用于大气激光通信的数字图像水印研究

Research on Image Watermarking Applied to the Atmospheric Laser Communication

通过分析大气衰减和大气湍流,可认为大气信道模型是高斯噪声信道,提出了结合多小波SPIHT和低密度奇偶校验码(LDPC)的数字图像水印算法作为联合信源信道编码用于大气激光通信.该算法利用了多小波SPIHT算法的信源编码高效性、鲁棒性和LDPC码的低误码性能,根据信源编码后数据在重建时的重要程度,进行不同等纠错保护的信道编码.仿真结果表明,在加性高斯白噪声(AWGN)信道中采用PPM调制方式,信噪比为14dB时,经过大气激光信道恢复出的水印归一化相关系数为0.863,纠正突发错误和随机错误的能力均很强,适用于大气激光通信的恶劣环境和保密通信.

The influence of atmospheric attenuation and turbulence to laser transmission are profoundly analyzed.The Gaussian noise channel model is present.A robust image watermark algorithm is proposed based on multi-wavelets SPIHT and low density parity check codes（LDPC）.The algorithm is applied in the atmospheric laser communication by Joint Source-Channel Coding（JSCC）.The presented algorithm takes advantage of source coding efficiency and robustness of multi-wavelets SPIHT algorithm and low bit error performance of LDPC code.According to the importance of the encoded data in the redevelopment,a different level error correction channel coding is built.In the additive white Gaussian noise（AWGN） channel with PPM modulation,and the SNR of 14dB through the atmosphere laser channel,normalized correlation coefficient of the recovered watermark is 0.863.The presented algorithm has strong error correction performance in burst errors and random errors,so it is appropriate for complicated environment of atmospheric laser communication and confidentiality communication,and has good application prospect.