3.7 Correlation Cell Pressures
The correlation cell pressures will enter into the performance computations in two ways:
3.7.1 Correlation Cell Pressure Stability
The stability of the correlation cells in temperature and pressure must be such that the
required precision of measurement can be maintained between calibrations. In the worst case
this implies that fractional stability should be on the same ratio as the ratio of the difference
signal to the sensitivity.
3.7.2 Correlation Cell Pressure Knowledge
The knowledge of the correlation cell pressures is less stringent than the required precision
because most of the error is removed in the calibration operation. The remaining error
influences the shape and altitude of the weighting function in the case of the thermal
channels and the sensitivity to column amount in the case of the column channels.