CSAT3B Three-Dimensional Sonic Anemometer
19
CSAT3B before the wind speed is transformed into orthogonal coordinates.
Because of this correction, it is not necessary to apply the speed of sound
correction described by Liu et al., 2001 (see Section
(p. 65)
).
The CSAT3B has several operating modes to suit different applications. The
anemometer can be configured to make a single measurement per data logger
trigger, or it can operate in a self-triggered mode. When self-triggering, the
CSAT3B will make measurements at a high rate, apply an optional user-
selectable bandwidth filter, and provide the latest output upon receiving an
output prompt. An output prompt may come from the data logger, or in the
case of unprompted output mode (such as computer data collection), the output
is prompted by the CSAT3B itself. The default operating mode of the CSAT3B
is to make measurements when triggered by a data logger (SDM or CPI),
which does not apply any low-pass (high-cut) filtering. See Section
(p. 4)
, for a list of all default settings, and see
(p. 48)
, for more information on modes.
6.1 Measurements
Operating Temperature
Standard:
–30 to 50 °C
Wind Accuracy
(–40 to 50 °C, wind speed < 30 m·s
–1
, azimuth angles between ± 170 °C)
Offset Error
u
x
:
± 8 cm·s
–1
max
u
y
:
± 8 cm·s
–1
max
u
z
:
± 4 cm·s
–1
max
Gain Error
Wind Vector ± 5° of horizontal:
± 2% of reading max
Wind Vector ± 10° of horizontal: ± 3% of reading max
Wind Vector ± 20° of horizontal: ± 6% of reading max
Wind Resolution
u
x
:
1.0 mm·s
–1
RMS
u
y
:
1.0 mm·s
–1
RMS
u
z
:
0.5 mm·s
–1
RMS
Wind Full Scale Range:
± 65 m·s
–1
Sonic Temperature Resolution:
± 0.002 °C RMS at 25 °C
Sonic Temperature Reporting Range:
–30 to 50 °C
Measurement Rates
Data Logger Triggered:
1–100 Hz
Unprompted Output (to computer):
10, 20, 50, or 100 Hz
Internal Self-Trigger Rate:
100 Hz
Measurement Delay
Data Logger Triggered (no filter):
1 trigger period (1 scan interval)
Unprompted Output (no filter):
10 ms
Filtered Output (Data Logger Prompted or Unprompted to computer):
795 ms with 5 Hz bandwidth filter
395 ms with 10 Hz bandwidth filter
195 ms with 20 Hz bandwidth filter
155 ms with 25 Hz bandwidth filter
Filter Bandwidths:
5, 10, 20, or 25 Hz
