POWER MARGIN

The difference between available signal power and the minimum signal power needed to overcome system losses and still satisfy the minimum input requirements of the receiver for a given performance level. Note: System power margin reflects the excess signal level , present at the input of the receiver, that is available to compensate for (a) the effects of component aging in the transmitter, receiver, or physical transmission medium , and (b) a deterioration in propagation conditions. Synonym system power margin.