Development of detection methods for signals with different dimming levels

In the first part of the thesis, a new transmission scheme is proposed by using signal characteristics of the variable pulse position modulation (VPPM) technique. In the proposed system, 4 information bits are transmitted every three bits. Therefore, the proposed system has been observed to have better spectral efficiency than traditional systems with dimming level lower than 35% and higher than 65%. In the second part of the thesis, it is aimed to detect the information bits without having the dimming level information. In the part, two different detection methods have been developed, and the first method is to generate a hybrid signal using artificial neural networks (ANN). When the proposed system is compared to the traditional system that doesn't know the dimming level information, it has been observed that the proposed system has better bit error rate performance, but it also gives lower bit error rate performance than the system with excellent dimming level information. In order to solve this problem, a second method has been developed to estimate the dimming levels of the signals. When the dimming levels of the signals are changed at the transmitting side, it is impossible for the traditional system to have dimming level information at the receiving side without transmitting information signal. However, assuming that the traditional system knows all the signal characteristics, the BER performance of the proposed and traditional systems are almost the same under 10-3. As a result, thanks to the proposed system, a receiver scheme has been developed that it can estimate the information bits of VPPM signals without the need for the dimming level information.