Study Of Modulation/modulation Of 16-QAM Based On Software-Defined Radio

As a high efficiency digital modulation and demodulation scheme, 16-QAM is widely used in HDTV, satellite communication, microwave communication and so on. In the communication system, the method of modulation and demodulation based on soft-defined radio (SDR) is the aim of the development of technology. SDR is a kind of new technology in communication area. Its key idea is establishing an open, standardized and modular hardware platform to complete all kinds of functions like modulation and demodulation with software. Its main characters are software flexibility and open structure.This paper studies detailedly the modulation and demodulation of 16-QAM based on SDR, and establishes, simulates the models using Simulink. This paper includes the main contents as follows.1. The architecture and theory of 16-QAM modulator/demodulator are analyzed. And the theory of the production of 16-QAM signal and some key steps in demodulation are introduced.2. The model of 16-QAM modulator is established and simulated using Simulink according to the basic theory.3. The model of 16-QAM demodulator is established using Simulink according to the basic theory. The arithmetic of symbol timing recovery and carrier recovery are analyzed and discussed. In the part of symbol timing recovery, interpolation filter, timing-error detector, loop filter and numerically controlled oscillators are analyzed detailedly. And traditional timing algorithm is improved in timing-error detector. In the part of carrier recovery, the theory is presented and decision-directed algorithm is used.4. A whole 16-QAM model is established and simulated using Simulink. Generally speaking, the technology of 16-QAM based on SDR is analyzed and studied, and a whole system communication model is established and simulated using Simulink to prove the design is right.