Sea-Bird Electronics SBE 38 Manual de usuario descargar pdf (Pagina 11)

Manual revision 006 Section 2: Description of SBE 19plus V2 SBE 19plus V2

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:

0.02% 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

Real-Time Clock

32,768 Hz TCXO accurate to ±1 minute/year

Memory

64 Mbyte non-volatile FLASH memory

Data Storage

Recorded Parameter Bytes/sample

Temperature & Conductivity 6 (3 each)

Strain-gauge or Quartz Pressure 5

each external voltage 2

SBE 38 secondary temperature 3

WET Labs RS-232 sensor 6

each Pro-Oceanus GTD 4 (pressure) + 3 (temperature)

Aanderaa Optode 3

date & time (Moored mode only) 4

*Notes on Quartz Pressure Sensor Resolution:

Pressure Sensor Resolution = Sensitivity * Counter Resolution

• Sensitivity = ∆ pressure / ∆ frequency

where ∆ pressure is change in pressure in desired units (psia, db, meters, etc.) = pressure sensor full scale range

∆ 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 = ∆ pressure / ∆ 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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Sea-Bird Electronics SBE 38 Manual de usuario Pagina 11

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