Note, this applies to any PRR-800 Class instrument, including the PRR-800, 810, 2500, 2600 and GUV-2511
The formula used by the Logger software is :
(raw data in volts – dark offset) / scale factor = calibrated data in µW/cm2.
The GUV-2511 data is a little more complicated because each optical channel has three feedback resistors that are automatically selected by the firmware, depending on the input signal level. These three different feedback resistors help give the instrument its dynamic range. Because there are three feedback resistors, there are three dark offsets, one for each resistor, and also three scale factors.
All of the information needed by the software is in the various tables that make up the Access (.mdb) file. We have taken information from the data file
The first section is the raw data taken from the table for the 1 min period at 10:50:01 on 8/8/2010.
The next section is from the Resistor Table and shows which resistor was being used by each optical channel for the same time period. PAR is using Resistor 1, which is the small resistor; and 305 is using Resistor 3, which is the large resistor. All other channels are using Resistor 2, which is the medium resistor.
The third section is the channel table for your instrument and it contains the dark offsets (highlighted in yellow), and the scale factors (highlighted in orange) that correspond to the specific resistor (small, medium, or large) used by each channel during this 60 s period of data.
The final section is from the calibrated data table. If you click on the numbers in red, you will see the formula pointing to the individual raw data, offset, and scale factor used to derive the calibrated data.
If you want to collect data every second without averages, go to the Tools menu, select Options, then select the System Variables tab. You can adjust the data rate to 1 s and uncheck the box for Averaging Mode.