How Twisting the Cables Reduce the Interference?

Twisting the cables is done to remove the electromagnetic interference from the wires. When a signal is transmitted through the cable it is in the form of current. This flow of current produces an electromagnetic field of interference around it and can generate noise effects in the surrounding cables. One pair can induce cross-talk in another and it is additive along the length of the cable.


Thus in order to eliminate this twisted wire approach is used. Under this scheme, the wires twisted with and along each other carry equal and opposite amount of current through them. Therefore, the interference/noise produced by one wire is cancelled by the interference/noise produced by other wire since they are equal and opposite in nature. All the charges and forces balance out each other in order to get a hindrance free and pure signal output without any disturbances.

Advantages:
  • Electrical noise going into or coming from the cable can be prevented.
  • Cross-talks is minimized.


Disadvantages:

  • Twisted pair’s susceptibility to electromagnetic interference greatly depends on the pair twisting schemes staying intact during the installation. As a result, twisted pair cables usually have stringent requirements for maximum pulling tension as well as minimum bend radius.
  • In analog video applications that send information across multiple parallel signal wires, twisted pair cabling can introduce signaling delays known as “skew in twisted cables” which cause subtle color defects and ghosting due to the image components not aligning correctly when recombined in the display device. Thus it causes delay lines in output.

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