interference
Signals that occur unintentionally as stray signals due to capacitive, inductive or galvanic coupling on the lines are called interference signals. Interference signals are generated on the one hand by crosstalk between neighboring lines, and on the other hand by external EMC influences. Interfering signals impair the received signal behavior; for this reason, one tries to prevent or reduce these signals and, above all, their radiation, by means of specific cable construction.
With shielded cables, however, the external influence is so small that it can be neglected. With unshielded cables, however, adjacent signal lines can have an additional negative influence on the attenuation crosstalk ratio( ACR).
With unbalanced cables, such as coaxial cables, one or more shields dissipate the interference via the shielding. In balanced, unshielded UTP cables, the interfering signals are compensated by a completely symmetrical cable construction. The structure of the cores is selected in such a way that interfering signals interspersed by the cable stranding occur on both cables with the same strength and the receiver only receives the difference of the interfering signals.
The interfering signal originates on the one hand from the crosstalk of neighboring lines and on the other hand from EMC influences from outside. With shielded cables, however, the external influence is so small that it can be neglected. With unshielded cables, however, neighboring signal lines can have an additional negative influence on the ACR ratio.