High levels of ingress noise enter a CATV system through damaged or otherwise improperly shielded coaxial cable or related components. Ingress can reduce signal quality and prevent an effective installation.

Upstream Spectrum measurement mode views and analyzes ingress and distortion on the upstream path (return path). It identifies the frequency at which ingress occurs and displays the level value. This level measurement can be checked in relation to a user-configured limit to determine a pass or fail status. Test results can be stored for later reference.

Initial measurements typically occur at the ground block with the home disconnected from the network. Prior to an installation, use upstream spectrum measurements to verify that the system does not exceed the maximum acceptable level for ingress noise. After an installation, check the noise level again to compare the previous reading and confirm that install procedures or components did not create new sources of ingress noise.