Cliff effect

In telecommunications, the (digital) cliff effect or brick-wall effect is a sudden loss of digital signal reception. Unlike analog signals, which gradually fade when signal strength decreases or electromagnetic interference or multipath increases, a digital signal provides data which is either perfect or non-existent at the receiving end. It is named for a graph of reception quality versus signal quality, where the digital signal "falls off a cliff" instead of having a gradual rolloff.^[1] This is an example of an EXIT chart.

The phenomenon is primarily seen in broadcasting, where signal strength is liable to vary, rather than in recorded media, which generally have a good signal. However, it may be seen in significantly damaged media that is at the edge of readability.