Two pairs of twisted wires are used. One is used for receiving data and the other is used for transmitting data. The recommended maximum lobe length for UTP when using a passive concentrator is 100 meters. This length can be doubled when using an active re-timing concentrator. Only one station in the entire ring transmits using its own crystal clock.
Signal flows only in one direction.
The signal distortion introduced by the channel is compensated by equalization. A-4 shows a typical physical layer schematic on a NIC or at an active concentrator's lobe port. Some amount of pre-distortion is introduced by the transmit filter to compensate for channel distortion. Equalization is also done in the receiver. This may either be implemented as a fixed equalizer or can be done adaptively.