Presentation Title

Calibration Changes

to the Pressure/Temperature Matrix

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Previous WVSSII calibration was not tailored to individual sensors, but rather used 16 different pre-generated matrices, selecting the one of 16 P/T matrices which most closely optimized senor output.

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Despite 2008 improved sensor electronics, the WVSSII performance at the factory and on NWS test stand was not performing to required standards.

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SSI conducted an analysis of the P/T calibration methodology and made the following changes:

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Software allows for calibration of non-linear values below 3,000 PPMV

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Improved accuracy of the P/T matrix mapping by using a single matrix tied to each sensor’s 3rd degree polynomial calibration coefficients

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Computed rather than stored P/T matrix.

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Advantage of P/T matrix is that the software is the same for every system with the only difference being in the coefficients of the terms of the equation.