Algorithm Of FM Demodulation Based On The Software Radio

Software radio is one of the important research directions of current mobile communications. It uses a hardware launch platform to let each software part realize its functions, as well as all of the various communication modes demodulated without changing any hardware, and then let the communications architecture unitized ultimately. This paper dose a deep research on the theory of receiving platform based on software radio, and has various modulation communication theories recognized, by focusing on demodulation algorithm simulation.First, this paper introduces several key technologies including intelligent antenna, analog-to-digital conversion and fast digital signal processing as the important part of the structure of software radio. Then, several kinds of modulation signals are analyzed, their general expressions are gotten by using the characteristics of the digital modulation and demodulation signals, and further, the orthogonal expression forms are gotten for several general modulation signals.Second, this paper analyses the instantaneous amplitude, frequency and phase characteristics, and the modulation pattern recognition algorithm based on the theory of decision. Through the modeling simulation for various kinds of signals, several signal modulation pattern distinguish thresholds is gotten. Using these thresholds, the receiving terminals can recognize the modulation pattern of the received signals, and the recognition performances are simulated.Finally, the paper makes simulation focusing on the software radio receiving platform, by dealing with the generated modulation signals, analyzing the signal demodulation quality. The influences caused by carrier synchronization and timing synchronization are deeply considered, as well as the influences on BER caused by the code rates of FM signals, and at last, the reliability of the receivers are estimated.