Version 3.0.1 of Profiler for PRR-800 class instruments has now been released. This version incorporates commands to allow the optical channels to be "zeroed" at each of the three gain settings present in their data acquisition system. This change is made in response to suggestions from Dr. S. Hooker of NASA to be able to use these instruments in the most effective way possible, which is particularly important in working in shallow waters. Such zero corrections are normally made at the factory during calibration or recalibration, but now the user has the ability to do this in the field when the instrument is in a temperature regime similar to its field operating conditions.
Note, if you are a user of the older "PRR-600" or similar instruments, then this software is NOT for you because its design is different and does not have multigain stages. The last stable version released for older instruments was version 1.5.17. Note that there were no versions between these released, and version 2 was skipped entirely because of a desire to consolidate all DLL files under a consistent numbering scheme.
Note also, if you are using a new “uRadiometer”–based instrument, like C-OPS, then uProfile already has this ability included so no update is required.
It is also important to note that there are minor changes made to the calibration database that is used with the instrument. For that reason, we recommend that you switch to the newer software after you have a factory recalibration. If you would like to use this software immediately, please send an e-mail to email@example.com asking for a new calibration database containing your latest calibration data in the new format.
Dark Offset Correction Procedure
- Power on the instrument and let it stabilize for approximately 5 minutes (black instruments covered, in the shade, out of the Sun so they do not heat up).
- Start Profiler and use the ORIGINAL calibration file provided by Biospherical Instruments (or whoever conducted the most recent calibration).
- Set the sampling rate (Tools\Options\System Variables) to the rate you want to use for data collection.
- Carefully put on the dark caps and cover the irradiance and radiance sensors. NOTE: A black cloth is not enough! Be certain that the in-water sensors do not heat up from sitting in the Sun. Do not put the profiler into the water!
- Now that the instrument is connected and has been on for 5 minutes, and ideally, close to operating temperature (i.e., not baking in the Sun), use the menu option "Tools/Measure Dark Offsets" to start the process
- If you cannot access all the sensors (the Ed0 sensor may be up on a mast, for example), choose the ones that are dark, and Start Dark Measurements (at 10 Hz sample rate this will take around 6 minutes).
- Press the button to save the offsets and tare the underwater pressure transducer. The resulting file name will look something like “2011_02_18_2300_OFFSETS.mdb” where the date and time are combined with "OFFSETS" to designate that this file contains new offset values.
- The software will now exit to Windows and needs to be restarted.
- Restart the software. Connect to the instrument using the OFFSETS MDB file you just created as a calibration source. You will be ready to record a new data file at this point. This data file will be identical to the files you have created in older versions of Profiler, but there will be two new columns in the Channel table: ScaleCal, and OffsetCal. The ScaleCal column will contain the name of the files used in step 1, and the OffsetCal column will contain the name of the file created in step 7, at least for the channels whose offsets were kept. Note that offsets for Temperature and for diagnostic channels are not transferred to the channel table and the entries in these cells should reflect the original cal file name from step 1.
- Additional data files can select either the offset file created in step 7, or any subsequent data file created from the new OFFSET file.
A final reminder: the depth that is reported will still need correcting for the physical offset between the actual location of the pressure transducer and the radiance and irradiance sensors. Also, you should look at the calibration data for the pressure sensor for details on the density assumed in the computation of "depth" from pressure.
You may download the software here.