my_noise文件是已知信号方差，加入信号噪声，可以加入高斯噪声，淑盐噪声,等其他噪声十分有用

其他两个函数时加入噪声信噪比SNR,但是有一点,这种方法并不准确,不能保证加入噪声信噪比为SNR,实际测试中可以看出,但是可以加入相同的信噪比的噪声-my_noise document is known to signal variance, by adding signal noise, Gaussian noise can be added, suk salt noise, noise, and other very useful function when the other two noise signal to noise ratio SNR, but there is one point, this method is not accurate , can not be guaranteed by adding the noise signal to noise ratio for the SNR, the actual test can be seen, but can join the same noise signal to noise ratio