High-reliability optical fiber local area networks for aircraft applications

We describe the high-reliability military airborne optical fiber local area network (MAOF-LAN). Since light-emitting diodes (LEDs) have better temperature performance and require less complex driver circuit than laser diodes, the former is normally chosen as an optical source in the severe aircraft environment. In this case, the optical power budget becomes a critical factor which greatly limits the number of terminals in a MAOF-LAN. In order to solve effectively this problem and to ensure the high reliability, we present the active-coupler configurations using PINs and LEDs for a MAOF-LAN. The topologies are discussed, and the system design is described. An efficient modulation technique-Partial Trilevel Manchester II Bi-phase Coding is presented to greatly reduce the complexity of optical transceivers and the processing time at receivers compared to using the MIL-STD-1773 modulation scheme