corr_cond3 - conductivity with pressure and temperature correction

The conductivity reading from the conductivity channel without corrections is given by a simple linear function:

where R is the normalized voltage ratio from the channel monitoring conductivity, c0, c1 are the core coefficients of the linear equation, along with c2 which is a geometrical factor (K-factor) reflecting the final installation of conductivity cell, and Craw is the uncorrected conductivity output, reported in mS/cm for RBR marine instruments.

The equation which corrects the output for the effects of both temperature and pressure on the conductivity cell is:

Casting the equation into the style used by the logger would give:

where

• Craw is the uncorrected conductivity, c0  +  c1 × c2 × R.

• x0, x1 correspond respectively to the temperature compensation constants "Kc1", "Kc2".

• x2, x3, x4 correspond respectively to the pressure compensation constants "Kp1", "Kp2", "Kp3".

• x5 is the calibration temperature "Tcal" in °C.

• x6 is the calibration pressure "Pcal" in dbar.

• n0 is the label of the internal temperature of the conductivity cell channel in °C, in the examples conductivitycelltemperature_00.
  value(n0) is the final output value of the internal temperature of the conductivity cell channel in °C.

• n1  is the label of the pressure channel, in the examples pressure_00.
  value(n1) is the final output value of the pressure channel in dbar.

• Ccorr is the corrected output in mS/cm. 

It is quite common to have a logger monitoring conductivity and temperature without a pressure channel, typically deployed at a known, constant depth. In this case, n1 would be set to "value", and so value(n1) would be substituted by a default value (see the "parameters pressure" command).

Examples

>> calibration conductivity_00 datetime=20251001000000 c0=0.2346 c1=153.4873 c2=1.0001

Set the core coefficients.

>> calibration conductivity_00 datetime=20251001000000 x0=0.2003 x1=0.2943 x2=0.005 x3=0.085 x4=0.0001 x5=15.0280 x6=10.0025

Set the cross-channel correction coefficients.

>> calibration conductivity_00 
<< calibration conductivity_00 datetime=20251001000000 equation=corr_cond3 offset=0.0000000e+000 slope=1.0000000e+000 c0=16.552176e-003 c1=157.61278e+000 c2=1.0000000e+000 x0=0.0000000e+000 x1=0.0000000e+000 x2=0.0000000e+000 x3=0.0000000e+000 x4=0.0000000e+000 x5=0.0000000e+000 x6=10.000000e+000 n0=conductivitycelltemperature_00 n1=pressure_00

Request confirmation of all calibration coefficients.