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

Common path distortion (CPD) primarily occurs at the output of a forward amplifier. This is due to the nature of how amplifiers operate within a network. Amplifiers are used to boost the signal strength to overcome losses that occur within the transmission medium. However, the amplification process can introduce various distortions due to nonlinearities in the amplifier's characteristics.

As the signal passes through an amplifier, different frequencies may be amplified unevenly, leading to phase shifts and amplitude differences among signals. These disparities manifest as distortion in the transmission path. Therefore, the output of the forward amplifier, where the amplified signals are sent out into the distribution network, becomes a critical point where CPD may significantly affect the overall signal quality and integrity. This makes it a focal area for diagnosing and mitigating distortion-related issues in network performance.