Calibration equations and cross-channel dependencies
In the following section, the various equations available in the instrument are described. Some equations applied to a channel are straightforward (like the linear equation or the temperature equation). Others might refer to other channel readings (cross-channel dependencies) to correct various physical effects (for example, conductivity with pressure and temperature correction). Others are for purely derived channels (for example, the derivation of practical salinity).
For each equation, the following will describe the coefficients used (c and x group of parameters of the calibration command) and the cross-channel dependencies required (n group of parameters of the calibration command).
The primary input to most equations is the raw reading of the channel (sometimes referred to as R, a raw number normalized to a nominal full scale of 1). This is typically a binary reading from an A/D converter divided by a full-scale value of 230, and so is often referred to as a “voltage ratio”. It might also be an internally normalized reading of a digital sensor (external or internal).