An overview of the Fiber-Optic Active Star Coupler program

The authors address issues surrounding the use of active rather than passive access couplers to provide connectivity for a large number of serial high-speed data bus (HSDB) users. The FOASC units being built will unite Westinghouse VHSIC avionic modular processors (VAMP) developed for the Air Force and incorporating HSDB interfaces designed and fabricated by the Harris Corp. The FOASC program consists of a detail requirements study for various aerospace platforms and HSDB configurations followed by the design, fabrication, characterization and test, and demonstration of FOASC units meeting the established requirements. The authors consider alternative configurations (topologies); bus architecture and specific aircraft issues; installation trade-offs, including power budget analyses; protocol issues, such as initialization behavior in the active star coupler environment; retiming requirements; fault-tolerance and redundancy trade-offs; and operational considerations. The design of the FOASC units includes a significant component development effort making possible a flexible, yet simple, low-power-consumption active star coupler. A test set specifically tailored to fully characterize FOASC performance has also been designed and built on this program. Performance characteristics of the FOASC units and test set are given