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اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1392

دوازده،150ص.: مصور،جدول،نمودار ﴿رنگي﴾

ص.ع.به فارسي و انگليسي

محمود مدرس هاشمي

17/4/93

محمد صادق فاضل، مجتبي بهشتي

مهندسي برق و كامپيوتر

ID8441

چكيده 1 فصل اول مقدمه 2 1 1 مفهوم تصوير 3 1 2 ويژگي تصاوير راداري 3 1 3 تاريخچه 4 SAR 1 4 هدف و ساختار پايان نامه 6 فصل دوم اصول كلي رادارهاي روزنه مصنوعي 8 2 1 مقدمه 8 2 2 مودهاي تصوير برداري در 11 SAR 2 2 1 مود نواري 11 2 2 2 مود اسكن 11 2 2 3 مود تابش نقطه اي 11 2 3 سيگنال LFM و خواص آن 11 2 3 1 اصل فاز ايستان 21 2 3 2 طيف سيگنال چيرپ 31 2 4 قدرت تفكيك در 14 SAR 2 5 قدرت تفكيك در راستاي برد 61 2 5 1 فيلتر منطبق 11 2 5 2 پردازش انبساطي 11 2 6 قدرت تفكيك در راستاي سمت 22 2 7 ويژگي هاي سيگنال 24 SAR 2 7 1 جمع آوري و ذخيره سازي داده هاي 22 SAR 2 7 2 پديده مهاجرت سلول برد 62 2 7 3 معادله برد 12 2 7 4 ويژگي هاي سيگنال برد 12 2 7 5 ويژگي هاي سيگنال سمت 13 2 8 پاسخ ضربه 33 SAR هشت

Ehsan Raei Dehaghi e raei@ec iut ac ir Date of Submission Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M sc Language Persian Supervisor Dr Mahmoud Modarres Hashemi modarres@cc iut ac irAbstract Remote sensing is the science related to gathering information without direct contact with aphenomenon Synthetic aperture radar SAR due to their wide applications and highperformances have an important role in this field The function of SAR which is categorizedas airborne and spaceborne radars is the same as pulsed radars In the SAR the transmittedsignal is generally Chirp and the received signal is expansioned in both range and azimuth intwo dimensional directions where it named as raw data SAR There is a relative motionbetween the radar platform and target point and so the distance from the radar platform totarget point during synthetic aperture varies This makes the target data to move towards therange direction and it is called the Range Cell Migration RCM So for extracting image theimage forming algorithms must be performed There are various algorithms for imageformation and one of the most commonly used is the Range Doppler Algorithms RDA Oneof the important parameter in SAR is image resolution in both directions of range and azimuthand using the chirp signal improves these resolutions There are some methods forcompressing of the chirp signal in the receiver wherein the SAR generally matched filter isutilized But recently the Fractional Fourier Transform FrFT is proposed in chirp signalcompression and ISLR criterion shows that it has better performance than the matched filter Since FrFT has the ability to eliminate the second order factors on the signal phase and RCMhas the second order polynomial equation in this thesis an algorithm is presented based onRDA wherein the RCM is corrected too by the use of FrFT in addition to pulse compression Coherent processing of the raw data which is considered as one of the most important issue inimage formation algorithms requires the maintenance phase sequence of the received signalat the receiver Since the range equation affects in the received signal phase the radarplatform must moves in a predetermined direction to have coherent processing But due to thelack of ideal navigation systems and the presence of atmospheric disturbances deviation frompredetermined path is inevitable This phenomenon is termed as the error motion In practice the amount of displacement of the actual trajectory should be measured from the idealtrajectory and the additional amount of signal phase for coherent processing is added thisprocedure is called motion compensation Range equation not only effects on the receivedsignal phase but also it affects the delay of the received signal called the Non symmetricrange cell migration NsRCM Conventional methods for motion compensation techniqueonly compensate the error on the phase of the azimuth signal In this thesis a new method isproposed for motion compensation where the NsRCM is considered and its effect iscompensated Simulation results show that the proposed compensation algorithms has betterperformance based on IRW PSLR and ISLR criteria Keywords Synthetic Aperture Radar Chirp Signal Range Cell Migration Image Formation Fractional Fourier Transform Motion Compensation

محمود مدرس هاشمي

محمد صادق فاضل، مجتبي بهشتي