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Study On Generation Of QAM Signal With Microwave Photonics Technology

Posted on:2015-07-03Degree:MasterType:Thesis
Country:ChinaCandidate:Y H XuFull Text:PDF
GTID:2308330479976271Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
With the development of the next generation wide and ultra-wide band communication technology, the signal sampling rate is continuously increasing and the signal bandwidth is also growing fast. The existing communication system which is based on current electronic signal processing will face a huge challenge, so-called ‘electronic bottleneck’. Compared with the traditional electrical method, the microwave photonic systems feature higher working frequency, larger operation bandwidth, lower loss with long transmission and immunity to electromagnetic interference. With these characteristics, microwave photonics technology become one of most effective solutions to the electrical challenges, and have been drawing a lot of attention in the past decades. Quadrature amplitude modulated(QAM) signal is widely used in communication systems due to its efficiently usage of the spectrum and the easy realization of the modulation or demodulation. So that it is of great importance to study the generation method of QAM signal with photonic technology. The main work of this thesis is as follows:The first chapter briefly introduces the concept of QAM modulation signal, the development history, the photonic methods for QAM signal generation, the significance of the optical wireless communication system, the current situation of the development of expounded and the main contents in this thesis.The second chapter summarizes the devices used in simulation and experiment in testing the microwave photonic QAM signals. First of all, the operation principle of the intensity modulator, the phase modulator, the polarization modulator and the Mach-Zehnder modulator are introduced. Then, the performance of several optical amplifier and Raman amplifier, e.g., the semiconductor optical amplifier, erbium doped fiber amplifier are analyzed. Finally, the laser, optical fiber and other commonly used components are introduced.The third chapter introduces two schemes of the proposed QAM signal generation system, which is based on the parallel intensity modulations or the parallel polarization modulations. The first proposed scheme are tested by generating 4QAM and 16 QAM signals, while the other proposed scheme are tested by generating 4QAM signals, all by using the software of OptiSystem. Both theoretical analysis and simulation experiment results are given to demonstrate their validities.The fourth chapter shows the structures of the experimental system and the test results. The principle of the polarization modulation based microwave photonic phase shifter is firstly analyzed. Then, using the existing equipments of our laboratory, the generation of 4QAM signal based on the parallel intensity modulations method is successfully realized. The waveforms, eye diagrams and the demodulated constellation diagrams are shown to verify the effectiveness and its potential benefits in real applications.The fifth chapter is the conclusion. The whole work is summarized, and the further research direction is pointed out.
Keywords/Search Tags:Microwave photonics, Microwave photonic phase shifter, Quadrature amplitude modulation(QAM), Intensity modulation, Polarization modulation
PDF Full Text Request
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