3000

2853

كارشناسي ارشد

﴿برق - مخابرات﴾

اصفهان:دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1383

[نه]، 108، [II]ٌٌص.: مصور، جدول، شكل، نمودار

محمود مدرس هاشمي

سعيد صدري

عليمحمد دوست حسيني، محمد رضا آشوري

1396/02/30

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID2853

به فارسي و انگليسي : قابل رويت در نسخه ديجيتالي

AbstractNowadays radar systems play an essential role in military and civil applications One of themost important applications of radar is imaging for target identification Inverse syntheticaperture radar ISAR uses target s motion to generate images on the range doppler plane Conventional radar imaging uses the Fourier transform to retrieve Doppler information However due to the complex motions ofa target the Doppler frequency shifts are actuallytime varying Using the Fourier transform the Doppler spectrum becomes meared and theimage is blurred The joint time frequency transforms can effectively resolve the imageblurring Additionally they increase the SNR and can be used for several targets In thisthesis using the entropy and contrast criterions on the complete ISAR image and also onindividual range cells the perfor mance of these criterions for adjusting the window lengthin STFT is investigated and the result is compared with Fourier transform Simulationsshow that the local entropy method has excellent performance for all rotation angles of thetarget and even at small SNR s Especially when target rotates fast this method performsbetter than the Fourier transform This method can optimally adjust the window length of ajoint time frequency transform typically STFT for larger concentrations of the scatterersand more focus of the image l J r V u r Jfll If V JJ Iq

محمود مدرس هاشمي

سعيد صدري

عليمحمد دوست حسيني، محمد رضا آشوري