Differential Manchester encoding is used for classical 4Mbps and 16Mbps Token Rings. It is described in the subsection that follows.
The encoding used for 100Mbps Token Ring is identical to that used for 100BASE-X Ethernet. This helped Token Ring vendors roll out products quickly and kept costs down through reuse of existing components.
Differential Manchester encoding is a variation on the Manchester encoding used for 10Mbps Ethernet LANs. It is used for 4Mbps and 16Mbps Token Ring LANs.
Bits are represented using transitions between high and low voltages for twisted-pair cabling, or high and low light levels for optical fiber.
For a 0, there are transitions at both the beginning and the middle ...