OK, so we add a bunch of new channels to the network, digital video and audio, and perhaps even cable modem service. Some of these new services are interactive, which requires a two-way network. Maintaining a two-way cable system so that it provides reliable interactive services means we have to pay attention to system maintenance. Good maintenance starts with time-proven practices such as system sweeping, a process where network amplifiers and other devices are aligned using broadband sweep equipment to ensure flat frequency response and correct operating levels. Another important task is maintaining signal leakage at levels well-below government requirements.
Leakage also is known as egress.
One of the most misused leakage-related terms is cumulative leakage index, or CLI, which is not the same as signal leakage. It s a figure of merit that provides a snapshot of sorts of the magnitude of a cable system s signal leakage. If a cable system has signal leakage problems, it also will have ingress problems. Ingress is the opposite of egresss. The signals must be converted from their original baseband form to RF, using a technique called modulation.