Noise Margin

The technical term Noise Margin ( German reserve about a signal level to the noise level ) refers to those communications engineering level to which a useful signal to be a recipient of information greater than a disturbance, in order to achieve error- free reception of the desired signal. The disturbance is described as physical noise size ( engl. Noise).

In other words, the Noise Margin is a lower limit of the signal -to-noise ratio, which requires the receiver for error-free reception of the transmitted information. Is the signal -to-noise ratio is less than the noise margin, it is within the scope of the data transmission to transmission errors. The Noise Margin can be effected by the action of a large disturbance, such as noise, are too small, or the attenuation of the useful signal in the transmission channel.

The Noise Margin, as the signal -to-noise ratio, measured as a dimensionless quantity in the unit Bel. In the telecommunications sector, for example in digital subscriber lines (DSL), this value should not be less than 3 dB to 4 dB.