Calibration processing for the infrared channels takes place at the CDA in real time. In the processing, the calibration coefficients are computed and are applied to the raw data, converting them to radiances, as previously discussed. The radiances are scaled linearly so that they utilize the full 10-bit (imager) or 16-bit (sounder) word length of the GVAR. The calibration coefficients (three per channel/detector) and the scaling coefficients (two per channel) are also transmitted in the GVAR. Users can derive the radiances from GVAR counts by inverting the scaling operation. The procedure for converting GVAR counts to radiances, temperatures, and eight-bit "mode-A" counts¹⁵ is described in detail in Appendix A. For the sounders, the GVAR will contain both radiances and raw data. For the imagers, it will only contain the radiances, because the GVAR does not have enough bandwidth for both. The GVAR also contains statistical data and telemetry information for monitoring the calibration and instrument performance.

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