Campbell Scientific CPEC200 Closed-Path Eddy-Covariance System User Manual
Page 39
CPEC200 Closed-Path Eddy-Covariance System
BATT_DEADBAND:
This variable, along with
BATT_LOWLIMIT, determines when the
CPEC200 will restart after an automatic power shutdown. The CPEC200 will
not restart until the supply voltage
BattVolt reaches at least
BATT_LOWLIMIT + BATT_DEADBAND. The purpose of the deadband
function (the gap between the shutdown voltage and the turn-on voltage) is to
protect the CPEC200 from repeated power cycles when the battery voltage is
very near the limit.
BATT_DEADBAND must be between 0 and 10.0 V. The
default is 1.0 V.
SONIC_AZIMUTH:
The variable
SONIC_AZIMUTH specifies the angle in degrees between true
north and the direction that the sonic anemometer is pointing. For example, if
the sonic anemometer is pointing due east, set
SONIC_AZIMUTH to 90°. If
the sonic anemometer is pointing southwest, enter 225°, and so on.
SONIC_AZIMUTH is used to calculate wnd_dir_compass.
BANDWIDTH:
The CPEC200 program configures the EC155 bandwidth according to system
configuration variable
BANDWIDTH. This variable may be set to any of the
valid settings: 5, 10, 12 (12.5 Hz), 20, or 25. The CPEC200 program will save
the updated setting in the configuration file, configure the EC100 electronics
and update the lag time.
The IRGA data will be invalid for up to one second after changing
the bandwidth as the EC100’s digital filter is reinitialized for the
new bandwidth setting.
The default setting is 20 (20 Hz bandwidth), which preserves all of the high-
frequency fluctuations in the CO
2
and H
2
O measurements. If the raw time
series are processed to give spectra, the user generally should set
BANDWIDTH to 5 (5 Hz). This will filter the IRGA data to avoid aliased
response.
For more information, see the EC155 CO
2
and H
2
O Closed-Path Gas Analyzer
Manual available at
AMB_PRESS_NOMINAL:
This is a backup for when the differential pressure sensor is not used. If
USE_DIFF_PRESS = False, then the value entered here is used for the
ambient pressure in flux calculations. Otherwise the EC100 barometer (basic
or enhanced) is used, and this variable is ignored. See Section 4.1.2.5,
Barometer, for more discussion on the interaction between the EC100
barometer and the differential pressure sensor.
The EC100 always includes the EC100 basic barometer, but it
may be ordered with the optional EC100 enhanced barometer. The
EC100 is configured at the factory to use the enhanced barometer,
if ordered. Normally, the user will not have to change this setting.
If there is a need to check or change this setting, see the EC155
user manual.
NOTE
NOTE
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