【文章內(nèi)容簡介】 e on the bus without causing disruption. A system configuration diagram of the fiber optic bus system is shown in Figures 3 and 4. Figure 3 illustrates the system with two lowspeed FOIUs singled out, while Figure 4 depicts what could be the same system, but with the high speed test set specifically illustrated. Figure 4. Fiber Optic Bus Configuration Showing HighSpeed Test Set Demonstration System Fiber Optic Bus Hardware The demonstration system fiber optic bus structure was realized using readily available fiber optic ponents. A single bus structure was made up of connector fiber optic cables and a 1616 port transmissive star coupler (expansion to a 32 port coupler is also considered to he feasible). The FOIUs housed optical transmitters, optical receivers, lowspeed logic and levelshift circuit boards, and where employed, the highspeed transmitter and receiver logic. In addition the units contained their own power supplies. These units were mounted on the exterior cabiry of user equipment being demonstrated, and hooked directly into the 1553B I/O connector. Each FOIU contained two logic boards, each serving one of the dualredundant channels. Circuits were realized using Small Scale Integrated TransistorTransistor Logic (SSI 39。ITL) logic chips and discrete ponents. Mounted on each of these boards was an optical transmitter and an optical receiver. Translation of this design to smaller versions such as a single SEME Module is feasible. The optical transmitter chosen for this application was a highradiance light emitting diode (LED).The diode was operated at less than full output, launching dBm (average) optical power into 100 micron core fiber. The dual speed optical receiver was packaged in a module measuring 3 for mounting onto the logic and levelshift board. This burstcapable device, developed by ATamp。T, as a sensitivity of approximately 34 dBm (average) for 10 39。 Bit Error Rate (BER), and uses a simplified edge detection technique. Highly stable operation over a temperature range from 55176。C to +85℃ has been demonstrated. The fiber optic cable assemblies were fabricated using lengths of avionic fiber optic cable connectorized with the ATamp。T biconic connector. The cable contains 1001140 micron graded index fiber, and has been used in production AVS/B Harrier Ⅱ fighter aircraft. Commercial 1616 port transmissive star couplers installed with biconic couplers were purchased. The input to output port loss exhibited by the star coupler was dB177。5 dB of loss. Highspeed Test Set The highspeed test set was designed to prove the feasibility of the MSDRT Concept. As the avionics used in the bus demonstration system consisted only of lowspeed equipment associated with the 1553B bus, a tester was designed to exercise the highspeed FOIUs. The test set consists of an FOIU c