数字水印进行LPM 和DFT变换，LMP变换后图像将抵抗旋转等攻击,Digital Watermarking for LPM and the DFT transform, LMP will be transformed image rotation, such as resistance to attack

用matlab绘制线性调频信号的时域波形，同时对信号进行频谱分析，并考察采样频率以及信噪比对频谱分析的影响。-Matlab drawing with linear frequency modulation signal time-domain waveform, and spectral analysis of signals and the sampling frequency and signal to noise ratio study of the impact of spectrum