Sea-Bird Electronics SBE 38 Bedienungsanleitung PDF herunterladen (Seite 14)

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

Sample Timing (Moored Mode)

Sample timing in Moored Mode is dependent on a number of factors, including

the 19plus V2 pressure sensor type – strain gauge or Quartz, setup for the pump

(MooredPumpMode=), and user-programmable sampling parameters for

number of samples per measurement (NCycles=) and delay before sampling to

allow time for auxiliary sensors to stabilize (DelayBeforeSampling=).

For autonomous sampling (logging), the 19plus V2 requires a minimum of

5 seconds from the end of one sample to the beginning of the next sample. After

it takes each sample, it checks the time for the start of the next sample, based on

the user-programmable sampling interval (SampleInterval=). If there is less

than 5 seconds remaining until the programmed start of the next sample, the

19plus V2 provides a message:

Error - - > alarm time not far enough in the future,

resetting alarm to 5 sec from now

The 19plus V2 takes the next sample in 5 seconds. The 19plus V2 performs this

check after each sample; because of small variations in sampling time, this can

cause samples to be taken at uneven intervals. Therefore, best practice is to

check the sample timing before you set up the instrument, to ensure that the

sample interval is long enough.

Examples are shown below:

Example 1 - pump on for 0.5 sec before each sample

(MooredPumpMode=1)

, strain gauge pressure sensor,

1 measurement/sample (NCycles=1):

Sampling time = 0.5 sec (pump before sampling) + 2.5 sec (basic sampling time for strain gauge) = 3.0 sec

Minimum sample interval (SampleInterval=) = 3.0 sec + 5 (sec between samples) = 8.0 sec < 10 sec minimum,

so minimum SampleInterval=10.

Example 2 - pump on during sample (MooredPumpMode=2), 15 sec delay before sampling (DelayBeforeSampling=15),

Quartz pressure sensor, and 4 measurements/sample

(NCycles=4):

Sampling time = 15 (delay before sampling) + 2.45 (basic sampling time for Quartz) +

(4 – 1) * 0.25 (additional measurements/sample for NCycles) = 18.2 sec

Minimum sample interval (SampleInterval=) = 18.2 sec + 5 (sec between samples) = 23.2 sec,

so minimum SampleInterval=25 (round up by a few seconds, to account for any small differences in sample timing).

Notes:

• See moored mode sampling times

in Specifications.

• Sample timing information is

approximate.

• See Battery Endurance for power

limitations.

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Sea-Bird Electronics SBE 38 Bedienungsanleitung Seite 14