针对现有多进制正交幅度调制(MQAM)信号调制方式的不足，提出了一种改进的MQAM信号调制识别算法。该算法对通信系统中信号的信噪比(SNR)进行估计，通过计算 MQAM信号矢量图的最小环带的方差，得到不同调制类型的 QAM最小环带的方差，最后根据估计的 SNR与信号求出合适的参考门限，与之前求出的最小环带的方差进行比较，完成调制方式的识别。该算法运算量小，识别率高，且适用于实际工程应用。仿真结果表明在 SNR≥-1 dB时，5种不同阶数的 QAM信号的识别概率≥96%。%Aiming at the problem of existing modulation recognition algorithm for Multiple Quadrature Amplitude Modulation(MQAM) signals, an improved MQAM signal modulation recognition algorithm is developed. The Signal to Noise Ratio(SNR) in the communication system is estimated primarily, and then different types of QAM modulation minimum ring variance are obtained by calculating the minimum ring variance of MQAM signal vector diagram. The modulation mode recognition is completed by comparing an appropriate reference threshold calculated by the estimated SNR and signal with above calculated variance. The algorithm is of small computational complexity and high recognition probability. Moreover, the algorithm can be applied to modulation recognition of practical engineering. The simulation results illustrate that the recognition probabilities of QAM signals with 5 different orders are equal or greater than 96%under SNR≥-1 dB.
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