Section 2: Description of SBE 19plus V2
11
Specifications
Temperature
(°C)
Conductivity
(S/m)
Pressure
Measurement Range
-5 to +35 0 to 9
0 to full scale range:
• Strain-gauge sensor: 20 / 100 /
350 / 600 / 1000 / 2000 / 3500 /
7000 meters
• Quartz sensor: 20 / 60 / 130 / 200 /
270 / 680 / 1400 / 2000 / 4200 /
7000 / 10500 meters
Initial Accuracy
0.005 0.0005
• Strain-gauge sensor:
0.1% of full scale range
• Quartz sensor:
0.02% of full scale range
Typical Stability
0.0002/month 0.0003/month
• Strain-gauge sensor:
0.1% of full scale range/year
• Quartz sensor:
0.025% of full scale range/year
Resolution
0.0001
• 0.00005 (most oceanic water;
resolves 0.4 ppm in salinity).
• 0.00007 (high salinity water;
resolves 0.4 ppm in salinity).
• 0.00001 (fresh water;
resolves 0.1 ppm in salinity).
• Strain-gauge sensor:
0.002% of full scale range
• Quartz sensor:
0.0025% of full scale range for
NAvg=2 (Profiling mode) or
NCycles=2 (Moored mode);
(see notes below)
Sensor Calibration
(measurement outside these ranges
may be at slightly reduced accuracy
due to extrapolation errors)
+1 to +32
0 to 9; physical calibration over
range 2.6 to 6 S/m, plus zero
conductivity (air)
Ambient pressure to full scale range
in 5 steps
*Notes on Quartz Pressure Sensor Resolution:
Pressure Sensor Resolution = Sensitivity * Counter Resolution
• Sensitivity = Δ pressure / Δ frequency
where Δ pressure is change in pressure in desired units (psia, db, meters, etc.) = pressure sensor full scale range
Δ frequency is change in frequency in Hz ≈ 3000 Hz over sensor’s full scale range
• Counter Resolution = pressure sensor output frequency / (integration time * 1,843,200)
where pressure sensor output frequency ≈ 35,000 Hz
Integration time = 0.25 seconds
(requires NAvg= even number for Profiling mode; requires NCycles= even number for Moored mode)
• To convert pressure units: db = psia / 1.45
• Increasing NAvg= (Profiling mode) or NCycles= (Moored mode) reduces the measurement noise.
Example: What resolution can be obtained for a 7000 meter (10,000 psia) Quartz pressure sensor?
Sensitivity = Δ pressure / Δ frequency = 7000 m / 3000 Hz = 2.333 m / Hz
Counter Resolution = pressure sensor output frequency / (integration time * 1,843,200) = 35,000 Hz / (integration time * 1,843,200)
= 35,000 Hz / (0.25 seconds * 1,843,200) = 0.076 Hz
Resolution = Sensitivity * Counter Resolution = 2.333 db/Hz * Counter Resolution
= 2.333 db/Hz * 0.076 Hz = 0.18 db
≈ 0.18 m = 180 mm
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