綜觀軍事通訊發展，在軍事電子戰應用上，針對戰場上的頻譜監控與訊號情報蒐集，如何在高複雜電磁環境下截獲敵方未知通聯訊號，快速的完成偵測、辨識、解譯，以即時獲取敵方情資，在電子戰中至關重要，其中訊號調變類型自動分類，為軍事通訊截收中的關鍵技術。 傳統基於特徵擷取(feature extraction)的訊號調變分類的方法，需要事先分析出各種特徵參數，再利用決策樹(decision tree)或各種機器學習(machine learning)的方式，從擷取到的特徵資料中訓練出有效的分類模型，此種方式仰賴人為擷取的特徵能夠確實提供訊號分類所需的完整資訊，然而面對通道的各種變化，人工分析得到的特徵值(expert feature)往往會受到干擾而造成分類效果不佳。 本文提出基於卷積網路(Convolutional Neural Network)之調變分類技術，神經網路可從訓練資料(training data)中自我學習(learning from data)，自動擷取特徵並分類，實驗結果顯示，深度卷積神經網路的分類方式有更好的抗干擾性，我們綜合了各個測試的成果，提出的模型在SNR為0dB~20dB 的範圍內，調變分類預測的準確度達到94.05%的不錯表現。;While investigating the development of military communication in the application of military electronic warfare, how to detect, identify and decode signals of interesting in the high-complex electromagnetic environment is extremely important. Automatic modulation recognition and classification has become a necessary technology in military electronic warfare.
Based on feature extraction, traditional modulation classification require prior analysis of various feature parameters, and then use decision trees or machine learning methods to extract features. The classification model is trained based on the captured features. This method relies on the expert features providing sufficient information for signal classification. However, in the face of varied communication channel, the artificial expert features often be interfered and causes poor classification results.
This paper proposes a modulation classification technique based on Convolutional Neural Network. The neural network can learn from training data, extract features and classify signals automatically. The experimental results show that modulation classification using convolutional neural network provide better anti-interference performance. Analyses show that the proposed model yields an average classification accuracy of 94.05% at varying SNR conditions ranging from 0dB to 20dB.
