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Mathematical Problems in Engineering
Volume 2015, Article ID 516081, 7 pages
Research Article

An Accurate Modulation Recognition Method of QPSK Signal

School of Information Science and Engineering, Shenyang Ligong University, Shenyang 110159, China

Received 5 November 2014; Revised 21 April 2015; Accepted 19 May 2015

Academic Editor: Chih-Cheng Hung

Copyright © 2015 Yongxin Feng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Quadrature phase shift keying (QPSK) modulation has been widely applied in communication systems. With the increasing development of QPSK modulation recognition, it is meaningful for ensuring validity and accuracy of recognition method. Therefore, the method of signal recognition has been presented based on the features of QPSK modulated signal, in which the feature parameters of QPSK signal are extracted. Besides, signal classification is fulfilled through thresholds, and modulation recognition is completed with quartic spectrum. The simulation results show that, the method can recognize QPSK modulation effectively in less sample space condition and can be more accurate.