Abstract

A digital optical serial communication system and encoding method comprises a transmitter responsive to an input of parallel information for parsing the information into 4-bit groups. The 4-bit groups are encoded into 5-bit codes having a 40/60 duty cycle and wherein no more than two consecutive bits are logical 1's or 0's on either end of the 5-bit code. The 5-bit codes are serially transmitted by an optical transmission medium for providing a conduit from the transmitter to a receiver. The receiver receives and decodes the serial information to 4-bit groups. The 4-bit groups are concatenated to form a parallel packet of information suitable for data processing. The encoding/decoding scheme has the advantages of (1) a worst case duty factor of 40/60%; (2) a maximum run of bits without transition equal to five; (3) an easily recaptured framing of packets due to a unique sync symbol; and (4) simple encoding and decoding of packets using combinational logic rather than lookup tables. In addition, data can be continuously sent via a communications protocol.

Other References

• ANSI.RTM. X3.148-1988, "American national Standard for Information Systems--Fiber Distributed Data Interface (FDDI)--Token Ring Physical Layer Protocol (PHY)," Computer and Business Equipment Manufacturers Association, American national Standards Institute, Inc. (1988