9221

8523

كارشناسي ارشد

مخابرات﴿سيستم﴾

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1393

ده،96ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

علي محمد دوست حسيني

مسعود عمومي

7/8/93

مهندسي برق و كامپيوتر

ID8523

Abstract One of the important issues in laser radar Lidar systems that work based on photon counting photodetectors is the time of arrival delay estimation of received optical pulses It has been a significant research concept from the early days using these detectors Based upon previous works it seems that further studies in two aspects are reasonable First although finding error bounds is necessary it is insufficient to design practical estimators therefore finding practical manners to achieve desirable estimates is necessary Second we must try to adjust estimation conditions to real environments In this thesis we present the maximum likelihood ML delay estimation formulation by assuming received Gaussian optical pulse and considering detector dead time under no background condition We examine three approximation techniques to solve this equation Because our focus lies on long range laser radars we use appropriate delay values according to this system s operation ranges Furthermore we consider intuitive mean and count rate based methods Simulation results verify that these intuitive methods show success in some complex such as in no background noise conditions when our ML approximation methods fail to work successfully We also identify the suitable method for each delay according to the pulse widths Background noise and detector jitter effects are considered next At first we neglect the background noise events outside signal duration and later by considering the symmetric exterior to the background noise events distribution around the actual delay Due to undesirable results that were attained from previous solutions in nonsymmetrical background noise events distribution we apply a new track type ad hoc method to overcome this problem Simulation results show that this method can be successful in this case Finally in a different attitude we propose a new technique for detecting significant delay variations Simulation results show that our proposed algorithm can detect delay variations that are greater than or equal to 1 5 times the primary delay Keywords 1 Lidar 2 dead time 3 background noise 4 photon counting photodetector 5 jitterPDF created with pdfFactory trial version www pdffactory com

علي محمد دوست حسيني

مسعود عمومي