Using the 10 and 20 cm Survey Chambers
6-21
The LI-8100A software uses the Chamber Offset and the Soil Area values to
calculate the volume of air inside of the soil collar. This value is, in turn,
added to the Chamber Volume to obtain the Total System Volume.
Measuring the Chamber Offset is described in Section 2, Using Soil Collars.
Soil Area
The area of soil encompassed by the soil collar, in cm
2
. Calculate the Soil
Area from the inside diameter of the soil collar. The default values in the
LI-8100A software are given for the 10 cm and 20 cm soil collars provided by
LI-COR.
Chamber Volume
The Chamber Volume value includes the air inside the chamber, as well as
from the tubing attached to the chamber. This volume is entered
automatically when you choose the Survey or Long-Term chamber in
software, but can be adjusted manually by the user if the chamber volume
changes for any reason (i.e., the tubing length changes).
IRGA Volume
This is a factory-defined value that includes the volume of the optical bench
and associated plumbing inside the Analyzer Control Unit. The default IRGA
volume is 19 cm
3
.
Total Volume
The total system volume, which is computed from the sum of the Chamber
Volume, IRGA Volume, Chamber Offset, and Soil Area.
4. Click on the 8100 menu and choose Outputs. The Output screen appears
(below), where you can configure the raw data values that are sent by the
instrument via the RS-232 port, or via the TCP/IP port, if you are using the
LI-8100A in a wireless network, or with an Ethernet cable. This is primarily
used when capturing raw data values with an external data logging device.
Note that these values are simply sent as a data stream; data are not parsed,
nor is header information included. You can also choose the output
frequency for both RS-232 and/or TCP/IP data.
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