The Fly-by-Light Advanced Systems Hardware (FLASH) program developed Fly-by-Light technologies for flight control and vehicle management of military and commercial aircraft. The FLASH program established requirements, performed a trade study, and selected the Dual Rate AS1773 fiber-optic data bus as the baseline interconnection means between equipment designed, built, and demonstrated by FLASH team-mates. This paper cites the lessons learned in using the AS1773 data bus. This includes the individual problems that users experienced and the overall problems of working with immature data bus components.
The Fly-by-Light Advanced Systems Hardware (FLASH) program is developing Fly-by-Light technologies for flight control and vehicle management of military and commercial aircraft. Fiber optics offers greatly improved data transfer rate, very low susceptibility to electromagnetic interference (EMI), lower on-board weight, and lower operating and maintenance costs. FLASH will result in demonstrations needed to gain confidence in using Fly-by-Light for flight control and vehicle management. This paper reviews the requirements and the trade study leading to selection of the dual-rate 1773A fiber optic data bus to interconnect fly-by-light advanced system hardware.
KEYWORDS: Digital signal processing, Charge-coupled devices, Signal processing, Video, Clocks, CCD cameras, Cameras, Data conversion, Mirrors, Data processing
An experimental examination of the suitability of using a CCD imaging sensor for space lasercom applications was conducted. A specialized CCD camera capable of operating in high rate partial frame mode for tracking as well as normal rate full frame mode for acquisition was built. CCD pixel rate is 7.5 MHz. A flash A/D digitizes the pixel signals and inputs them to a 30 MIPS digital signal processor which processes the input data between pixels. The processor inputs the pixel magnitude, compares it to the previous brightest pixel in the frame, saves it to memory, remembers its location and magnitude if it is brighter than the previous brightest pixel, and then inputs the next pixel.
Trade studies and close examination of direct detection laser crosslinks for a number of applications have shown that the development risk is comparable to or lower than that of RF systems. Since laser crosslinks offer significant advantages over RF crosslinks for the same applications, the specification of laser crosslinks is a good choice. The reason that the risk is low is examined in this paper which details the technologies and components which comprise current, second generation design laser crosslinks. The specifics which are examined include diode power summing, diode life, data rates of a Gbps and beyond, detector sensitivity/radiation effects, telescopes, gimbals and optics, alignment stability, acquisition, pointing and tracking, electronics and the space qualification of assemblies and systems. Differences between first and current (second generation) system designs and technologies are examined. An assessment of the maturity of the current direct detection technology is made and conclusions formulated.
Quadrant avalanche photodiodes (QAPDs) cannot be made with a perfect transition region. We are pursuing development of several optical divider approaches to narrow the effective transition region of the RCA Juction-side divided QAPD, a superior device except that it has no response in the transition region. This divider will maximize the slope factor and minimize optical losses. Optical divider approaches include the total internal reflection prism divider, the etched silicon reflective divider, and the binary optics quadrant divider. The nature and progress of this work and the test results are reported.
We designed and built a full duplex atmospheric optical communication link to convey video and audio signals at ranges up to 1 mile. We used an active tracking system to point each terminal at the other. This paper describes elements of the design and discusses test results.
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