青云翻译

Because it can not be modulated signal light and the background to distinguish, so the measurement error is large.

Background light because it will not be apart from modulated signals, measuring error is very large.

Because it cannot differentiates the background light and the modulation signal, therefore the measuring error is very big.

Since it cannot be separated from background light with modulation signal zone, so measurement error.

Background light because it will not be apart from modulated signals, measuring error is very large.