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  • 1
    Publication Date: 2016-06-07
    Description: Installed fibers such as those at the Kennedy Space Center (KSC) are optimized for use at 1310 nm because they have zero dispersion at that wavelength. An installed fiber system designed to operate at 1310 nm will operate at a much lower data rate when operated at 1550 nm because the dispersion is not zero at 1550 nm. Using dispersion measurements of both installed and dispersion compensating fibers, we compensated a 21.04 km length of installed fiber with 4.25 km of dispersion compensating fiber. Using the compensated fiber-optic link, we reduced the dispersion to 0.494 ps/nm-km, from an uncompensated dispersion of 16.8 ps/nm-km. The main disadvantage of the compensated link using DC fiber was an increase in attenuation. Although the increase was not necessarily severe, it could be significant when insertion losses, connector losses, and fiber attenuation are taken into account.
    Keywords: Optics
    Type: NASA/ASEE Summer Faculty Fellowship Program; 133-142; NASA-CR-202756
    Format: application/pdf
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  • 2
    Publication Date: 2016-06-07
    Description: Optical fibers represent the back bone of the current communications networks. Their performance in the field lacks long term testing data because of the continuous evolution of the manufacturing of fibers and cables. An optical fiber cable that is installed in NASA's KSC has experienced a dramatic increase in attenuation after three years of use from 0.7 dB/km to 7 dB/km in some fibers. A thorough study is presented to assess the causes of such an attenuation increase. Material and chemical decomposition testing showed that there are no changes in the composition of the fiber which might have caused the increase in attenuation. Microbending and heat cycling tests were performed on the cable and individual fibers. It was found that the increase in attenuation is due to microbending caused by excessive stress exerted on the fibers. This was the result of manufacturing and installation irregularities.
    Keywords: Optics
    Type: NASA/ASEE Summer Faculty Fellowship Program; 1-10; NASA-CR-202756
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-18
    Description: The brightness signal from a pressure-sensitive paint varies inversely with absolute pressure. Consequently high signal-to-noise ratios are required to resolve aerodynamic pressure fields at low speeds, where the pressure variation around an object might only be a few percent of the mean pressure. This requirement is unavoidable, and implies that care must be taken to minimize noise sources present in the measurement. This paper discusses and compares the main noise sources in low speed PSP testing using the "classical" intensity-based single-luminophore technique. These are: temperature variation, model deformation, and lamp drift/paint degradation. Minimization of these error sources from the point of view of operation in production wind tunnels is discussed, with some examples from recent tests in NASA Ames facilities.
    Keywords: Nonmetallic Materials
    Type: 6th Annual Pressure Sensitive Paint Workshop; Oct 06, 1998 - Oct 10, 1998; Unknown
    Format: text
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  • 4
    Publication Date: 2019-07-13
    Description: System of multimode fiber-optic communication links upgraded to enable simultaneous communication on two channels in each fiber. Incorporates two-wavelength-division multiplexing at both ends of each fiber so two signals transmitted, either in same direction or in opposite directions.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: KSC-11732 , NASA Tech Briefs (ISSN 0145-319X); 20; 6; P. 10a
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