关键词: 离散余弦变换（DCT）, 酉矩阵, 时频域, 数字水印

Abstract: In view of underwater acoustic emission source is more. To identify the enemy emission source sonar accurately, combined with the time-frequency domain characteristics of DCT（Discrete Cosine Transform）, time-frequency coefficients embedded watermark identification method is proposed based on DCT. Through the time-frequency coefficients of discrete cosine transform to embed digital watermark, this method considers the channel characteristics to generate watermark, combined with the basic characteristics of two-dimensional DCT matrix to change the embedding position of the watermark and the watermark number for simulation test. The detection performance simulation results show that the proposed method can achieve the best way to achieve the optimal embedding without affecting the signal itself, the performance of the detection accuracy can be improved.

Key words: Discrete Cosine Transform（DCT）, unitary matrix, time-frequency domain, digital watermark