Where is common path distortion (CPD) typically most severe in a network?

Common path distortion (CPD) refers to a type of distortion that occurs when multiple signals travel through the same pathway in a network, often leading to interference and degradation of signal quality. It typically manifests in systems where the same transmission path is shared by multiple signals.

The output of a forward amplifier is a critical point in a network where CPD is most prominent. This is because the forward amplifier amplifies signals that have already gone through common pathways, making it susceptible to distortion from these signals. The amplification process can exacerbate any existing distortions due to the interaction of signals that share the same path, resulting in compounded effects as various frequencies interfere with one another.

In contrast, network entry points, drop systems, and customer premises may also experience some level of distortion, but they do not typically have the same concentrations of amplified signals and shared pathways that can lead to significant CPD. The output stage of an amplifier is where the effects of CPD become most pronounced, as it is the final stage before signals reach their intended destinations. Hence, the output of a forward amplifier is where you would expect to see the most severe common path distortion in a network.