Study And Design On Digital Modem

Software Radio, with the digital signal processing technology as the core, is based on modern communication theory, and supported by microelectronics technology. As the software radio can get rid of the shackles of the hardware architecture, it has very important value of commercial and military applications, which is known as a wireless communications technology revolution.In software radio, modem occupies a central position. With the development of the technology, design the modem for communication system in digital mode is an important technology of modern communications. Based on the study of software radio technology and digital processing method for analog signal, the analysis of modem parameters, and the principle, structure and implementation of digital MSK modem, were studied in this thesis.In this thesis, a FPGA-based digital MSK mode is studied, and implemented. The mode design results were verified with DE2-70 hardware system. The main content includes two parts:1. Research on the MSK modulation and demodulation. Traditional binary digital modulation methods are 2FSK,2PSK and 2ASK. In this paper, through the analysis of the three types of modulation, FSK modulation mode is selected according to the needs of the practical application. However, through analysis of shortcomings of the 2FSK, the definition of MSK is introduced and its FPGA-implementation is studied.2. MSK digital modem implementation. In this paper, a complete application example design is provided, which uses the full MSK digital modulation and demodulation method based on FPGA. The FPGA chip of the system used is EP2C70, and the software is QuartusⅡ6.0. With embedded logic analyzer- Signal TapⅡ, the various signals in the system can be observed on real-time. The final design results show that the design requirements are satisfied through the software simulation and hardware functional verification.