采用数据拟合法进行的高斯白噪声信道下的信噪比估计，程序中有经典summer法以及本人自己拟合的二阶和三阶参数，适用于不同的信噪比范围，望大家一起交流-By data fitting of the Gauss white noise channel SNR estimation, the program in the classic summer method as well as my own fitting of the two order and three order parameters