Twisted cable is formed by twisting a pair of mutually insulated metal wires. In this way, it can not only resist a part of electromagnetic wave interference from the outside, but also reduce the mutual interference between multiple pairs of twisted wires. The two insulated wires are twisted together, and the interference signal acts on the two wires that are twisted together. The interference signal is called the common mode signal. The common mode can be used in the differential circuit of the received signal. The signal is eliminated to extract the useful signal (differential mode signal).