T 4.5 Cross-talk

Cross-talk is a special form of line impairment. In this case, the fault is not generally caused in the environment, but by currents and voltages of signals transmitted over adjacent lines. The intensity of this effect depends on the cable structure (shielding, cable capacity, insulation quality) and on the electrical parameters for information transmission (current, voltage, frequency).

Not every line affected by cross-talk will, in turn, necessarily have an effect on others. This phenomenon is encountered in the (analogue) telephone network. There, calls of other network participants can be heard. However, these often do not respond to the request "to clear the line" because cross-talk is confined to one direction. Checking one’s own lines for coupled-in, other-source signals does not yield any information on whether one’s own signals cause cross-talk in other lines and whether they can thus be monitored.

The main differences compared to other line faults is that, apart from disruption of signal transmission on adjacent lines, exploitable information may be available on other lines due to cross-talk.