The 100Base-TX standard is a method in which the data is transmitted via two UTP cables ofcategory 5 (cat 5). The transmit data is transmitted over one pair of wires, the receive data over the second.
In contrast to the classic Ethernet with 10 Mbit/s, 100Base-TX does not work with Manchester coding, but with 4B5B coding. The line coding is selected in such a way that there is at least one level change for synchronization within a 5-bit word. This increases the transmission rate from 100 Mbit/s to a frequency of 125 MHz. Using Multi Level Transmission( MLT-3), in which 4 bits are transmitted in three levels, the transmission frequency is reduced to a quarter, i.e. 31.25 MHz.
Scrambling the frequencies results in a more uniform frequency spectrum. As a result, the American interference radiation conditions according to FCC Class B rules and also the European regulations according to EN 55022B for EMC are complied with. The connection technology depends on the transmission medium: UTP cables use the RJ45 connector, STP cables use the Sub-D connector.
The basic idea of 100Base-TX is based on the use of FDDIPMD, whereby the CSMA/ CD process is retained. 100Base-TX is used in automation and automotive technology, for example in BroadR-Reach and Diagnostics over IP( DoIP).