A Research of PPM in Digital Communication : The Influence of SNR

Automatic modulation identification and parameter estimation of digital communication signals are the key technologies in communication systems. In recent years, with the rapid development of modern communication and signal processing technology, the communication signal system and modulation style are becoming more complex and diverse. In addition, the signal transmission environment has become increasingly bad, all of these changes make the communication signal identification, and parameters estimation requirements are getting higher and higher. In this paper, we study some modulation and demodulation methods in digital communication. According to the published literature at home and abroad and our simulations, the theory of automatic modulation recognition for communication signals is increasingly rich and perfect, especially in the low SNR of modulation recognition and parameter estimation problem under the condition of more concern.