User`s manual

Section 4: Configure Inputs, Part II - Calibration Coefficients
45
Oxygen Calibration Coefficients
Enter the coefficients, which vary depending on the type of oxygen sensor,
from the calibration sheet:
• Beckman- or YSI-type sensor (manufactured by Sea-Bird or other
manufacturer) - These sensors require two channels - one for oxygen
current (enter m, b, soc, boc, tcor, pcor, tau, and wt) and the other for
oxygen temperature (enter k and c). Make sure to select both when
configuring the instrument.
Note: SEASAVE can process data for an instrument interfacing with up to
two Beckman- or YSI-type oxygen sensors.
• IOW sensor - These sensors require two channels - one for oxygen
current (enter b0 and b1) and the other for oxygen temperature (enter a0,
a1, a2, and a3). Make sure to select both when configuring the instrument.
Value = b0 + [b1 * (a0 +a1 * T + a2 * T
2
+ a3 * T
3
) * C]
where
T is oxygen temperature voltage, C is oxygen current voltage
• Sea-Bird sensor (SBE 43) -
This sensor requires only one channel. Enter Soc, Boc, Voffset, tcor, pcor,
and tau.
OX
=
[Soc*{(V+Voffset)+(tau*δV/δt)}+Boc*exp(-0.03T)]*exp(tcor*T+pcor*P)*Oxsat(T,S)
where
OX = dissolved oxygen concentration (ml/l)
T = measured temperature from CTD (ºC)
P = measured pressure from CTD (decibars)
S = calculated salinity from CTD (PSU)
V = temperature-compensated oxygen signal (volts)
δV/δt = derivative of oxygen signal (volts/sec)
Oxsat(T,S) = oxygen saturation (ml/l)
Note: SEASAVE can process data for an instrument interfacing with up to
two SBE 43 oxygen sensors.
Notes:
• Enter soc and boc values from the
most recent field calibration for
Beckman-type, YSI-type, or
Sea-Bird (SBE 43) oxygen sensor.
• See Application Notes 13-1 and 13-3
for complete description of
calculation of calibration coefficients
for Beckman- or YSI-type sensors.
• See Application Notes 64 and 64-2
for complete description of
calculation of calibration coefficients
for the SBE 43.
• Oxygen values computed by
SEASAVE and SBE Data
Processing’s Data Conversion
module are somewhat different from
values computed by SBE Data
Processing’s Derive module. Both
algorithms compute the derivative of
the oxygen signal with respect to
time, with a user-input window size
for calculating the derivative:
¾ Quick estimate -
SEASAVE and Data Conversion
use a window looking backward in
time to compute the derivative,
because they share common
code and SEASAVE cannot use
future values while acquiring
real-time data.
¾ Most accurate results -
Derive uses a centered window
(equal number of points before
and after scan) to compute
the derivative.
The window size is input on
Configure Inputs’ Miscellaneous tab.