User Manual for AML Oceanographic’s Micro Pressure Sensor
AML OCEANOGRAPHIC
In-situ Real-time Detection Measurement
15
5 CALIBRATION
The Micro Pressure Sensor sensor must be calibrated occasionally. The pressure sensor was
calibrated at the factory at the time of manufacture. This should remain within published
specifications for periods of 1 - 2 years, depending on the amount of use, depth of
deployment, and other conditions occurring in the deployment environment. Sensor
accuracy is also dependent upon proper care and maintenance by the user. Re-calibration of
these sensors must be done at the factory.
The sensor is calibrated by recording the instrument's raw data to known reference points at
different temperatures. This data is applied to a curve fitting algorithm to produce
calibration coefficients for both pressure and temperature effects. Each set of coefficients is
permanently stored in the instrument's memory.
Calibration coefficients are not interchangeable. Each set is unique to each instrument. The
calibration coefficients for the instrument to which this manual belongs are listed on the
‘
Customer Documentation CD
’ sent with the instrument. The user will need these
coefficients if the instrument is to be used in the RAW mode for post processing purposes.
5.1 Theory
The pressure electronics use the following formula to convert raw data to engineering units
(dbar):
P = A+B*Npt+C*Npt
2
+D*Npt
3
+(E+F*Npt+G*Npt
2
+H*Npt
3
)*Np+(I+J*Npt+K*Npt
2
+L*Npt
3
)*Np
2
Where: P = pressure in dBar.
Npt, Np = raw values
A through L are calibration coefficients determined at the factory
