.8 Psk + Tcm Coded Modulation Demodulation Techniques

For the past few years, with the requirement of the population, the technology of the communication has advanced with exceptional speed. First, the communication system should have the high capacity. Secondly, the operating factor of the frequency and the quality of the communication should not be ignored. With the development of the communication, we are short of the bandwidth resources. How to accomplish the communication of high quality is the goal we are always pursuing. So as one of the methods to solve the questions, TCM technology is proposed.In this dissertation, the Trellis Coded Modulation and Demodulation technology is described. This technology is based on the method of partition in subclass brought by Ungerboeck. It can achieve a power gain of 3-6dB in the case that the transmission bandwidth and speed are not be changed. The method of demodulation of TCM+8PSK is Viterbi decoding. When the signal get through from the white Gaussian noise channel, it will be decoded with less errors by the method of Viterbi decoding. In the latest years, this technology has been developed quickly and it can be applicable in a lot of kinds of domains instead of other technologies. For example, it can be applicable in satellite communication, speech recognition systems and multiuser detection.This paper describes the implement method of TCM based on FPGA. It can solve the question of the limited frequency bandwidth when data is transported at a high speed. The encoding is combined to 8PSK technology to avoid the weakness of one separate technology. The aim is to make sure the communication quality in the complex channel. Besides, the paper proposes the Viterbi decoding based on Euclidean distance, which is an improved method. It is worth noting that the traditional one is focused on comparing the hamming distance while the method in this paper compares the Euclid distance, and the state in the grid pattern indicates the waveform. This paper describes the principal of the Trellis Coded Modulation at first. Then matlab and FPGA is used to complete the generation and the demodulation of the TCM signal.