基于瞬时频率的数字调制方式自动识别算法

数字通信信号调制方式的自动识别在军用和民用方面都极为重要。为了自动识别FSK2,FSK4,PSK2,PSK4四种数字信号的调制方式,提出一种新的瞬时频率提取方法,该方法不需要对相位进行去卷叠处理,也不需要实现码元同步,与现有方法相比,运算量显著减少,鲁棒性强,可用于实时处理中。在此基础上提出三个特征参数和一种基于判决理论的调制方式自动识别算法,给出识别算法的实现流程。计算机仿真结果表明,在信噪比为-3 dB时,识别算法的平均识别率大于等于99%,证明新的瞬时频率提取方法和调制方式自动识别算法是有效的,有望用于实际的非协作通信系统中信号的检测和快速识别。

Algorithm for Automatic Modulation Recognition of Digitally Modulated Signals Based on Instantaneous Frequency

Automatic modulation recognition of digital communication signals is extremely important for both military and civilian purposes. In this paper, a new method for extracting the instantaneous frequency of the intercepted signals is proposed to automatically recognize the modulation types of FSK2, FSK4, PSK2 and PSK4 signals. This new method has no need of phase-unwrapping or symbol synchronization. Compared to other available approaches, it has greatly reduced the processing power consumption. Furthermore, this method is much more robust and can be used in real-time application systems. On the basis of this, three key features and an algorithm for modulation recognition of the aforementioned four types of signals are derived. This algorithm is based on the decision-theoretic approach and its realization flowchart is also presented. Computer simulations show that the average modulation recognition success rate is ≥99% at an SNR of -3 dB. It proves that the new method for the instantaneous frequency extracting is efficient and the modulation recognition algorithm is suitable for the practical application of signal detection and fast recognition in non-cooperation communication systems.