Instructor Note   As with all LAN technologies, a signaling method must be chosen. The most common varieties of Ethernet use Manchester encoding (though the newer, faster varieties use more complex encoding schemes). Again, the point for the students is that a particular technology has a particular way of putting signals on the medium.

Signal encoding is a way of combining both clock and data information into a stream of signals over a medium.  The rules of Manchester encoding define a 0 as a signal that is high for the first half of the period and low for the second half. It defines a 1 as a signal that is low for the first half of the period and high for the second half. 

10BASE-T transceivers are designed to send and receive signals over a segment that consists of 4 wires - 1 pair of wires for transmitting data, and 1 pair of wires for receiving data. 

Note: Manchester encoding results in 0 being encoded as a high-to-low transition and 1 being encoded as a low-to-high transition. Because both 0's and 1's result in a transition to the signal, the clock can be effectively recovered at the receiver.