Σε αυτήν την διπλωματική εργασία ασχοληθήκαμε με την υλοποίηση των κριτηρίων έγκυρου τερματισμού του Turbo αποκωδικοποιητή σε συσκευή FPGA. Στο πρώτο κεφάλαιο παρουσιάζουμε το θεωρητικό υπόβαθρο που περιλαμβάνει βασικές έννοιες των ψηφιακών επικοινωνιών και την μαθηματική υποστήριξη του turbo κώδικα. Στο δεύτερο κεφάλαιο παρουσιάζονται τα αποτελέσματα της εξομοίωσης του κώδικα. Στο τρίτο κεφάλαιο παρουσιάζεται αρχιτεκτονική του κυκλώματος που υλοποιεί τον turbo κώδικα τόσο από την πλευρά του κωδικοποιητή όσο και από την πλευρά του αποκωδικοποιητή. Εν συνεχεία, στο κεφάλαιο 4 παρουσιάζεται το προτεινόμενο κριτήριο τερματισμού μαζί με την δική του υλοποίηση καθώς και την υλοποίηση τριών άλλων κριτηρίων. Στο τέλος παρουσιάζουμε τα συμπερασματά μας και τις μετρήσεις μας. / In this thesis we studied the implementation of the termination criteria of the turbo decoder as well as its implementation on the hardware. In the first chapter an introduction to fundamental concepts of digital communication as well as their mathimatical expression. In the second chapter the results of the simulation of the code are presented. In the third chapter the architecture of the turbo encoder and decoder are presented. In the fourth chapter a new termination criterion is presented with the implementation of tree other criteria. Finally we present our conclusions and our measurements.

Until the developments in computer technology, linear test administrations within classical test theory framework is mostly used in testing practices. These tests contain a set of predefined items in a large range of difficulty values for collecting information from students at various ability levels. However, placing very easy and very difficult items in the same test not only cause wasting time and effort but also introduces possible extraneous variables into the measurement process such as possibility of guessing, chance of careless errors induced by boredom or frustration. Instead of administering a linear test there is another option that adapts the difficulty of test according to the ability level of examinees which is named as computerized adaptive test. Computerized adaptive tests use item response theory as a measurement framework and have algorithms responsible for item selection, ability estimation, starting rule and test termination. The present study aims to determine the applicability of computerized adaptive testing (CAT) to Turkish Pupil Monitoring System&rsquo / s (PMS) mathematics assessments. Therefore, live CAT study using only multiple choice items is designed to investigate whether to obtain comparable ability estimations. Afterwards, a Monte Carlo simulation study and a Post-hoc simulation study are designed to determine the optimum CAT algorithm for Turkish PMS mathematics assessments. In the simulation studies, both multiple-choice and open-ended items are used and different scenarios are tested regarding various starting rules, termination criterion, ability estimation methods and existence of exposure/content controls. The results of the study indicate that using Weighted Maximum Likelihood (WML) ability estimation method, easy initial item difficulty as starting rule and a fixed test reliability termination criterion (0.30 standard error as termination rule) gives the optimum CAT algorithm for Turkish PMS mathematics assessment. Additionally, item exposure and content control strategies have a positive impact on providing comparable ability estimations.