Manchester encoding is used for 10BASE5, 10BASE2, 10BASE-T, FOIRL, 10BASE-FL, and 10BASE-FB.
For Manchester encoding, there is a voltage (or optical power) transition in the middle of each bit. At high speeds, this would produce a high-frequency signal.
For 100BASE-FX Ethernet and FDDI, each nibble is translated to a 5-bit code-group that has a sufficient number of 1-bits. Non return to zero inverted (NRZI) transmission is used. This means that 1-bits are trans-mitted by alternating between high and low optical power levels, but no power change occurs for a 0-bit.
For 100BASE-TX Ethernet and CDDI, each nibble is translated to a 5-bit code-group that contains at least two 1-bits. Each 1-bit is encoded as a step between three voltage ...