User`s manual

Section 4: Configure Inputs, Part II - Calibration Coefficients
40
• Chelsea Aqua 3
Enter VB, V1, Vacetone, slope, offset, and SF.
Concentration (μg/l) = slope*[(10.0
(V/SF)
- 10.0
VB
)/(10.0
V1
- 10.0
Vacetone
)]
+ offset
where
VB, V1, and Vacetone are from calibration sheet
Slope (default 1.0) and offset (default 0.0) adjust readings to conform to
measured concentrations
Scale factor SF = 1.0 if CTD gain is 1; SF = 2 if CTD gain is 2.0
V is output voltage measured by CTD
Note: SEASAVE can process data for an instrument interfacing with up to
two Chelsea Aqua 3 sensors.
Chelsea Aqua 3 Example - Calculation of Slope and Offset
Current slope = 1.0 and offset = 0.0
Two in-situ samples:
Sample 1 –
Concentration (from SBE Data Processing) = 0.390
Concentration (from water sample) = 0.450
Sample 2 –
Concentration (from SBE Data Processing) = 0.028
Concentration (from water sample) = 0.020
Linear regression to this data yields slope = 1.188 and offset = - 0.013
• Chelsea UV Aquatracka
Enter A and B.
Concentration (μg/l) = A * 10.0
V
- B
where
A and B are from calibration sheet
V is output voltage measured by CTD
• Chelsea Minitracka
Enter Vacetone, Vacetone100, and offset.
Concentration = (100 *[V - Vacetone]/[Vacetone100 - Vacetone]) + offset
where
Vacetone (voltage with 0 µg/l chlorophyll) and Vacetone100 (voltage
with 100 µg/l chlorophyll) are from calibration sheet
• Dr Haardt Fluorometer - Chlorophyll a, Phycoerythrin, or
Yellow Substance
Enter A0, A1, B0, and B1.
These instruments may have automatic switching between high and low
gains. Select the gain range switch:
¾ Output Voltage Level if the instrument indicates gain by output
voltage level (< 2.5 volts is low gain, > 2.5 volts is high gain)
Low gain: value = A0 + (A1 * V)
High gain: value = B0 + (B1 * V)
¾ Modulo Bit if the instrument has control lines custom-wired to bits in
the SBE 9plus modulo word
Bit not set: value = A0 + (A1 * V)
Bit set: value = B0 + (B1 * V)
¾ None if the instrument does not change gain
value = A0 + (A1 * V)
where
V = voltage from sensor
Dr Haardt Voltage Level Switching Examples
Example: Chlorophyll a
Low range scale = 10 mg/l and Gain = 10/2.5 = 4 mg/l/volt
A0 = 0.0 A1 = 4.0
High range scale = 100 mg/l and Gain = 100/2.5 = 40 mg/l/volt
B0 = -100 B1 = 40.0
Note:
See Application Note 39 for complete
description of calculation of Chelsea
Aqua 3calibration coefficients.
Note:
See Application Note 61 for complete
description of calculation of Chelsea
Minitracka calibration coefficients.