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Sondes Section 2
YSI Incorporated Drinking Water Monitoring Systems Operations Manual 2-62
Sampling Faster Than 0.5 Seconds
For special applications, your sonde is capable of faster sampling. The only limitation is a reduction of the
number of sensors selected. To determine the maximum sampling frequency for your sensor setup, divide
36 by the number of enabled sensors in addition to the free chlorine sensor.
Example:
If you enable any three sensors plus DO, divide 36 by 3 to obtain 12 samples/second (12 Hz) or 0.083
seconds between samples as the maximum sampling frequency. Remember that for sample intervals less
than 4 seconds, free chlorine readings are updated only every 4 seconds. Thus, at 12 Hz, the display will
show 48 identical Cl2 readings before a change occurs. Note also that at a faster sampling rate, consecutive
readings are closer together, the threshold for any one sensor is less likely to be exceeded, and the data
filter is less likely to disengage. For these applications you may want to adjust your threshold settings
accordingly. See Section 2.9.8 for more information on the data filter.
Select 3-File to enter a filename with a maximum of 8 characters. You will log readings to the filename
that you enter.
If you started sampling without entering a filename, the default name NONAME1 will be assigned to your
file. Whenever you press
1-LOG last sample or 2-LOG ON/OFF from the menu, NONAME1 will be
opened during sampling. If this happens, and you want to restart the file with a different name, press 5-
Close file and rename the file.
Select
4-Site to assign a site name with a maximum of 31 characters This allows you to enter the name of
the site where you are sampling.
When you select 5-Open File , a file is opened and the number 5 changes to Close File . When you are
finished logging data to the file, press 5-Close File and designation changes back to Open File . When you
start logging the Open File designation changes automatically to Close File .
Now select
1-Start sampling to start discrete sampling.
After the initial sampling time interval has passed, sequential lines of data will appear on the screen and
you can log single or sequential data points and wipe the surface of your optical probe as described above.
UNATTENDED SAMPLING
This option is used for long-term deployment of the battery-powered sonde when the user is not present at
the site. Prior to this selection, the sonde is usually attached to a computer in a laboratory and set up to
automatically log data to sonde memory at a fairly long time interval (15-60 minutes). The unit is then
taken to the field site and left for an extended time period (30 – 60 days). When the study is complete, or
the batteries are expended, the unit is brought back to the laboratory and the data file is uploaded to a
computer. Quality assurance checks are performed prior to redeployment.
Select
2-Unattended Sampling from the Run menu. The Unattended sample menu will be displayed. Use
the following example to understand the unattended sampling option.