1DMIC โ€“ a Ku-band MIMO frequency-modulated continuous-wave (FMCW) radar experimental platform with real-time 2D near-field imaging capabilities. The proposed system uses Ku-band to cover the wider illumination area given the limited number of antennas and uses a fast ramp and wide-band FMCW waveform for rapid radar data acquisition while providing high-resolution images. The key design aspect behind the platform is stability, reconfigurability, and real-time capabilities, which allows investigating the exploration of the systemโ€™s strengths and weaknesses. To satisfy the design aspect, a digitally assisted platform is proposed and realized based on an AMD-Xilinx UltraScale+ Radio Frequency System on Chip (RFSoC). The experimental investigation for real-time 2D imaging has proved the ability of video-rate imaging at around 60 frames per second. Second, a waveform digital pre-distortion (DPD) method and calibration method are proposed to enhance the image quality. Even if a clean FMCW waveform is generated with the aid of the optimized waveform generator, the signal will inevitably suffer from distortion, especially in the RF subsystem of the platform. In near-field imaging applications, the waveform DPD is not effective at suppressing distortion in wide-band FMCW radar systems. To solve this issue, the LO-DPD architecture and binary search based DPD algorithm are proposed to make the waveform DPD effective in Ku1DMIC. Furthermore, an image-domain optimization correction method is proposed to compensate for the remaining errors that cannot be eliminated by the waveform DPD. For robustness to various unwanted signals such as noise and clutter signals, two regularized least squares problems are applied and compared: the generalized Tikhonov regularization and the total variation (TV) regularization. Through various 2D imaging experiments, it is confirmed that both methods can enhance the image quality by reducing the sidelobe level. Lastly, the research is conducted to realize real-time 3D imaging by applying the ISAR technique to Ku1DMIC. The realization of real-time 3D imaging using 1D-MIMO array configuration is impactful in that this configuration can significantly reduce the costs of the 3D imaging system and enable imaging of moving objects. To this end, the signal model for the 1D-MIMO-ISAR configuration is presented, and then the 1D-MIMO-ISAR range stacking algorithm (RSA) is proposed to accelerate the imaging reconstruction process. The proposed 1D-MIMO-ISAR RSA can reconstruct images within hundreds of milliseconds while maintaining almost the same image quality as the back-projection algorithm, bringing potential use for real-time 3D imaging. It also describes strategies for setting ROI, considering the real-world situations in which objects enter and exit the field of view, and allocating GPU memory. Extensive simulations and experiments have demonstrated the feasibility and potential benefits of 1D-MIMO-IASR configuration and 1D-MIMO-ISAR RSA.๋งˆ์ดํฌ๋กœํŒŒ ๋ฐ ๋ฐ€๋ฆฌ๋ฏธํ„ฐํŒŒ(micro/mmW) ์˜์ƒํ™” ์‹œ์Šคํ…œ์€ ๋น„๊ธˆ์† ๊ตฌ์กฐ ๋ฐ ๋น„์ด์˜จํ™”์— ๋น„ํ•ด ์นจํˆฌ ํŠน์„ฑ์ด ์žˆ๋‹ค๋Š” ์ ์—์„œ ๋‹ค๋ฅธ ์ด๋ฏธ์ง• ์‹œ์Šคํ…œ์— ๋น„ํ•ด ์žฅ์ ์ด ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์ด๋Ÿฌํ•œ ์‹œ์Šคํ…œ์€ ์ œํ•œ๋œ ์˜์—ญ์—์„œ๋งŒ ์ƒ์—…์ ์œผ๋กœ ์ ์šฉ๋˜๊ณ  ์žˆ๋‹ค. ์ด๋ฏธ์ง€์˜ ํ’ˆ์งˆ๊ณผ ํฌ๊ธฐ์— ๋”ฐ๋ผ ์‹œ์Šคํ…œ์ด ๋งค์šฐ ๊ณ ๊ฐ€์ผ ์ˆ˜ ์žˆ์œผ๋ฉฐ ์ด๋ฏธ์ง€๋ฅผ ์‹ค์‹œ๊ฐ„์œผ๋กœ ์ œ๊ณตํ•  ์ˆ˜ ์—†๋Š” ํ˜„ํ™ฉ์ด๋‹ค. ํ˜„์žฌ์˜ micro/mmW ์ด๋ฏธ์ง• ์‹œ์Šคํ…œ์˜ ๋ฌธ์ œ๋ฅผ ๊ทน๋ณตํ•˜๋ ค๋ฉด ์ƒˆ๋กœ์šด ์‹œ์Šคํ…œ ๊ฐœ๋…์„ ์ œ์•ˆํ•˜๊ณ  ํ…Œ์ŠคํŠธ๋ฒ ๋“œ๋ฅผ ์‹œ์—ฐํ•˜์—ฌ ์ž ์žฌ์ ์ธ ์ด์ ๊ณผ ์œ„ํ—˜์„ ์ž…์ฆํ•˜๋Š” ๊ฒƒ์ด ์ค‘์š”ํ•˜๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” Ku-band์™€ 1D-MIMO ์–ด๋ ˆ์ด๋ฅผ ์ด์šฉํ•œ ๊ด‘๋Œ€์—ญ micro/mmW ์ด๋ฏธ์ง• ์‹œ์Šคํ…œ์ธ Ku1DMIC๋ฅผ ์ œ์•ˆํ•˜์—ฌ ์œ„์™€ ๊ฐ™์€ ๋ฌธ์ œ์ ์„ ๊ทน๋ณตํ•  ์ˆ˜ ์žˆ๋‹ค. ๋น„์šฉ ํšจ์œจ์ ์ธ 3์ฐจ์› ์˜์ƒํ™” ๊ธฐ๋Šฅ์„ ์œ„ํ•ด Ku1DMIC๋Š” 1D-MIMO ๋ฐฐ์—ด ๊ธฐ์ˆ ๊ณผ ISAR(Inverse Synthetic Aperture Radar) ๊ธฐ์ˆ ์„ ์‚ฌ์šฉํ•œ๋‹ค. ๋™์‹œ์— Ku1DMIC๋Š” ์ฃผํŒŒ์ˆ˜ ๋ณ€์กฐ ์—ฐ์†ํŒŒ (FMCW) ๋ ˆ์ด๋”์™€์˜ ์›ํ™œํ•œ ์ธํ„ฐํŽ˜์ด์Šค์˜ ์‹œ์Šคํ…œ ์ˆ˜์ค€ ์„ค๊ณ„๋ฅผ ํ†ตํ•ด ์‹ค์‹œ๊ฐ„ ๋ฐ์ดํ„ฐ ์ˆ˜์ง‘์„ ์ง€์›ํ•œ๋‹ค. Ku1DMIC๋ฅผ ์‚ฌ์šฉํ•œ 3์ฐจ์› ์˜์ƒํ™”์˜ ๊ตฌํ˜„ ๋ฐ ์‹ค์‹œ๊ฐ„ ๊ธฐ๋Šฅ์˜ ๊ฐ€๋Šฅ์„ฑ์„ ๋ณด์—ฌ์ฃผ๊ธฐ ์œ„ํ•ด, 2์ฐจ์› ์˜์ƒํ™”๋ฅผ ์œ„ํ•œ 1D-MIMO RSA๊ณผ 3์ฐจ์› ์˜์ƒํ™”๋ฅผ ์œ„ํ•œ 1D-MIMO-ISAR RSA๊ฐ€ ์ œ์•ˆ๋˜๊ณ  Ku1DMIC์—์„œ ๊ตฌํ˜„๋œ๋‹ค. ๋”ฐ๋ผ์„œ, ๋ณธ ํ•™์œ„ ๋…ผ๋ฌธ์˜ ์ฃผ์š” ๊ธฐ์—ฌ๋Š” Ku-band 1D-MIMO ๋ฐฐ์—ด ๊ธฐ๋ฐ˜ ์˜์ƒํ™” ์‹œ์Šคํ…œ ํ”„๋กœํ† ํƒ€์ž…์„ ๊ฐœ๋ฐœ ๋ฐ ํ…Œ์ŠคํŠธํ•˜๊ณ , ISAR ๊ธฐ๋ฐ˜ 3์ฐจ์› ์˜์ƒํ™” ๊ธฐ๋Šฅ์„ ๊ฒ€์‚ฌํ•˜๊ณ , ์‹ค์‹œ๊ฐ„ 3์ฐจ์› ์˜์ƒํ™” ๊ฐ€๋Šฅ์„ฑ์„ ์กฐ์‚ฌํ•˜๋Š” ๊ฒƒ์ด๋‹ค. ์ด์— ๋Œ€ํ•œ ์„ธ๋ถ€์ ์ธ ๊ธฐ์—ฌ ํ•ญ๋ชฉ์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค. ์ฒซ์งธ, ์‹ค์‹œ๊ฐ„ 2D ๊ทผ๊ฑฐ๋ฆฌ์žฅ ์ด๋ฏธ์ง• ๊ธฐ๋Šฅ์„ ๊ฐ–์ถ˜ Ku ๋Œ€์—ญ MIMO ์ฃผํŒŒ์ˆ˜ ๋ณ€์กฐ ์—ฐ์†ํŒŒ(FMCW) ๋ ˆ์ด๋” ์‹คํ—˜ ํ”Œ๋žซํผ์ธ Ku1DMIC๋ฅผ ์ œ์‹œํ•œ๋‹ค. ์ œ์•ˆํ•˜๋Š” ์‹œ์Šคํ…œ์€ ์ œํ•œ๋œ ์ˆ˜์˜ ์•ˆํ…Œ๋‚˜์—์„œ ๋” ๋„“์€ ์กฐ๋ช… ์˜์—ญ์„ ์ปค๋ฒ„ํ•˜๊ธฐ ์œ„ํ•ด Ku ๋Œ€์—ญ์„ ์‚ฌ์šฉํ•˜๊ณ  ๊ณ ํ•ด์ƒ๋„ ์ด๋ฏธ์ง€๋ฅผ ์ œ๊ณตํ•˜๋ฉด์„œ ๋น ๋ฅธ ๋ ˆ์ด๋” ๋ฐ์ดํ„ฐ ์ˆ˜์ง‘์„ ์œ„ํ•ด ๊ณ ์† ๋žจํ”„ ๋ฐ ๊ด‘๋Œ€์—ญ FMCW ํŒŒํ˜•์„ ์‚ฌ์šฉํ•œ๋‹ค. ํ”Œ๋žซํผ์˜ ํ•ต์‹ฌ ์„ค๊ณ„ ์›์น™์€ ์•ˆ์ •์„ฑ, ์žฌ๊ตฌ์„ฑ ๊ฐ€๋Šฅ์„ฑ ๋ฐ ์‹ค์‹œ๊ฐ„ ๊ธฐ๋Šฅ์œผ๋กœ ์‹œ์Šคํ…œ์˜ ๊ฐ•์ ๊ณผ ์•ฝ์ ์„ ๊ด‘๋ฒ”์œ„ํ•˜๊ฒŒ ํƒ์ƒ‰ํ•œ๋‹ค. ์„ค๊ณ„ ์›์น™์„ ๋งŒ์กฑ์‹œํ‚ค๊ธฐ ์œ„ํ•ด AMD-Xilinx UltraScale+ RFSoC(Radio Frequency System on Chip)๋ฅผ ๊ธฐ๋ฐ˜์œผ๋กœ ๋””์ง€ํ„ธ ์ง€์› ํ”Œ๋žซํผ์„ ์ œ์•ˆํ•˜๊ณ  ๊ตฌํ˜„ํ•œ๋‹ค. ์‹ค์‹œ๊ฐ„ 2D ์ด๋ฏธ์ง•์— ๋Œ€ํ•œ ์‹คํ—˜์  ์กฐ์‚ฌ๋Š” ์ดˆ๋‹น ์•ฝ 60ํ”„๋ ˆ์ž„์—์„œ ๋น„๋””์˜ค ์†๋„ ์ด๋ฏธ์ง•์˜ ๋Šฅ๋ ฅ์„ ์ž…์ฆํ–ˆ๋‹ค. ๋‘˜์งธ, ์˜์ƒ ํ’ˆ์งˆ ํ–ฅ์ƒ์„ ์œ„ํ•œ ํŒŒํ˜• ๋””์ง€ํ„ธ ์ „์น˜์™œ๊ณก(DPD) ๋ฐฉ๋ฒ•๊ณผ ๋ณด์ • ๋ฐฉ๋ฒ•์„ ์ œ์•ˆํ•œ๋‹ค. ์ตœ์ ํ™”๋œ ํŒŒํ˜• ๋ฐœ์ƒ๊ธฐ์˜ ๋„์›€์œผ๋กœ ๊นจ๋—ํ•œ FMCW ํŒŒํ˜•์ด ์ƒ์„ฑ๋˜๋”๋ผ๋„ ํŠนํžˆ ํ”Œ๋žซํผ์˜ RF ํ•˜์œ„ ์‹œ์Šคํ…œ์—์„œ ์‹ ํ˜ธ๋Š” ํ•„์—ฐ์ ์œผ๋กœ ์™œ๊ณก์„ ๊ฒช๊ฒŒ๋œ๋‹ค. ๊ทผ๊ฑฐ๋ฆฌ ์˜์ƒํ™” ์‘์šฉ ๋ถ„์•ผ์—์„œ๋Š” ํŒŒํ˜• DPD๋Š” ๊ด‘๋Œ€์—ญ FMCW ๋ ˆ์ด๋” ์‹œ์Šคํ…œ์˜ ์™œ๊ณก์„ ์–ต์ œํ•˜๋Š” ๋ฐ ํšจ๊ณผ์ ์ด์ง€ ์•Š๋‹ค. ์ด ๋ฌธ์ œ๋ฅผ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•ด Ku1DMIC์—์„œ ํŒŒํ˜• DPD๊ฐ€ ์œ ํšจํ•˜๋„๋ก LO-DPD ์•„ํ‚คํ…์ฒ˜์™€ ์ด์ง„ ํƒ์ƒ‰ ๊ธฐ๋ฐ˜ DPD ์•Œ๊ณ ๋ฆฌ์ฆ˜์„ ์ œ์•ˆํ•œ๋‹ค. ๋˜ํ•œ, ํŒŒํ˜• DPD๋กœ ์ œ๊ฑฐํ•  ์ˆ˜ ์—†๋Š” ๋‚˜๋จธ์ง€ ์˜ค๋ฅ˜๋ฅผ ๋ณด์ƒํ•˜๊ธฐ ์œ„ํ•ด ์ด๋ฏธ์ง€ ์˜์—ญ ์ตœ์ ํ™” ๋ณด์ • ๋ฐฉ๋ฒ•์„ ์ œ์•ˆํ•œ๋‹ค. ๋…ธ์ด์ฆˆ ๋ฐ ํด๋Ÿฌํ„ฐ ์‹ ํ˜ธ์™€ ๊ฐ™์€ ๋‹ค์–‘ํ•œ ์›์น˜ ์•Š๋Š” ์‹ ํ˜ธ์— ๋Œ€ํ•œ ๊ฒฌ๊ณ ์„ฑ์„ ์œ„ํ•ด ์ผ๋ฐ˜ํ™”๋œ Tikhonov ์ •๊ทœํ™” ๋ฐ ์ „์ฒด ๋ณ€๋™(TV) ์ •๊ทœํ™”๋ผ๋Š” ๋‘ ๊ฐ€์ง€ ์ •๊ทœํ™”๋œ ์ตœ์†Œ ์ž์Šน ๋ฌธ์ œ๋ฅผ ์ ์šฉ ํ›„ ๋น„๊ตํ•œ๋‹ค. ๋‹ค์–‘ํ•œ 2์ฐจ์› ์˜์ƒํ™” ์‹คํ—˜์„ ํ†ตํ•ด ๋‘ ๋ฐฉ๋ฒ• ๋ชจ๋‘ ๋ถ€์—ฝ ๋ ˆ๋ฒจ์„ ์ค„์—ฌ ํ™”์งˆ์„ ํ–ฅ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ์Œ์„ ํ™•์ธํ•œ๋‹ค. ๋งˆ์ง€๋ง‰์œผ๋กœ, ISAR ๊ธฐ๋ฒ•์„ 2์ฐจ์› ์˜์ƒ ํ”Œ๋žซํผ์— ์ ์šฉํ•˜์—ฌ ์‹ค์‹œ๊ฐ„ 3์ฐจ์› ์˜์ƒ์„ ๊ตฌํ˜„ํ•˜๊ธฐ ์œ„ํ•œ ์—ฐ๊ตฌ๋ฅผ ์ง„ํ–‰ํ•œ๋‹ค. 1D-MIMO-ISAR ๊ตฌ์„ฑ์—์„œ ์‹ค์‹œ๊ฐ„ 3D ์ด๋ฏธ์ง•์˜ ๊ตฌํ˜„์€ ์ด๋Ÿฌํ•œ ๊ตฌ์„ฑ์ด 3D ์ด๋ฏธ์ง• ์‹œ์Šคํ…œ์˜ ๋น„์šฉ์„ ํฌ๊ฒŒ ์ค„์ผ ์ˆ˜ ์žˆ๋‹ค๋Š” ์ ์—์„œ ์˜ํ–ฅ๋ ฅ์ด ์žˆ๋‹ค. ๋”ฐ๋ผ์„œ ์ด ๋…ผ๋ฌธ์—์„œ๋Š” 1D-MIMO-ISAR ๊ตฌ์„ฑ์— ๋Œ€ํ•œ ์ด๋ฏธ์ง• ์žฌ๊ตฌ์„ฑ์„ ๊ฐ€์†ํ™”ํ•˜๊ธฐ ์œ„ํ•ด 1D-MIMO-ISAR ๋ฒ”์œ„ ์Šคํƒœํ‚น ์•Œ๊ณ ๋ฆฌ์ฆ˜(RSA)์„ ์ œ์•ˆํ•œ๋‹ค. ์ œ์•ˆ๋œ 1D-MIMO-ISAR RSA๋Š” ๋„๋ฆฌ ์•Œ๋ ค์ง„ Back-Projection ์•Œ๊ณ ๋ฆฌ์ฆ˜๊ณผ ๊ฑฐ์˜ ๋™์ผํ•œ ์ด๋ฏธ์ง€ ํ’ˆ์งˆ์„ ์œ ์ง€ํ•˜๋ฉด์„œ๋„ ์ˆ˜๋ฐฑ ๋ฐ€๋ฆฌ์ดˆ ์ด๋‚ด์— ์ด๋ฏธ์ง€๋ฅผ ์žฌ๊ตฌ์„ฑํ•จ์œผ๋กœ์จ ์‹ค์‹œ๊ฐ„ ์˜์ƒํ™”์— ๋Œ€ํ•œ ๊ฐ€๋Šฅ์„ฑ์„ ๋ณด์—ฌ์ค€๋‹ค. ๋˜ํ•œ ๋ฌผ์ฒด๊ฐ€ ์‹œ์•ผ์— ๋“ค์–ด์˜ค๊ณ  ๋‚˜๊ฐ€๋Š” ์‹ค์ œ ์ƒํ™ฉ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•œ ROI ์„ค์ •, ๊ทธ๋ฆฌ๊ณ  ๋ฉ”๋ชจ๋ฆฌ ํ• ๋‹น์— ๋Œ€ํ•œ ์ „๋žต์„ ์„ค๋ช…ํ•œ๋‹ค. ๊ด‘๋ฒ”์œ„ํ•œ ์‹œ๋ฎฌ๋ ˆ์ด์…˜๊ณผ ์‹คํ—˜์„ ํ†ตํ•ด 1D-MIMO-IASR ๊ตฌ์„ฑ ๋ฐ 1D-MIMO-ISAR RSA์˜ ๊ฐ€๋Šฅ์„ฑ๊ณผ ์ž ์žฌ์  ์ด์ ์„ ํ™•์ธํ•œ๋‹ค.1 INTRODUCTION 1 1.1 Microwave and millimeter-wave imaging 1 1.2 Imaging with radar system 2 1.3 Challenges and motivation 5 1.4 Outline of the dissertation 8 2 FUNDAMENTAL OF TWO-DIMENSIONAL IMAGING USING A MIMO RADAR 9 2.1 Signal model 9 2.2 Consideration of waveform 12 2.3 Image reconstruction algorithm 16 2.3.1 Back-projection algorithm 16 2.3.2 1D-MIMO range-migration algorithm 20 2.3.3 1D-MIMO range stacking algorithm 27 2.4 Sampling criteria and resolution 31 2.5 Simulation results 36 3 MIMO-FMCW RADAR IMPLEMENTATION WITH 16 TX - 16 RX ONE- DIMENSIONAL ARRAYS 46 3.1 Wide-band FMCW waveform generator architecture 46 3.2 Overall system architecture 48 3.3 Antenna and RF transceiver module 53 3.4 Wide-band FMCW waveform generator 55 3.5 FPGA-based digital hardware design 63 3.6 System integration and software design 71 3.7 Testing and measurement 75 3.7.1 Chirp waveform measurement 75 3.7.2 Range profile measurement 77 3.7.3 2-D imaging test 79 4 METHODS OF IMAGE QUALITY ENHANCEMENT 84 4.1 Signal model 84 4.2 Digital pre-distortion of chirp signal 86 4.2.1 Proposed DPD hardware system 86 4.2.2 Proposed DPD algorithm 88 4.2.3 Measurement results 90 4.3 Robust calibration method for signal distortion 97 4.3.1 Signal model 98 4.3.2 Problem formulation 99 4.3.3 Measurement results 105 5 THREE-DIMENSIONAL IMAGING USING 1-D ARRAY SYSTEM AND ISAR TECHNIQUE 110 5.1 Formulation for 1D-MIMO-ISAR RSA 111 5.2 Algorithm implementation 114 5.3 Simulation results 120 5.4 Experimental results 122 6 CONCLUSIONS AND FUTURE WORK 127 6.1 Conclusions 127 6.2 Future work 129 6.2.1 Effects of antenna polarization in the Ku-band 129 6.2.2 Forward-looking near-field ISAR configuration 130 6.2.3 Estimation of the movement errors in ISAR configuration 131 Abstract (In Korean) 145 Acknowlegement 148๋ฐ•

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    Time domain based image generation for synthetic aperture radar on field programmable gate arrays

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    Aerial images are important in different scenarios including surface cartography, surveillance, disaster control, height map generation, etc. Synthetic Aperture Radar (SAR) is one way to generate these images even through clouds and in the absence of daylight. For a wide and easy usage of this technology, SAR systems should be small, mounted to Unmanned Aerial Vehicles (UAVs) and process images in real-time. Since UAVs are small and lightweight, more robust (but also more complex) time-domain algorithms are required for good image quality in case of heavy turbulence. Typically the SAR data set size does not allow for ground transmission and processing, while the UAV size does not allow for huge systems and high power consumption to process the data. A small and energy-efficient signal processing system is therefore required. To fill the gap between existing systems that are capable of either high-speed processing or low power consumption, the focus of this thesis is the analysis, design, and implementation of such a system. A survey shows that most architectures either have to high power budgets or too few processing capabilities to match real-time requirements for time-domain-based processing. Therefore, a Field Programmable Gate Array (FPGA) based system is designed, as it allows for high performance and low-power consumption. The Global Backprojection (GBP) is implemented, as it is the standard time-domain-based algorithm which allows for highest image quality at arbitrary trajectories at the complexity of O(N3). To satisfy real-time requirements under all circumstances, the accelerated Fast Factorized Backprojection (FFBP) algorithm with a complexity of O(N2logN) is implemented as well, to allow for a trade-off between image quality and processing time. Additionally, algorithm and design are enhanced to correct the failing assumptions for Frequency Modulated Continuous Wave (FMCW) Radio Detection And Ranging (Radar) data at high velocities. Such sensors offer high-resolution data at considerably low transmit power which is especially interesting for UAVs. A full analysis of all algorithms is carried out, to design a highly utilized architecture for maximum throughput. The process covers the analysis of mathematical steps and approximations for hardware speedup, the analysis of code dependencies for instruction parallelism and the analysis of streaming capabilities, including memory access and caching strategies, as well as parallelization considerations and pipeline analysis. Each architecture is described in all details with its surrounding control structure. As proof of concepts, the architectures are mapped on a Virtex 6 FPGA and results on resource utilization, runtime and image quality are presented and discussed. A special framework allows to scale and port the design to other FPGAs easily and to enable for maximum resource utilization and speedup. The result is streaming architectures that are capable of massive parallelization with a minimum in system stalls. It is shown that real-time processing on FPGAs with strict power budgets in time-domain is possible with the GBP (mid-sized images) and the FFBP (any image size with a trade-off in quality), allowing for a UAV scenario

    Architectures and Algorithms for the Signal Processing of Advanced MIMO Radar Systems

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    This thesis focuses on the research, development and implementation of novel concepts, architectures, demonstrator systems and algorithms for the signal processing of advanced Multiple Input Multiple Output (MIMO) radar systems. The key concept is to address compact system, which have high resolutions and are able to perform a fast radar signal processing, three-dimensional (3D), and four-dimensional (4D) beamforming for radar image generation and target estimation. The idea is to obtain a complete sensing of range, Azimuth and elevation (additionally Doppler as the fourth dimension) from the targets in the radar captures. The radar technology investigated, aims at addressing sev- eral civil and military applications, such as surveillance and detection of targets, both air and ground based, and situational awareness, both in cars and in flying platforms, from helicopters, to Unmanned Aerial Vehicles (UAV) and air-taxis. Several major topics have been targeted. The development of complete systems and innovative FPGA, ARM and software based digital architectures for 3D imaging MIMO radars, which operate in both Time Division Multiplexing (TDM) and Frequency Divi- sion Multiplexing (FDM) modes, with Frequency Modulated Continuous Wave (FMCW) and Orthogonal Frequency Division Multiplexing (OFDM) signals, respectively. The de- velopment of real-time radar signal processing, beamforming and Direction-Of-Arrival (DOA) algorithms for target detection, with particular focus on FFT based, hardware implementable techniques. The study and implementation of advanced system concepts, parametrisation and simulation of next generation real-time digital radars (e.g. OFDM based). The design and development of novel constant envelope orthogonal waveforms for real-time 3D OFDM MIMO radar systems. The MIMO architectures presented in this thesis are a collection of system concepts, de- sign and simulations, as well as complete radar demonstrators systems, with indoor and outdoor measurements. Several of the results shown, come in the form of radar images which have been captured in field-test, in different scenarios, which aid in showing the proper functionality of the systems. The research activities for this thesis, have been carried out on the premises of Air- bus, based in Munich (Germany), as part of a Ph.D. candidate joint program between Airbus and the Polytechnic Department of Engineering and Architecture (Dipartimento Politecnico di Ingegneria e Architettura), of the University of Udine, based in Udine (Italy).Questa tesi si concentra sulla ricerca, lo sviluppo e l\u2019implementazione di nuovi concetti, architetture, sistemi dimostrativi e algoritmi per l\u2019elaborazione dei segnali in sistemi radar avanzati, basati su tecnologia Multiple Input Multiple Output (MIMO). Il con- cetto chiave `e quello di ottenere sistemi compatti, dalle elevate risoluzioni e in grado di eseguire un\u2019elaborazione del segnale radar veloce, un beam-forming tri-dimensionale (3D) e quadri-dimensionale (4D) per la generazione di immagini radar e la stima delle informazioni dei bersagli, detti target. L\u2019idea `e di ottenere una stima completa, che includa la distanza, l\u2019Azimuth e l\u2019elevazione (addizionalmente Doppler come quarta di- mensione) dai target nelle acquisizioni radar. La tecnologia radar indagata ha lo scopo di affrontare diverse applicazioni civili e militari, come la sorveglianza e la rilevazione di targets, sia a livello aereo che a terra, e la consapevolezza situazionale, sia nelle auto che nelle piattaforme di volo, dagli elicotteri, ai Unmanned Aerial Vehicels (UAV) e taxi volanti (air-taxis). Le tematiche affrontante sono molte. Lo sviluppo di sistemi completi e di architetture digitali innovative, basate su tecnologia FPGA, ARM e software, per radar 3D MIMO, che operano in modalit`a Multiplexing Time Division Multiplexing (TDM) e Multiplexing Frequency Diversion (FDM), con segnali di tipo FMCW (Frequency Modulated Contin- uous Wave) e Orthogonal Frequency Division Multiplexing (OFDM), rispettivamente. Lo sviluppo di tecniche di elaborazione del segnale radar in tempo reale, algoritmi di beam-forming e di stima della direzione di arrivo, Direction-Of-Arrival (DOA), dei seg- nali radar, per il rilevamento dei target, con particolare attenzione a processi basati su trasformate di Fourier (FFT). Lo studio e l\u2019implementazione di concetti di sistema avan- zati, parametrizzazione e simulazione di radar digitali di prossima generazione, capaci di operare in tempo reale (ad esempio basati su architetture OFDM). Progettazione e sviluppo di nuove forme d\u2019onda ortogonali ad inviluppo costante per sistemi radar 3D di tipo OFDM MIMO, operanti in tempo reale. Le attivit`a di ricerca di questa tesi sono state svolte presso la compagnia Airbus, con sede a Monaco di Baviera (Germania), nell\u2019ambito di un programma di dottorato, svoltosi in maniera congiunta tra Airbus ed il Dipartimento Politecnico di Ingegneria e Architettura dell\u2019Universit`a di Udine, con sede a Udine

    High Performance Computing via High Level Synthesis

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    As more and more powerful integrated circuits are appearing on the market, more and more applications, with very different requirements and workloads, are making use of the available computing power. This thesis is in particular devoted to High Performance Computing applications, where those trends are carried to the extreme. In this domain, the primary aspects to be taken into consideration are (1) performance (by definition) and (2) energy consumption (since operational costs dominate over procurement costs). These requirements can be satisfied more easily by deploying heterogeneous platforms, which include CPUs, GPUs and FPGAs to provide a broad range of performance and energy-per-operation choices. In particular, as we will see, FPGAs clearly dominate both CPUs and GPUs in terms of energy, and can provide comparable performance. An important aspect of this trend is of course design technology, because these applications were traditionally programmed in high-level languages, while FPGAs required low-level RTL design. The OpenCL (Open Computing Language) developed by the Khronos group enables developers to program CPU, GPU and recently FPGAs using functionally portable (but sadly not performance portable) source code which creates new possibilities and challenges both for research and industry. FPGAs have been always used for mid-size designs and ASIC prototyping thanks to their energy efficient and flexible hardware architecture, but their usage requires hardware design knowledge and laborious design cycles. Several approaches are developed and deployed to address this issue and shorten the gap between software and hardware in FPGA design flow, in order to enable FPGAs to capture a larger portion of the hardware acceleration market in data centers. Moreover, FPGAs usage in data centers is growing already, regardless of and in addition to their use as computational accelerators, because they can be used as high performance, low power and secure switches inside data-centers. High-Level Synthesis (HLS) is the methodology that enables designers to map their applications on FPGAs (and ASICs). It synthesizes parallel hardware from a model originally written C-based programming languages .e.g. C/C++, SystemC and OpenCL. Design space exploration of the variety of implementations that can be obtained from this C model is possible through wide range of optimization techniques and directives, e.g. to pipeline loops and partition memories into multiple banks, which guide RTL generation toward application dependent hardware and benefit designers from flexible parallel architecture of FPGAs. Model Based Design (MBD) is a high-level and visual process used to generate implementations that solve mathematical problems through a varied set of IP-blocks. MBD enables developers with different expertise, e.g. control theory, embedded software development, and hardware design to share a common design framework and contribute to a shared design using the same tool. Simulink, developed by MATLAB, is a model based design tool for simulation and development of complex dynamical systems. Moreover, Simulink embedded code generators can produce verified C/C++ and HDL code from the graphical model. This code can be used to program micro-controllers and FPGAs. This PhD thesis work presents a study using automatic code generator of Simulink to target Xilinx FPGAs using both HDL and C/C++ code to demonstrate capabilities and challenges of high-level synthesis process. To do so, firstly, digital signal processing unit of a real-time radar application is developed using Simulink blocks. Secondly, generated C based model was used for high level synthesis process and finally the implementation cost of HLS is compared to traditional HDL synthesis using Xilinx tool chain. Alternative to model based design approach, this work also presents an analysis on FPGA programming via high-level synthesis techniques for computationally intensive algorithms and demonstrates the importance of HLS by comparing performance-per-watt of GPUs(NVIDIA) and FPGAs(Xilinx) manufactured in the same node running standard OpenCL benchmarks. We conclude that generation of high quality RTL from OpenCL model requires stronger hardware background with respect to the MBD approach, however, the availability of a fast and broad design space exploration ability and portability of the OpenCL code, e.g. to CPUs and GPUs, motivates FPGA industry leaders to provide users with OpenCL software development environment which promises FPGA programming in CPU/GPU-like fashion. Our experiments, through extensive design space exploration(DSE), suggest that FPGAs have higher performance-per-watt with respect to two high-end GPUs manufactured in the same technology(28 nm). Moreover, FPGAs with more available resources and using a more modern process (20 nm) can outperform the tested GPUs while consuming much less power at the cost of more expensive devices

    AUTONOMOUS SURFACE DETECTION AND TRACKING FOR FMCW SNOW RADAR USING FIELD PROGRAMMABLE GATE ARRAYS

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    Sea Ice in Polar Regions is typically covered with a layer of snow. The thermal insulation properties and high albedo of the snow cover insulates the sea ice beneath it, maintaining low temperatures and limiting ice melt, and thus affecting sea ice thickness and growth rates. Remote sensing of snow cover thickness plays a major role in understanding the mass balance of sea ice, inter-annual variability of snow depth, and other factors which directly impact climate change. Researchers at the Center for Remote Sensing of Ice Sheets (CReSIS) at University of Kansas have developed an ultra-wide band FMCW Snow Radar used to measure snow thickness and map internal layers of polar firn from low and high-altitude. This system has shown outstanding performance, but it has some limitations in terms of operational altitude and relies on the operator to make adjustments during surveys to capture radar echoes if the altitude changes significantly. In this thesis, an automated onboard real-time surface tracker for the snow radar is presented to detect snow surface elevation from the aircraft and track changes in the surface elevation. A common technique for an FMCW radar to have a long-range (high-altitude) capability relies on the systemโ€™s ability to delay the reference chirp signal used for de-chirping to maintain a relatively constant beat frequency. Currently, the radar uses an analog filter bank to condition the received IF signal over discrete altitude ranges and store the spectral power in each band utilizing different Nyquist zones. During airborne missions in Polar Regions with the radar, the operator has to manually switch the filter banks whenever there is a significant change in aircraft elevation. The work done in this thesis aims at eliminating the manual switching operation and providing the radar with surface detection, chirp delay, and a constant beat frequency feedback loop to enhance its long-range capability and ensure autonomous operation
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