文档为信噪比的定义，包括平均功率信噪比、瞬时功率(或电压)信噪比和偏移信噪比，并给出详细的定义公式-The definition of the documentation for the signal-to-noise ratio, signal-to-noise ratio of the average power signal-to-noise ratio and offset signal-to-noise ratio of the instantaneous power (or volt