NEW EDGE DETECTORS FOR CODED MARK INVERSION TRANSMISSION WITH ENHANCED PERFORMANCE
This thesis is concerned with the analysis and measurement of the bit error rate performance of edge detectors for Coded Mark Inversion (CMI) data transmission. Chapter 1 gives the introduction to the CMI data transmission system, the motivation and the goal of the study are presented. Chapter 2 presents a general description on CMI line code and compares the power spectra of CMI line code with Manchester code. In chapter 3, an edge decoder for the CMl transmission which examines the threshold crossing of the received signal is proposed. The principle of the decoder is analogous to a level crossing problem. The performance of such a decoder is also analysed. In chapter 4, new edge detecting schemes to enhance the performance of the simple edge decoder presented in chapter 3 are proposed. One of these edge detectors is shown to be able to reject false alarm errors while the other is able to partially reject wrong slot errors. These new decoders are constructed and error rate performance are measured over an additive white Gaussian noise channel. These performance are compared with the simple decoder in order to show the improvement gained. New error probability fom1Ulae which are shown to predict the measured error rates well are derived. The measured bit error rates of the new edge detecting schemes is presented in chapter 5. The noise characteristics of several optical receivers is measured in chapter 6. The data are used in computing the bit error rate performance in Chapter 7. The measured bit error rates are then compared with the computed performance. Chapter 8 presents our conclusion.
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