According to the earliest definition of wiring, it is divided into two types: unshielded cable-UTP and shielded cable-STP. Later, with the development of technology and different processes, many different types of shielding were derived. F/UTP Foil Screened Cable single-layer aluminum foil shielding structure. Foil and Braid Screened Cable aluminum foil and copper woven mesh double-layer shielding structure a ) SF/UTP aluminum foil and copper braid wrapped on the outer layer of four pairs of wires at the same time b) S/FTP (PIMF) wire to single pair aluminum foil shield plus copper braid wrapped on the outer layer of four pairs of wires PIMF = Pair in Metal Foil.
The shielded cable resists external interference mainly in: the integrity of signal transmission can be guaranteed by the shielding system. The shielded wiring system can prevent the transmitted data from being affected by external electromagnetic interference and radio frequency interference. Electromagnetic Interference (EMI) is mainly low frequency interference. Motors, fluorescent lamps and power lines are common sources of EMI. Radio frequency interference (RFI) is high frequency interference, mainly radio frequency interference, including radio, television broadcast, radar and other wireless communications.